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97 APPENDIX D Aggregate Survey Results (All High-Speed WIM Applications)
Survey Results & Analysis for NCHRP Synthesis 38-10 Survey of High Speed WIM System Calibration Practices Saturday, June 2, 2007 Powered by: http://www.websurveyor.com/ 98
99 Executive Summary This report contains a detailed statistical analysis of the results to the survey titled NCHRP Synthesis 38-10 Survey of High Speed WIM System Calibration Practices. The results analysis includes answers from all respondents who took the survey in the 76 day period from Friday, March 16, 2007 to Wednesday, May 30, 2007. 11 completed responses were received to the survey during this time.
Survey Results & Analysis Survey: NCHRP Synthesis 38-10 Survey of High Speed WIM System Calibration Practices Author: T. Papagiannakis and R. Quinley Filter: (In question "13) 2.1 What are the WIM systems for which your unit is primaril..." the respondent selected "Enforcement Screening Only") Responses Received: 11 Is there another unit (department/division/agency) in your State managing high speed WIM systems used for a different purpose (i.e., data collection versus enforcement)? 100
101 Please comment below on whether your unit cooperates with that other unit and how: Not known MT-Enforcement: Motor Carrier Services Division receives enformenent reports from Planning Division for all WIM systems statewide. Planning Division maintains all MDT piezo-based WIM systems, three of which are use for weigh station bypass. MCS Division maintains all Bender-plate WIM systems used for weigh station bypass. CO-Enf: Sites for Enforcement and Data collection have been shared to compare new technologies as well as to fulfill other uses such as traffic monitoring for incident detection and public information WA-Enf: Yes we cooperate together. Some of the CVISN WIM sites give data to the Transportation Data Collection information system. NC-Enf: This unit provides us raw data for interpetation and use in enforcement operations. AZ-Enf: Yes but cooperation has been very limited. They have had little to no interest so far in sharing info with us or from us. ID-Enf: Work in partnership when need arises 2.1 What are the WIM systems for which your unit is primarily responsible used for?
2.2 Which types of WIM systems have been installed by/for your unit? Other Responses: Type III 102
103 2.3 Is auto-calibration typically utilized by your systems during routine data collection? Comment Responses: MT-Enforcement: The bender-plates are not temperature sensitive. AZ-Enf: Also annual calibration by service techs.
If Yes, for which system types? Check all that apply. Other Responses: Comment Responses: 104
105 3.1 Is a post-installation system calibration always performed? Comment Responses:
3.2 Who performs this post-installation calibration? Check all that apply. Other Responses: 106
107 Additional comments: MT-Enforcement: Since the bender-plate systems used by MCS are for high-speed screening in conjuction with AVI (PrePass), in house and vendor staff collect WIM information from 26 type 9, non-liquid, not livestock loads per lane. A scale officers weighs each vehicles axle groups using the static platform scale and records the weights with corresponding WIM record. Using this information, calibration factors are determined and entered into the recorder. Another sample of WIM and corresponding static weight records are collected to verify calibration. This process continues until calibration is achieved and verified. AZ-Enf: IRD installed and maintains all of our sites at this time. 3.3 Is the post installation calibration procedure any different than the routine calibration?
Additional comments: AL-Enf: We have known weight trucks with 2 different axle configurations and run them continuously over the WIM until calibrated WA-Enforcement: We use a known truck, a calibration truck, with known weights and known axle distances during the post installation calibration versus n-trucks from the highway. AZ-Enf: Only to the extent we test and retest it several times at the initial installation calibration acceptance stage. 3.4 Which methods do you use for the evaluation/calibration of high speed WIM systems throughout their lives? Check all that apply. Other Responses: Comment Responses: MD-Enf: PrePass tag comparison method (weights on static scales compared to weights on WIM) MT-Enf: Using weight distribution graphs produced from data collected from each WIM recorder, MCS can observe loaded and unloaded peaks to montor system changes or drifts. We also monitor prepass data for pull ins. CO-Enf: Port Operators track truck weights periodically and call when a pattern of either overweight or under weight vehicles appear AZ-Enf: Annual test required. Also use self calabration and monitering of system on regular basis 108
109 3.5 WIM On-Site Evaluation/Calibration Procedures Using Test Trucks NOTE: The majority of the questions under 3.5 relate to the general provisions of the ASTM Standard E1318-02 and the LTPP WIM System Calibration Protocol. They are intended to determine which parts of these standards your unit may be using. Do you perform on-site evaluation/calibration using test trucks?
110 In the series of questions under 3.5 please describe the procedure you use for the MOST COMMON WIM type in your unit (department/division/agency). What is the most common WIM type in your unit for which test trucks are used for calibration? Other Responses: Comment Responses:
111 3.5.1 Who conducts these on-site evaluation/calibration activities using test trucks? Check all that apply.
112 Additional Comments: AZ-Enf: Use both. IRD is primary contractor. If you are outsourcing WIM calibration, you may want to ask for the contractor's assistance in responding to the following questions. 3.5.2 What is the criterion you use to initiate test-truck WIM calibration? Check all that apply.
113 If routinely scheduled, specify typical interval (months):
114 Additional comments: AZ-Enf: Annual testing with constant on-line monitering by IRD for system review. 3.5.3 Do you have procedures for conducting diagnostic tests to ensure proper operation of the WIM system prior to committing to a complete on-site evaluation and/or calibration?
115 If Yes, how are these diagnostic tests conducted? Check all that apply. Other Responses: Comment Responses:
116 3.5.4 Do you have procedures for inspecting the condition of the WIM sensors?
117 If Yes, on which of the following do you perform a visual inspection? Check all that apply. Other Responses: Comment Responses:
118 3.5.5 When conducting test-truck WIM calibrations, do you consider the pavement smoothness at the WIM site? Comment Responses:
119 In cases where the pavement smoothness is considered which methods are used? Check all that apply. Other Responses: Comment Responses:
120 3.5.6 In conducting WIM calibrations with test trucks, do you consider the structural condition (deflection) of the pavement supporting the WIM sensors? Comment Responses:
121 3.5.7 How are test trucks procured? Check all that apply. Other Responses: Comment Responses:
122 3.5.8 How many test trucks are used by class or type? FHWA Class or Type Number FHWA Class or Type Number FHWA Class or Type Number FHWA Class or Type Number Additional comments (If more than 4 types are used please indicate the type(s) and number (s) here): 9 1 9 1 7 1 Additional comments (If more than 4 types are used please indicate the type(s) and number(s) here):(3.5.8 How many test trucks are used by class or type?) 3.5.9 Do you specify the suspension type of these test trucks? Comment Responses:
123 If Yes, which types are specified? Check all that apply. Other Responses: Comment Responses:
124 3.5.10 What is your test truck loading criteria? Other Responses: WA-Enf: We vary the weight depending on the test performed Comment Responses:
125 3.5.11 Please provide the following details on static weighing in conjunction with WIM calibration using test trucks. Do you require that static scales be certified? Comment Responses:
126 Which types of static scales do you use? Check all that apply. Other Responses:
127 Which static weights are obtained? Check all that apply. Other Responses:
128 How many times is each static weight measured?
129 Additional comments regarding static weight practices: AZ-Enf: We check them twice to insure accuracy 3.5.12 Are the axle spacings for each test truck measured? Comment Responses:
130 3.5.13 Are the test truck speeds measured as they cross the sensors? Comment Responses:
131 3.5.14 How is test truck speed measured? Comment Responses: AZ-Enf: Careful operators of vehicles
132 3.5.15 At what speeds do the test trucks run? Comment Responses:
133 3.5.16 Is there a minimum number of test truck runs required at each speed?
134 If Yes, please specify the minimum number of runs: Number of runs for each speed. 20 3 Additional comments: 3.5.17 Are the test truck drivers given specific instructions as to the desired lane and speed for each run?
135 Additional comments: If Yes, by what means are the instructions given? Check all that apply. Other Responses: AZ-Enf: Verbal instructions Comment Responses:
136 3.5.18 Is the system auto-calibration turned off during test truck runs? Comment Responses: AZ-Enf: We test once without.
137 3.5.19 How is the test truck data being recorded during WIM calibration testing? Other Responses: Comment Responses:
138 If test truck data is manually recorded, what method is used? Other Responses: Comment Responses:
139 3.5.20 When performing on-site calibration using test trucks are the WIM error computations performed on- site? Comment Responses:
140 3.5.21 During on-site calibration using test trucks how are the WIM error computations carried out? Other Responses: Comment Responses:
141 3.5.22 During on-site calibration using test trucks what error formula is used? Other Responses: Comment Responses:
142 3.5.23 For which of the following measurements are WIM errors computed during on-site calibration using test trucks? Check all that apply. Other Responses: Comment Responses:
143 3.5.24 Are test trucks ever run for the sole purpose of determining WIM system accuracy tolerance pass/fail (e.g. new site acceptance, warranty, etc.)? Other Responses: Comment Responses:
144 3.5.25 During on-site calibration using test trucks, what method is used to compute the calibration factors? Other Responses: Comment Responses:
145 3.5.26 During on-site evaluation using test trucks do you compute calibration factors for two or more speed points? Other Responses: Comment Responses:
146 3.5.27 What remedial action is taken for WIM systems that fail to meet accuracy tolerances during test truck testing? Other Responses: AZ-Enf: Repair as needed Comment Responses: AZ-Enf: Problems identifed and resolved. What ever it takes.
147 What is the use of the data being generated by WIM systems that fail to meet accuracy tolerances? Other Responses: Comment Responses: AZ-Enf: Repair as needed.
148 3.6 WIM On-Site Evaluation/Calibration Using Traffic Stream Trucks of Known Weight NOTE: In this section we are referring to on-site evaluation/calibration by sampling trucks from the traffic stream for which you are able to obtain static weights. Do you perform on-site evaluation/calibration using traffic stream trucks of known weights?
149 In the series of questions under 3.6 please describe the procedure you use for the MOST COMMON WIM type in your unit (department/division/agency). What is the most common WIM type in your unit for which traffic stream trucks of known weight are used for calibration? Other Responses:
150 3.6.1 Who conducts these on-site evaluation/calibration activities using traffic stream trucks of known weight? Check all that apply.
151 Additional Comments: LA-Enforcement: WIM Vendor technician(IRD) CO-Enf: Port Operators collect data when time permits. If you are outsourcing WIM calibration, you may want to ask for the contractor's assistance in responding to the following questions. 3.6.2 What is the criterion you use to initiate WIM calibration using traffic stream trucks of known weight? Check all that apply.
152 If routinely scheduled, specify typical interval (months):
153 Additional comments: CO-Enf: A check of the WIM system is done if the Static Scale has been serviced or calibrated. The WIM system is checked if it has been serviced to the static scale. AZ-Enf: POE staff does this when something alerts them there may be a problem. 3.6.3 How do you select the number of traffic stream trucks of known weight to be included in the sample?
154 If a fixed number of trucks are selected, specify the number.
155 If all of the trucks in a given time interval are selected, specify the time interval (in hours).
156 If some of the trucks in a given time interval are selected, specify the number and interval: Number of Trucks Time Interval (in hours) 10 1 10 Additional comments: See 3.6.1 for explanation LA-Enforcement: This is determined by how busy the scale operators, amount of traffic volume, etc. CO-Enf: Site specific due to varying truck volumes. 3 to 5 trucks are checked then an adjustment is made if needed. This continues until consistancy is found in the WIM system. Allowances are made for trucks that are not called in to be weighed or cannot be tracked because the truck pulled over prior to the scale. AZ-Enf: Done until staff is satisfied system is operational and within standards. If not refered to IRD for correction. 3.6.4 What are the criteria used for selecting the type of traffic stream trucks of known weight to include in the sample? Other Responses: Class 9 Comment Responses: MT-Enf: Type 9 vehicles; non-liquid/non-livestock loads. CO-Enf: Trucks under 56,000 gross are discouraged unless vary low volumes exist
157 3.6.5 How is the static weight of these traffic stream trucks obtained? Other Responses: Comment Responses:
158 If using a weight enforcement facility, how is the static weight of the traffic stream trucks recorded? Comment Responses: MT-Enf: Using the PrePass system print-out reports for specific vehicles, the weigh station officer identifies the vehicle and records the axle group weights obtained from the static scale on the PrePass WIM printout. COEnf: If operators are available computer printouts are done on WIM and Static Scale records.
159 3.6.6 Do you measure the axle spacing for these traffic stream trucks? Other Responses: VA-Enf: The first 20 vehicles CO-Enf: Only if a Port Operator request or notices a problem. Comment Responses: Co-Enf: Unless an Port Operator has a specific problem with axle spacing the standard 4.5' between tandoms and 10.9' between split axles is used. I has been found that axle spacings are vary accurate and don't tend to drift.
160 If Yes, how do you measure the axle spacing? Other Responses: Comment Responses:
161 3.6.7 Is the system auto-calibration turned off during traffic stream truck runs? Comment Responses: Co-Enf: Auto-callibration is available but not used.
162 3.6.8 How is the WIM data of the sampled traffic stream trucks of known weight recorded? Other Responses: Comment Responses: MT-Enf: PrePass system allows the printout of WIM information for all vehicles, transpondered or not.
163 3.6.9 Are the on-site calibration using traffic stream trucks of known weight WIM error computations performed on-site? Comment Responses:
164 3.6.10 During on-site calibration using traffic stream trucks of known weight how are the WIM error computations carried out? Other Responses: CO-Enf: A spreadsheet has been used if requested by another agency for comparision Comment Responses:
165 3.6.11 For which of the following measurements are WIM errors computed? Check all that apply. Other Responses: Comment Responses: Co-Enf: Axle Spacing, Speed, and Overall vehicle length are noted only.
166 3.6.12 Are traffic stream trucks of known weight ever sampled for the sole purpose of determining WIM system accuracy tolerance pass/fail (e.g. new site acceptance, warranty, etc.)? Other Responses: Comment Responses:
167 3.6.13 During on-site calibration using traffic stream trucks of known weight, what method is used to compute the calibration factors? Other Responses: Comment Responses: Co-Enf: GVW is used first then Axle loads are compared to fine tune the system
168 3.6.14 During on-site calibration using traffic stream trucks of known weight do you compute calibration factors for two or more speed points? Other Responses: Comment Responses: MT-Enf: The majority of our traffic stream travels within one speed group. Co-Enf: If problems arise Speed is checked and an adjustement is made. To date all calibration factors remain the same.
169 3.6.15 What remedial action is taken for WIM systems that fail to meet accuracy tolerances during traffic stream truck evaluation? Other Responses: AL-Enf: We schedule a re-calibration but continue to use system Comment Responses:
170 What is data from systems that remain in use but fail to meet accuracy tolerances used for? Other Responses: Comment Responses: Each WIM system is evaluated, problem isolated and corrected. As system meet their life-cycle, the department will evaluate and if warranted, deploy new technology to improve operations. AZ-Enf: Site repaired
171 3.7 WIM Calibration Monitoring Using Traffic Stream WIM Data Do you use WIM calibration monitoring using traffic stream WIM data to monitor your WIM systems? Comment Responses:
172 3.7.1 Who conducts WIM calibration monitoring using traffic stream WIM data? Check all that apply.
173 Additional comments: If you are outsourcing WIM calibration, you may want to ask for the contractor's assistance in responding to the following questions. 3.7.2 Typically, how often are your systems' data files downloaded? Other Responses: AZ-Enf: Bi-weekly Comment Responses:
174 3.7.3 How are your systems' data files downloaded? Other Responses: Comment Responses: MT-Enf: For bender--plate sites, manual polling is conducted; for quartz piezo sites, auto-polling proprietary software is used.
175 3.7.4 How often do you perform checks of the WIM data? Other Responses: Comment Responses: MT-Enf: Reviewed when officers at weigh scale location notify HQ of weight differences between the WIM system and Static Scales.
176 3.7.5 How is your WIM data analysis performed? Other Responses: Comment Responses: MT-Enf: Manual review of weigh distribution graphs looking at loaded and unloaded peaks. We also look at the Prepass information. (# of pullins and the reason for pullins)
177 If your data analysis is performed automatically using software, when is it carried out? Comment Responses:
178 3.7.6 In your opinion, do the analyses of your WIM data identify most system operational problems and atypical traffic characteristics? Comment Responses:
179 If Yes, which types of system operational problems and/or atypical traffic characteristics are identified? Check all that apply. Other Responses: speed of vehicles monitored Comment Responses:
180 3.7.7 Which traffic stream vehicle types are utilized for calibration monitoring? Check all that apply. Other Responses: AL-Enf: 2 axle vehicle, tridem 3 axle dump truck, 5 axle lowboy Comment Responses: MT-Enf: Non-liquid/non-livestock loads.
181 3.7.8 Which characteristics are monitored through WIM calibration monitoring using traffic stream WIM data? Check all that apply. Other Responses: AZ-Enf: Axle, Group, Bridge, and gross weights. Comment Responses:
182 3.7.9 If the monitoring of traffic stream characteristics indicates a system is experiencing calibration "drift" what action is taken? Other Responses: Comment Responses: MT-Enf: HQ notifies the Captain in charge of the weigh scale and officers collect the WIM and Static information; mail or fax information to HQ. If needed, factors are computed and entered into the recorder via telephone/modem communications. AZ-Enf: On site if necessary to resolve issues.
183 3.7.10 If calibration factors are adjusted from the office, do you check the effect on the traffic characteristics described in 3.7.8? Those characteristics included: (GVW Average, GVW Average by speed, Steering axle weight average, etc.). To view a complete list click on Previous Page below. Comment Responses: MT-Enf: Yes additional data is collected after each adjustment.
184 3.7.11 Do you keep records of WIM calibration factor adjustments? Comment Responses: AZ-Enf: Contractor keeps info for future use. ID-Enf: The contractor does
185 If Yes, how are records kept? Comment Responses:
186 Part 4: YOUR OPINION 4.1 In your opinion, are your Type I traffic data systems generating data of adequate quality to meet the requirements for the intended purposes?
187 Additional comments: 4.2 In your opinion, are your Type I main line enforcement screening and/or sorting systems effective?
188 Additional comments: 4.3 In your opinion, are your Type II traffic data systems generating data of adequate quality to meet the requirements for the intended purposes?
189 Additional comments: MT-Enforcement: MCS uses bender-plate and piezo quartz screening WIM systems; both are Type 1. 4.4 In your opinion, are your Type II main line enforcement screening and/or sorting systems effective?
190 Additional comments: CO-Enf: The type II systems are for Axle Counts in the adjacent lane only, not used for weight enforcement 4.5 In your opinion, given additional resources for high speed WIM traffic data collection and enforcement, which of the following would your unit consider? Check all that apply.
191 Additional comments: 4.6 In your opinion, what is the main factor hindering proper WIM calibration and how could it be solved? MD-Enforcement: Incompatible WIM systems with static scale systems (ie, one scale vendor's WIM does not work with another scale vendor's static scale). No reliable data available on WIM system deployed elsewhere by dominant scale vendor for our state. VA-Enforcement: Resources and Time. LA-Enforcement: It would be hard to get a more accurate figure without bringing the trucks in off the interstate at a slower and more controlled speed AL-Enf: Roughness of the roadway, Humidity and Temperature CO-Enf: WIM calibration is not a problem. Maintenance of the Sites on Busy highways is difficult. Servicing the systems must be done at night in most areas. Calibration can occur any time and does not disrupt the travelling public. Calibration can be done remotely if the Port Operators provide the data via fax or email. NC-Enf: Manufacturer poor response time for repairs causes unnecessary down time. AZ-Enforcement: Mostly funding to cover testing. ID-Enf: Too many variables concerning the locations, vehicle types can lead to inaccurate calibrations and sorting. 4.7 In your opinion, what are the most urgent WIM technical needs at present and what studies need to be conducted to address them? MD-Enforcement: WIM deployment for Virtual Weigh Stations to monitor known bypass locations. Studies have been conducted to determine which areas/roads to target. The state procurement system is the biggest hindrance to deploy these in a timely fashion. Technical needs - better installation and calibration guidelines from research community based on production grade data, not research data. MT-Enforcement: Montana State University, on behalf of MDT has studied bender-plate vs. conventional piezo systems at same location; findings indicate both systems provided similar accuracy. Recommend similar comparison study of quartz piezo and bender-plate systems in northern tier state. VA-Enforcement: Quality of pavement smoothness. LA-Enforcement: Cars Stealing the trucks signal showing the truck is running scale AL-Enf: Keep up with technology in regards to accuracy and durability CO-Enf: Many WIM systems out live the road surfaces. Many times road surfaces are repaired without thought given to the WIM system and therefore making the WIM system inaffective and sometimes useless. Proper installation combined with proper maintenance of both road surface and WIM system can provide many years of service. Colorado has scales still operational that were installed in 1991 thru 1994. The road surface has been replaced but the system is still operational. NC-Enf: These units are used as a screening device and meets our present need. AZ-Enforcement: Improve technology Please provide any additional comments you may want to share about high speed WIM calibration. CO-Enf: Many times a system is installed but the Road Maintenance department are not informed until they see something in the road. I feel the Road Maintenance department needs to be active in maintaining the system as the accuracy of the WIM system is only as good as the Road Surface leading up to the System. If the Road surface has been damaged or deteriorated then the WIM accuracy does the same. Part 5: INVENTORY OF WIM SYSTEMS This last part of the questionnaire is optional. It is an inventory of WIM systems in your state. Do you want to complete it?
192
193 Dual Use - A Single WIM System Used for Both Traffic Data Collection AND Enforcement Screening Approximate number of Type I WIM Systems Approximate Number of Type I WIM Lanes Sensor Type(s) 1 MD-Enf: Kistler Digital Quartz Sensor 7 13 MT-Enf: Bender Plate and Quartz Piezo 0 0 8 16 LA-Enforcement: IRD SLC, Piezo 14 56 Bending plate 0 0 11 11 WA-Enf: SLC 3 2 NC-Enf: IRD 0 0 6 8 AZ-Enf: Electronic load cell 0 0 Single Use - Traffic Data Collection ONLY Approximate Number of Type I WIM Systems Approximate Number of Type I WIM Lanes Sensor Type(s) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 NC-Enf: IR D 0 0 0 0 0 0 Single Use - Enforcement Screening ONLY Approximate Number of Type I WIM Systems Approximate Number of Type I WIM Lanes Sensor Type(s) 0 0 see dual use above 7 11 MT-Enf: Bender Plate and Quartz Piezo 14 14 VA-Enf: IRD single load cells 0 0 0 0
194 13 15 CO-Enf: Single Load Cells 11 11 WA: Enf: SLC 0 0 0 0 0 0 2 2 ID-Enf: IRD load cell systems Dual Use - A Single WIM System Used for Both Traffic Data Collection AND Enforcement Screening Approximate Number of Type II WIM Systems Approximate Number of Type II WIM Lanes Sensor Type(s) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 AZ-Enf: Peizo 0 0 Single Use - Traffic Data Collection ONLY Approximate Number of Type II WIM Systems Approximate Number of Type II WIM Lanes Sensor Type(s) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Single Use - Enforcement Screening ONLY Approximate Number of Type II WIM Systems Approximate Number of Type II WIM Lanes Sensor Type(s) 0 0 0 0
195 Generated: 6/2/2007 3:58:48 PM 0 0 0 0 0 0 11 11 CO-Enf: Piezo Electric 0 0 0 0 0 6 6 0 0 0 0
Survey Results & Analysis for NCHRP Synthesis 38-10 Survey of High Speed WIM System Calibration Practices Saturday, June 2, 2007 Powered by: http: / /www.websurveyor.com/ 196
197 Executive Summary This report contains a detailed statistical analysis of the results to the survey titled NCHRP Synthesis 38-10 Survey of High Speed WIM System Calibration Practices. The results analysis includes answers from all respondents who took the survey in the 76 day period from Friday, March 16, 2007 to Wednesday, May 30, 2007. 7 completed responses were received to the survey during this time.
Survey Results & Analysis Survey: NCHRP Synthesis 38-10 Survey of High Speed WIM System Calibration Practices Author: T. Papagiannakis and R. Quinley Filter: (In question "13) 2.1 What are the WIM systems for which your unit is primaril..." the respondent selected "Data and Enforcement") Responses Received: 7 Is there another unit (department/division/agency) in your State managing high speed WIM systems used for a different purpose (i.e., data collection versus enforcement)? 198
199 Please comment below on whether your unit cooperates with that other unit and how: OH: In regards to commercial vehicle enforcement, we have two locations on I-75 that are "Pre-Pass" sites. They provide WIM data for prescreening to our enforcement scales. ND: Yes we cooperate with our Highway Patrol. The Planning and Programming Division supplies HP with data/graphs of overloaded trucks by site/hour of day/day of week as well as monthly and yearly summations 2.2 Which types of WIM systems have been installed by/for your unit? Other Responses: CA: We use piezo electric sensors at our WIM sites but only for classification.
200 2.3 Is auto-calibration typically utilized by your systems during routine data collection? Comment Responses:
201 If Yes, for which system types? Check all that apply. Other Responses: Comment Responses:
202 3.1 Is a post-installation system calibration always performed? Comment Responses:
203 3.2 Who performs this post-installation calibration? Check all that apply. Other Responses:
204 Additional comments: 3.3 Is the post installation calibration procedure any different than the routine calibration?
205 Additional comments: 3.4 Which methods do you use for the evaluation/calibration of high speed WIM systems throughout their lives? Check all that apply. Other Responses: ND: monitor front axle, drive tandem and GVW Comment Responses: ND: also monitor temp sensor performance
206 3.5 WIM On-Site Evaluation/Calibration Procedures Using Test Trucks NOTE: The majority of the questions under 3.5 relate to the general provisions of the ASTM Standard E1318-02 and the LTPP WIM System Calibration Protocol. They are intended to determine which parts of these standards your unit may be using. Do you perform on-site evaluation/calibration using test trucks?
207 In the series of questions under 3.5 please describe the procedure you use for the MOST COMMON WIM type in your unit (department/division/agency). What is the most common WIM type in your unit for which test trucks are used for calibration? Other Responses: Comment Responses:
208 3.5.1 Who conducts these on-site evaluation/calibration activities using test trucks? Check all that apply.
209 Additional Comments: If you are outsourcing WIM calibration, you may want to ask for the contractor's assistance in responding to the following questions.3.5.2 What is the criterion you use to initiate test-truck WIM calibration? Check all that apply.
210 If routinely scheduled, specify typical interval (months):
211 Additional comments: MI: Sensor or equipment changes VT: During Summer months on sites with solid installation in the road. 3.5.3 Do you have procedures for conducting diagnostic tests to ensure proper operation of the WIM system prior to committing to a complete on-site evaluation and/or calibration?
212 If Yes, how are these diagnostic tests conducted? Check all that apply. Other Responses: Comment Responses:
213 3.5.4 Do you have procedures for inspecting the condition of the WIM sensors?
214 If Yes, on which of the following do you perform a visual inspection? Check all that apply. Other Responses: NV: Electronic testing for capacitance and impedence MI: Condition of surrounding pavement VT: Oscilliscope testing Comment Responses:
215 3.5.5 When conducting test-truck WIM calibrations, do you consider the pavement smoothness at the WIM site? Comment Responses:
216 In cases where the pavement smoothness is considered which methods are used? Check all that apply. Other Responses: MI: Watching for any truck bounce Comment Responses:
217 3.5.6 In conducting WIM calibrations with test trucks, do you consider the structural condition (deflection) of the pavement supporting the WIM sensors? Comment Responses: CA: Typically not since almost all of our sites are installed in PCC. NV: Visual inspection
218 3.5.7 How are test trucks procured? Check all that apply. Other Responses: Comment Responses:
219 3.5.8 How many test trucks are used by class or type? FHWA Class or Type Number FHWA Class or Type Number FHWA Class or Type Number FHWA Class or Type Number Additional comments (If more than 4 types are used please indicate the type(s) and number (s) here): 9 1 type 9 1 FHWA class 9 1 9 1 9 1 Additional comments (If more than 4 types are used please indicate the type(s) and number(s) here):(3.5.8 How many test trucks are used by class or type?) 3.5.9 Do you specify the suspension type of these test trucks? Comment Responses:
220 If Yes, which types are specified? Check all that apply. Other Responses: Comment Responses:
221 3.5.10 What is your test truck loading criteria? Other Responses: Comment Responses:
222 3.5.11 Please provide the following details on static weighing in conjunction with WIM calibration using test trucks. Do you require that static scales be certified? Comment Responses: ND: All permanent and portable static weigh stations/scales are certified
223 Which types of static scales do you use? Check all that apply. Other Responses: semi-portable platform scales
224 Which static weights are obtained? Check all that apply. Other Responses: and GVW
225 How many times is each static weight measured?
226 Additional comments regarding static weight practices: ND: Once prior to each site calibration and upon refueling of truck MI: We do 2 weights minimum. If there is any discrepancy between the 2 then we will do a 3rd and even a 4th. Some of the time our weights are done by the local Motor Carrier and then compared to the static permanent scales. 3.5.12 Are the axle spacings for each test truck measured? Comment Responses:
227 3.5.13 Are the test truck speeds measured as they cross the sensors? Comment Responses:
228 3.5.14 How is test truck speed measured? Comment Responses: MI: We use a laser speed gun and also by comparing WIM axle spacings to the measured axle spacings VT: WIM readout
229 3.5.15 At what speeds do the test trucks run? Comment Responses: ND: posted speed limit, 5 or 10 mph above and below posted speed limit depending on type of roadway classification MI: We run 3 speeds. The speed limit and 10 MPH above and below.
230 3.5.16 Is there a minimum number of test truck runs required at each speed?
231 If Yes, please specify the minimum number of runs: Number of runs for each speed. 2 20 3 3 Additional comments: MI: 3 runs are done for an initial calibration then 3 runs minimum are done at each speed in the calibration stage and then also in the verification stage. 3.5.17 Are the test truck drivers given specific instructions as to the desired lane and speed for each run?
232 Additional comments: If Yes, by what means are the instructionsgiven? Check all that apply. Other Responses: ND: hand held 2-way radios or cell phone VT: Verbal direction pre-test run Comment Responses:
233 3.5.18 Is the system auto-calibration turned off during test truck runs? Comment Responses:
234 3.5.19 How is the test truck data being recorded during WIM calibration testing? Other Responses: Comment Responses:
235 If test truck data is manually recorded, what method is used? Other Responses: Comment Responses:
236 3.5.20 When performing on-site calibration using test trucks are the WIM error computations performed on- site? Comment Responses: Multiple WIM vendors are used, so the response is for the PEEK ADR units.
237 3.5.21 During on-site calibration using test trucks how are the WIM error computations carried out? Other Responses: Comment Responses:
238 3.5.22 During on-site calibration using test trucks what error formula is used? Other Responses: Comment Responses:
239 3.5.23 For which of the following measurements are WIM errors computed during on-site calibration using test trucks? Check all that apply. Other Responses: speed, wheel load and /or axle load, tandem axle load, axle spacing, overall vehicle length are all monitored and compared to static measurements Comment Responses:
240 3.5.24 Are test trucks ever run for the sole purpose of determining WIM system accuracy tolerance pass/fail (e.g. new site acceptance, warranty, etc.)? Other Responses: LTPP method Comment Responses:
241 3.5.25 During on-site calibration using test trucks, what method is used to compute the calibration factors? Other Responses: VT: We use the same factor for each weight group Comment Responses:
242 3.5.26 During on-site evaluation using test trucks do you compute calibration factors for two or more speed points? Other Responses: Comment Responses:
243 3.5.27 What remedial action is taken for WIM systems that fail to meet accuracy tolerances during test truck testing? Other Responses: NDDOT is early in its WIM program development and we have not had this situation occur to date Comment Responses:
244 What is the use of the data being generated by WIM systems that fail to meet accuracy tolerances? Other Responses: ND: Haven't had to make this determination yet Comment Responses:
245 3.6 WIM On-Site Evaluation/Calibration Using Traffic Stream Trucks of Known Weight NOTE: In this section we are referring to on-site evaluation/calibration by sampling trucks from the traffic stream for which you are able to obtain static weights. Do you perform on-site evaluation/calibration using traffic stream trucks of known weights?
246 In the series of questions under 3.6 please describe the procedure you use for the MOST COMMON WIM type in your unit (department/division/agency). What is the most common WIM type in your unit for which traffic stream trucks of known weight are used for calibration? Other Responses:
247 3.6.1 Who conducts these on-site evaluation/calibration activities using traffic stream trucks of known weight? Check all that apply.
248 Additional Comments: MI: We do this with the help of Motor Carrier. They stop and weight trucks from the traffic stream and we then use those numbers to calibrate. It's rare we use this system any more. If you are outsourcing WIM calibration, you may want to ask for the contractor's assistance in responding to the following questions. 3.6.2 What is the criterion you use to initiate WIM calibration using traffic stream trucks of known weight? Check all that apply.
249 If routinely scheduled, specify typical interval (months):
250 Additional comments: CA: Typically 6 month intervals are optimal, but lack of time and personnel forces some delays. NV: We schedule a verification of calibration factors on an annual basis. As we monitor the performance of the WIM system throughout the year a determination is made if the system has demonstrated calibration drift. If the system has not demonstrated any drift the calibration may be postponed until the following year. This determination is made with available resources in mind, which are always at a premium. MI: This is done more at the wants/needs of Motor Carrier. 3.6.3 How do you select the number of traffic stream trucks of known weight to be included in the sample?
251 If a fixed number of trucks are selected, specify the number.
252 If all of the trucks in a given time interval are selected, specify the time interval (in hours).
253 If some of the trucks in a given time interval are selected, specify the number and interval: Number of Trucks Time Interval (in hours) 20 Additional comments: MI: It varies with what Motor Carrier is able to weigh. Generally it will be at least 20 trucks OR: Initial calibration uses a 50-truck sample. Follow-up calibration (6-month intervals) uses a 20-truck sample 3.6.4 What are the criteria used for selecting the type of traffic stream trucks of known weight to include in the sample? Other Responses: MI: It's usually trucks that are suspected of being near or over weight. Or that might have some other sort of violation. Comment Responses: CA: Typically class 9 trucks. NV: 332000 type 9.
254 3.6.5 How is the static weight of these traffic stream trucks obtained? Other Responses: CA: Most steering axles are of similar weight, we use established estimates as a baseline. Comment Responses:
255 If using a weight enforcement facility, how is the static weight of the traffic stream trucks recorded? Comment Responses:
256 3.6.6 Do you measure the axle spacing for these traffic stream trucks? Other Responses: NV: Only for ten percent of the sample Comment Responses:
257 If Yes, how do you measure the axle spacing? Other Responses: Comment Responses: CA: Axle spacing between the #2 and #3 axle is typically 4.3-4.4 feet
258 3.6.7 Is the system auto-calibration turned off during traffic stream truck runs? Comment Responses:
259 3.6.8 How is the WIM data of the sampled traffic stream trucks of known weight recorded? Other Responses: Comment Responses:
260 3.6.9 Are the on-site calibration using traffic stream trucks of known weight WIM error computations performed on-site? Comment Responses:
261 3.6.10 During on-site calibration using traffic stream trucks of known weight how are the WIM error computations carried out? Other Responses: Comment Responses: CA: Traffic Stream data is calculated in the office.
262 3.6.11 For which of the following measurements are WIM errors computed? Check all that apply. Other Responses: Comment Responses:
263 3.6.12 Are traffic stream trucks of known weight ever sampled for the sole purpose of determining WIM system accuracy tolerance pass/fail (e.g. new site acceptance, warranty, etc.)? Other Responses: Comment Responses:
264 3.6.13 During on-site calibration using traffic stream trucks of known weight, what method is used to compute the calibration factors? Other Responses: Comment Responses:
265 3.6.14 During on-site calibration using traffic stream trucks of known weight do you compute calibration factors for two or more speed points? Other Responses: CA: Traffic stream data is utilized in the office and calibration factors are adjusted from the office. Comment Responses:
266 3.6.15 What remedial action is taken for WIM systems that fail to meet accuracy tolerances during traffic stream truck evaluation? Other Responses: OR: action is taken to correct the problem Comment Responses:
267 What is data from systems that remain in use but fail to meet accuracy tolerances used for? Other Responses: Comment Responses:
268 3.7 WIM Calibration Monitoring Using Traffic Stream WIM Data Do you use WIM calibration monitoring using traffic stream WIM data to monitor your WIM systems? Comment Responses:
269 3.7.1 Who conducts WIM calibration monitoring using traffic stream WIM data? Check all that apply.
270 Additional comments: OH: Generally check the weights of empty class 9 vehicles as compared to 35,000 lbs. If you are outsourcing WIM calibration, you may want to ask for the contractor's assistance in responding to the following questions. 3.7.2 Typically, how often are your systems' data files downloaded? Other Responses: Comment Responses: California utilizes a validation server which downloads data daily from most sites. Other sites are downloaded weekly.
271 3.7.3 How are your systems' data files downloaded? Other Responses: CA: Combinations of auto downloads and manual, the bulk of our sites are downloaded automatically. Comment Responses: MI: Automatically - utilizing in house written auto-polling software
272 3.7.4 How often do you perform checks of the WIM data? Other Responses: Comment Responses:
273 3.7.5 How is your WIM data analysis performed? Other Responses: CA: Some criteria of data analysis is automated, but others require user judgement. Site specific knowledge is needed at some sites. manually, however in-house software has been created to assist in this task by compiling the data into graphs etc MI: Both manualy and automaticaly Comment Responses:
274 If your data analysis is performed automatically using software, when is it carried out? Comment Responses:
275 3.7.6 In your opinion, do the analyses of your WIM data identify most system operational problems and atypical traffic characteristics? Comment Responses:
276 If Yes, which types of system operational problems and/or atypical traffic characteristics are identified? Check all that apply. Other Responses: some of these checks have not been developed yet but are currently being developed in-house Comment Responses:
277 3.7.7 Which traffic stream vehicle types are utilized for calibration monitoring? Check all that apply. Other Responses: MI: We use most vehicles to a certain degree to monitor the basic system but only class 9s for actual calibration Comment Responses:
278 3.7.8 Which characteristics are monitored through WIM calibration monitoring using traffic stream WIM data? Check all that apply. Other Responses: Comment Responses:
279 3.7.9 If the monitoring of traffic stream characteristics indicates a system is experiencing calibration "drift" what action is taken? Other Responses: MI: It's a judgement call. If it's a very minor drift we may adjust it from the office, but it would generally trigger the site for calibration. Comment Responses: OH: Target weights are modified.
280 3.7.10 If calibration factors are adjusted from the office, do you check the effect on the traffic characteristics described in 3.7.8? Those characteristics included: (GVW Average, GVW Average by speed, Steering axle weight average, etc.). To view a complete list click on Previous Page below. Comment Responses:
281 3.7.11 Do you keep records of WIM calibration factor adjustments? Comment Responses: OH: We do neglect to record the changes.
282 If Yes, how are records kept? Comment Responses: MI: We keep both a hard (paper) copy and an electronic copy.
283 Part 4: YOUR OPINION 4.1 In your opinion, are your Type I traffic data systems generating data of adequate quality to meet the requirements for the intended purposes?
284 Additional comments: 4.2 In your opinion, are your Type I main line enforcement screening and/or sorting systems effective?
285 Additional comments: OH: If used in conjunction with enforcement, they are considered a very successful failure. 4.3 In your opinion, are your Type II traffic data systems generating data of adequate quality to meet the requirements for the intended purposes?
286 Additional comments: California does not use Type II systems for weight. No type II systems 4.4 In your opinion, are your Type II main line enforcement screening and/or sorting systems effective?
287 Additional comments: CA: There will be problems with using data from a Type II source, data of poor quality should not be considered for this use. No type II systems MI: We do not use any Type II systems for enforcement or sorting. 4.5 In your opinion, given additional resources for high speed WIM traffic data collection and enforcement, which of the following would your unit consider? Check all that apply.
288 Additional comments: OH: Eliminate WIM data collection. MI: We would like to upgrade many of our type II to type I 4.6 In your opinion, what is the main factor hindering proper WIM calibration and how could it be solved? CA: Funding and lack of personnel is a major issue hindering proper WIM calibration. Field calibrations are very time consuming and expensive, funding increases are needed and qualified staff needs to be available. NV: Acquiring the test vehicles which are very expensive. The only way to solve the problem is to identify additional funding. ND: Manpower/time constraints/funding. NDDOT will try to keep calibration procedure in-house MI: VERY time and resource consuming. VT: Weather and pavement quality related issues. OR: N/A 4.7 In your opinion, what are the most urgent WIM technical needs at present and what studies need to be conducted to address them? CA: Controller stability and sensor life. WIM controllers are a very expensive item and the reliability of these units is somewhat variable. Concerns regarding their housing and components comes into question. Housing elements are subject to extreme temperatures and insects/rodents. Secure mil-spec housing designs should be incorporated. WIM sensors are prone to failure, partly due to the large volume of trucks. Knowing these forces, more metallugy studies may be needed to done to evaluate the optimum materials to be used. Sensor strain gauges in bending plates may need refinement in the areas of adhesion and failure. NV: I would say this study is the most urgent techical need. Best calibration practices need to be identified and standardized. ND: Obtaining more consistent, well calibrated high speed dynamic weights for Highway Patrol useage and design criteria uses. More technical manuals made available by the vendor MI: Find an accurate sensor that is not so costly. VT: Cost effective sensors that are consistent and easier to install. OR: N/A Please provide any additional comments you may want to share about high speed WIM calibration. OH: Only do the absolute minimum WIM data collection. OR: N/A Part 5: INVENTORY OF WIM SYSTEMS This last part of the questionnaire is optional. It is an inventory of WIM systems in your state. Do you want to complete it?
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290 Dual Use - A Single WIM System Used for Both Traffic Data Collection AND Enforcement Screening Approximate number of Type I WIM Systems Approximate Number of Type I WIM Lanes Sensor Type(s) 6 16 CA: Bending Plates 1 4 NV: Quartz Kistler and bending plate 12 0 ND: Kistler Quartz Piezo 20 80 MI: Quartz Bending Plate 0 0 22 24 OR: Single Load Cell Single Use - Traffic Data Collection ONLY Approximate Number of Type I WIM Systems Approximate Number of Type I WIM Lanes Sensor Type(s) 101 412 CA: Bending Plates on 100 and 1 Kistler 5 20 NV: Quartz Kistler and bending plate 0 0 13 52 MI: Quartz Bending Plate 0 0 0 0 Single Use - Enforcement Screening ONLY Approximate Number of Type I WIM Systems Approximate Number of Type I WIM Lanes Sensor Type(s) 28 60 CA: Bending Plates 0 0 0 0 0 0 0 0 0 0 Dual Use - A Single WIM System Used for Both Traffic Data Collection AND Enforcement Screening Approximate Number of Type II WIM Systems Approximate Number of Type II WIM Lanes Sensor Type(s) 0 0 0 0 0 0 24 96 MI: Piezo 17 46 VT: Class 1 RoadTrax
291 Generated: 6/2/2007 4:02:16 PM BL 0 0 Single Use - Traffic Data Collection ONLY Approximate Number of Type II WIM Systems Approximate Number of Type II WIM Lanes Sensor Type(s) 0 0 0 0 0 0 24 96 MI: Piezo 0 0 0 0 Single Use - Enforcement Screening ONLY Approximate Number of Type II WIM Systems Approximate Number of Type II WIM Lanes Sensor Type(s) 0 0 0 0 0 0 0 0 0 0 0 0
292 Survey Results & Analysis for NCHRP Synthesis 38-10 Survey of High Speed WIM System Calibration Practices Saturday, June 2, 2007 Powered by: http: / /www.websurveyor.com/
293 Executive Summary This report contains a detailed statistical analysis of the results to the survey titled NCHRP Synthesis 38-10 Survey of High Speed WIM System Calibration Practices. The results analysis includes answers from all respondents who took the survey in the 76 day period from Friday, March 16, 2007 to Wednesday, May 30, 2007. 34 completed responses were received to the survey during this time.
294 Survey Results & Analysis Survey: NCHRP Synthesis 38-10 Survey of High Speed WIM System Calibration Practices Author: T. Papagiannakis and R. Quinley Filter: (In question "13) 2.1 What are the WIM systems for which your unit is primaril..." the respondent selected "Data") Responses Received: 34 Is there another unit (department/division/agency) in your State managing high speed WIM systems used for a different purpose (i.e., data collection versus enforcement)?
295 Please comment below on whether your unit cooperates with that other unit and how: FL: Motor Carrier Compliance (our enforcement office) also has installed a number of WIM systems at their fixed scale locations. They use their WIM systems for pre-pass and screening. Motor Carrier puts their screening WIM data into an FTP site, and I download that data routinely. I consider the Motor Carrier WIM data to be biased, because overweight trucks can easily avoid the fixed weigh stations, but it has been interesting to compare their data to my own. CT-R: We cooperate with these units as needed and as requested. We are responsible for LTPP data collection and research studies involving evaluation of WIM technologies. MT-Traffic: My unit (Traffic Data Collection) installs, calibrates and maintains the Kistler sensor based WIM systems used for some of Motor Carrier Services Pre-Pass systems. In addition, we collect data from bender plate WIM systems that are calibrated and maintained by Motor Carrier Services. These bender plate WIM systems are used with some of Motor Carrier Systems' Pre-Pass sites. We also provide portable WIM data to Motor Carrier Services for enforcement purposes. NE-Traffic WIM test vs static scales NM-Traffic: Port of Entries have some high-speed WIMS WA-Traffic: Our repair crew occasionally does work for the CVISN section. NJ: We are currently at the planning stage of upgrading some of our WIM systems to be used for "Virtual Weigh Stations" . None of the sites have been upgraded to Virtual Weigh Station yet, so currently no WIM system is being used for enforcement. VA-Traffic: The two agencies cooperate as follows: The DOT, which is responsible for traffic data collection, allows the DMV to wirelessly connect to some of their WIMs during mobile enforcement operations. The DMV, which is responsible for enforcement, shares the traffic data collected at their WIMs with the DOT. NY: Passenger & Freight Safety Division is responsible for a pilot project that includes the installation of commericial vehicle electronic screening equipment. Included in this project is three types of WIM equipment; piezo electric (NYS standard), quartz piezos and load cells. The three types of WIM equipment will be evaluated as part of this project with additional commercial vehicle screening sites installed in subsequent years. The three types of WIM equipment will be installed in the east bound driving lane, however the remaining three lanes include our standard piezo electric, so this will be a fully functioning WIM site for NYSDOT. Our relationship with Passenger & Freight Safety includes reviewing all contract plans, site evaluation/inspection, maintenance of the site after the warranty period expires, and traffic data collection and analysis. MS: Corespondence between planning and law enforcement occurs to discuss quality of WIM data and potential WIM sites in the future. New software is being purchased, Transmetric in which more coordination will occur. Law enforcement is primarily concerned with heavy trucks and axle spacings. MA: tentative plans for future cooperation AZ-LTPP: Internal consultations. AL-Traffic: The data collected from the enforcement systems are stored on our file server. We generate 3-card and C-cards from these files for our use. UT: I borrow and archive their data CT-Traffic: We use research for portable calibration. They rent trucks for their LTTP calibration we take part in it. Yes AK: We provide truck weight data to Division of MSCVE Commerical Enforcement for secondary enforcement. MSCVE is going to deploy CVISN using the 3 of the planning WIM sites in the near future. KS: We send them data summaries annually ID-Traffic: Yes, we work together informally exchanging information on equipment and results. NH: No Cooperation 2.1 What are the WIM systems for which your unit is primarily responsible used for?
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297 2.2 Which types of WIM systems have been installed by/for your unit? Other Responses: MT-Traffic: Portable WIM, which is set up in a Type I configuration, but only weighs the right-hand side of the vehicle. MS: We have 15 operational Type II BL sites and 1 operational Type I Bending Plate Site. UT: Type III IN-Traffic: Single Load Cell, Piezo, DOS O/S ID-Traffic: IRD and ECM permanent systems - channelized and BL sensors.
298 2.3 Is auto-calibration typically utilized by your systems during routine data collection? Comment Responses: MT-Traffic: Kistler-based Type I systems do not use auto-calibration. MS: Our system has the capability of auto-calibrating, but this function is turned off. UT: I do it manually weekly when able TX: Thermocoax Sensors Only Auto calibration is the ONLY calibration done.
299 If Yes, for which system types? Check all that apply. Other Responses: CT-R: Earlier work on evaluating WIM used systems that needed autocalibration to function. For that reason we have installed quartz sensors at LTPP sites and do not use autocalibration. MT-Traffic: Portable WIM uses auto-calibration. IN-Traffic: Only for piezo sensors ID-Traffic: Both IRD and ECM permanent systems use auto calibration. Comment Responses: MT-Traffic: Portable WIM data is collected only for Motor Carrier Sevices as an aid to enforcement.
300 3.1 Is a post-installation system calibration always performed? Comment Responses: MT-Traffic: Post-installation calibration is performed on the Type II systems after they have seen at least 2 weeks of traffic with the default calibration factors in place. NJ: 3 stage system calibration AL-Traffic: We let the system autocal and make adjustments while on site. Then check the weights from the office for the next week or so. ID-Traffic: Based on first axle weights from traffic stream -- NOT vehicle of known weight.
301 3.2 Who performs this post-installation calibration? Check all that apply. Other Responses: CT-R: We traditionally have the WIM vendor conduct the initial calibration, but have an in-house staff person present for all aspects of the process.
302 Additional comments: NJ: Vendor performs hardware testing and initial calibration. Then, two weeks of data is then analyzed in-house before final acceptance. AK: IRD employs a subcontract to complete calibrate (2X year spring and fall) and maintenance in AK. The sub was previously employed by IRD. 3.3 Is the post installation calibration procedure any different than the routine calibration?
303 Additional comments: WA-Traffic: Using traffic stream instead of known weigh truck. AK: Only a single class type is used...type9. TX: Calibration of Speed and Axle Spacing, Vehicle Length, and Front Axle 3.4 Which methods do you use for the evaluation/calibration of high speed WIM systems throughout their lives? Check all that apply. Other Responses: CT-R: Have used all three and combinations of. Primary basis: multiple test trucks. MA: Only using auto-calibration feature Peek Traffic ADR 2000. AL-Traffic: We perodically check the steering axle weights of loaded class nine trucks UT: Post collection calibration TN: Counters self-calibrate with known number of trucks. IL: IL none NH: We only calibrate with trucks when new sensors are installed. Comment Responses:
304 MT-Traffic: Known traffic stream evaluation is only conducted if the site is located near a scale house (such as a Pre-Pass WIM site). Currently, this is only on Type I systems (Kistler sensors) NJ: Calibartion with test truck once every 2 years and adjusted as needed based on WIM Calibration Monitoring of 5-axle semi trailers. AL-Traffic: Ideally the systems would be checked each year on site using a class 9 of known weight. But we currently lack the manpower to do this. In NH we do not run calibration trucks on a regular basis over the lifetime of the sensors. Auto calibration is the only calibration done.
305 3.5 WIM On-Site Evaluation/Calibration Procedures Using Test Trucks NOTE: The majority of the questions under 3.5 relate to the general provisions of the ASTM Standard E1318-02 and the LTPP WIM System Calibration Protocol. They are intended to determine which parts of these standards your unit may be using. Do you perform on-site evaluation/calibration using test trucks?
306 In the series of questions under 3.5 please describe the procedure you use for the MOST COMMON WIM type in your unit (department/division/agency). What is the most common WIM type in your unit for which test trucks are used for calibration? Other Responses: IN-Traffic: Piezo, then SLC Comment Responses: NJ: We only used loaded 5-Axle Single Trailer Trucks for calibration We have one type I bending plate site in which a test truck is utilized as well. TX: We are trying to get away from Thermocoax sensors
307 3.5.1 Who conducts these on-site evaluation/calibration activities using test trucks? Check all that apply.
308 Additional Comments: NJ: The initial calibration is done by contractor/vendor included in the installation and then by in-house staff every 2 years. NY: Staff include those from Traffic Monitoring Section, NYSDOT Residency closest to the WIM site, and NYS Troopers to statically weigh the test vehicle. AK: Contract with WIM vendor for maintenance and calibration. Will try to meet with contactor. If you are outsourcing WIM calibration, you may want to ask for the contractor's assistance in responding to the following questions. 3.5.2 What is the criterion you use to initiate test-truck WIM calibration? Check all that apply.
309 If routinely scheduled, specify typicalinterval (months):
310 Additional comments: FL: My WIM systems are calibrated whenever they are first installed; whenever any major component is replaced; and whenever the data indicates a drift in GVW distribution; the average steering axle weight of a large sample (more than 100) of class 9 trucks falls outside the range of 9000 - 12000 pounds; or the average drive axle spacing falls outside a 4.1 - 4.3 foot range. And two of my LTPP WIM sites are calibrated annually by FHWA as part of the pooled fund project. MT-Traffic: We typically calibrate each site twice per year, once in the spring and once in the fall. Calibration in Montana is somewhat weather dependent. Data from each site is monitored and reviewed on a weekly basis for error trends or changes in traffic stream makeup (QA/QC checks) using reports generated by our traffic data processing software. Monthly calibration graphs are generated and evaulated for drift and truck weight characteristics as well. Additional calibration (outside of the scheduled calibration) may be performed on a system that has had sensorsor electronics replaced, or exhibits problems that requires the test truck for evaluation. AR-Traffic: AHTD plans to begin routine calibration (bi-annual) of WIMs in late summer/fall of 2007. NJ: We maintained over 60 WIM sites and tried to calibrate each site as often as as possible, when electronics are replaced or there is calibration drift. VA-Traffic: This typically has been about twice per year NY: All WIM sites are calibrated on an annual basis, except for sites such as I-495 in Queens that has traffic volumes that are too high to allow for a safe manual calibration of the system. AK: 6 months is the ideal but not less than 5 months or greater than 7. KS: scheduled annually, not always done TX: 12 months for Bending plate and 6 months for coax 3.5.3 Do you have procedures for conducting diagnostic tests to ensure proper operation of the WIM system prior to committing to a complete on-site evaluation and/or calibration?
311
312 If Yes, how are these diagnostic tests conducted? Check all that apply. Other Responses: CT-R: Check sensor output, check reasonableness of data. PA: Vendor calls site to diagnose the counter RI: real time viewing of traffic AK: scope traces are evaluated, Comment Respon ses: MT-Traffic: Sites to be calibrated need to be running "normally" a minimum of 2 weeks prior to calibration, or they get scheduled at a later time. PA: Data can be analyzed from the office AK:...an "as recieved" 5 pass test preceeds baseline tuning followed by the optimization tuning before the final 10 pass test.
313 3.5.4 Do you have procedures for inspecting the condition of the WIM sensors?
314 If Yes, on which of the following do you perform a visual inspection? Check all that apply. Other Responses: CT-R: meter at cabinet for sensor output NJ: Sensor connectors to the electronics WY-Traffic: Oscilloscope Measurements OK: Digitaly Measure Sensor's outputs Comment Responses: MT-Traf: Other checks are performed as well including inspection of pull boxes, conduit, and wiring along with the condition of the cabinet and solar panel (if applicable). We also inspect the roadway for visual signs of decay or topography changes. NJ: Visual inspection of loops and sensors is performed every site visit AK: twice annual mounting hardware checks are conducted.
315 3.5.5 When conducting test-truck WIM calibrations, do you consider the pavement smoothness at the WIM site? Comment Responses: MT-Traffic: We make note of any visual damage and get a verbal report from the test truck driver as well. AK: 330' concrete pads, that were correctly profiled upon installed are used at all sites...the long studded tire season here does cause degredation i.e. wheel rutting, common to asphalt elsewhere requires the addition of grout builup to maintain KS: Most type-II were placed to fit SHRP sites TX: I consider this critical
316 In cases where the pavement smoothness is considered which methods are used? Check all that apply. Other Responses: MT-Traffic: We watch not only our test truck, but other types of trucks as well. OK: Calibrations factors are unstable Comment Responses: VA-Traffic: We use the LTPP WIM Smoothness Software to get the LRI and SRI
317 3.5.6 In conducting WIM calibrations with test trucks, do you consider the structural condition (deflection) of the pavement supporting the WIM sensors? Comment Responses: CT-R: So not have FWD, consider deflection when selecting site based on pavement structure. MT-Traffic: We capture sensor wave form output using the test truck on a storage oscilloscope. Wave form analysis, along with road construction data, allow us to assess structural condition. We mainly look for signal noise coming from the WIM sensor that may be caused by a bad supporting structure for the WIM sensors. NY: Visual MS: Our WIM sites are chosen in locations where the pavement conditions are the best. If there is rutting in the pavement it can cause a truck to bounce and give inaccurate readings. If it is consistantly a problem the WIM site will be moved. PA: Stored in the WIM system AK: Portland cement pads provide consistency at all temperatures. GA: Asphalt or Concrete TX: Research Project
318 3.5.7 How are test trucks procured? Check all that apply. Other Responses: CT-R: Post-installation sometimes aquired by vendor, all other calibrations, DOT rents with operator. Negotiates who supplies load. NJ: Using trucks owned by other state agency. RI: Installation contractor provides test truck as specified in the contract Comment Responses: NJ: Calibration can only be done during Saturdays when trucks are not in use. NJDOT pays only the driver overtime and gas used. NY: Trucks are provided by the Resident Engineer at the NYSDOT Residency closest to the WIM site.
319 3.5.8 How many test trucks are used by class or type? FHWA Class or Type Number FHWA Class or Type Number FHWA Class or Type Number FHWA Class or Type Number Additional comments ( If more than 4 types are used please indicate the type (s) and number(s) here): 9 1 9 2 CT-R: Over the years we have used many different configurations. Most recently we have used on box (5 axle) moving van, loaded with steel tiles. And one dump truck eveny loaded with tiles. We found it critical to the calibration to rent at least one of the same vehicles (not type- exact vehicle) from the previous calibration to baseline if the change is from the test truck or individual vehicles. 9 1 9 1 Class 9 1 Class 9 1 10 1 Class 9 1 NY: Class 9 Lowboy with a dump truck filled with half a load on it. 9 1 Scheme F Type 9 1 vc 9 1 Class 9 1 9 2 9 1 9 1 9 1 9 1 type 9 1 9 1 6 1 9 1 Type 9 1 Type 5 1 FHWA Class or Type (3.5.8 How many test trucks are used by class or type?) FHWA Class or Type 9 9
320 9 9 Class 9 Class 9 10 Class 9 9 Scheme F Type 9 vc 9 Class 9 9 9 9 9 9 type 9 9 6 9 Type 9 Number (3.5.8 How many test trucks are used by class or type?)
321
322 FHWA Class or Type (3.5.8 How many test trucks are used by class or type?) FHWA Class or Type Type 5 Number (3.5.8 How many test trucks are used by class or type?)
323 Additional comments (If more than 4 types are used please indicate the type(s) and number(s) here): (3.5.8 How many test trucks are used by class or type?) CT-R: Over the years we have used many different configurations. Most recently we have used on box (5 axle) moving van, loaded with steel tiles. And one dump truck eveny loaded with tiles. We found it critical to the calibration to rent at least one of the same vehicles (not type- exact vehicle) from the previous calibration to baseline if the change is fromthe test truck or individual vehicles. NY: Class 9 Lowboy with a dump truck filled with half a load on it. 3.5.9 Do you specify the suspension type of these test trucks? Comment Responses: MD-Traffic: Don't specify but it always an air suspension AK: leaf springs are prevalent to the general population
324 If Yes, which types are specified? Check all that apply. Other Responses: CT-R: Often what you specifiy and what arrives at the site differ. Some vehicles are fully air-ride others say they are airride but it is on the trailer only. So you need to further specify. Comment Responses: NJ: Air suspension is preferred but not always used. MS: Air ride trucks are used to help minimize the bounce that might be encountered.
325 3.5.10 What is your test truck loading criteria? Other Responses: CT-R: Fully loaded best they can. Often this is in the 60-70,000 lbs range. They tend to not load too full to save gas if they are rented on a contract hourly rate. The fuller load provides a stable vehicle. Have tried different loadings for research VA-Traffic: Lowboy trailer with heavy piece of construction equipment, typically a loader or grader. GVW has been 63 to 75 KIPs. NY: Loaded to approximately 80,000 lbs. WV: 70,000 to 80,000 Comment Responses: NJ: Axles configured with no bridge violation
326 3.5.11 Please provide the following details on static weighing in conjunction with WIM calibration using test trucks. Do you require that static scales be certified? Comment Responses: MT-Traffic: Certification is the responsibility of Motor Carrier Services WV Do not use static scales MS: Our truck is weighed at MDOT truck scale facilities or at certified truck stops. KS: Grain Elevator scales are common
327 Which types of static scales do you use? Check all that apply. Other Responses: CT-R: Full-vehicle. This is important- some fixed, but the vehicle is on grade. Also require off brake.
328 Which static weights are obtained? Check all that apply. Other Responses: FL: Also GVWT CT-R: Roll on scale, therefore try to get by axle, but is more practical by axle group. NJ: Front axle and GVW only NY: Individual wheel/wheel sets are obtained and axle weights are calculated for each axle.
329 How many times is each static weight measured?
330 Additional comments regarding static weight practices: MT-Traffic: Static weight is taken at the nearest scale house as often as is possible. In Montana, there are many more WIM systems than there are static scales sites, and many of those static scale sites are not manned 24/7. We weigh the truck as often as possible over the six week period in the spring, and the six week period in the fall, that comprises our calibration time. VA-Traffic: This is done by a mobile enforcement crew using their established procedures. All wheels/wheel sets are weighed simultaneously on level ground with brakes locked. This uses 12 portable scales for a 6 axle tractor trailer. MS: Our test truck is also weighed at MDOT truck scales when calibration sites are in close proximities. AK: the second weight check will exclude the last weigh pad. OK: Once before each WIM site is calibrated. 3.5.12 Are the axle spacings for each test truck measured? Comment Responses: NY: Distances between the test vehicles axles are measured in feet MS: Axle spacing is looked at on a daily basis for the WIM sites as a QA/QC. If any spacings are out of tolerance, it is looked at immediately. However, at the time it is not a requirement during calibration with test trucks.
331 3.5.13 Are the test truck speeds measured as they cross the sensors? Comment Responses: MT-Traffic: We record WIM speed on every pass. It is verifed against the axle spacing.
332 3.5.14 How is test truck speed measured? Comment Responses: CT-R: All are checked during the post-installation, after that WIM speeds are compared to truck speedometers, lengths are checked and if something is really off, usually there is a breakdown. NJ: Speed is also check using radar speed gun. NY: Speed is recorded from the counter display on a laptop computer that is connected to the site through our TRAFMAN software. WV: Speed of test truck GA: Speedometer in test truck
333 3.5.15 At what speeds do the test trucks run? Comment Responses: CT-R: At other location, 2 lane rural- uses posted speedlimit (35) MT-Traffic: Speed limits in Montana are different for trucks than for other vehicles. We run as close to the posted speeds as we can. Some WIM sites are located in areas where the truck cannot reach the posted speed limit (due to road topography). WV: 50-55 for lower speed roads and 65-70 for high speed roads KS: Prevailing speed, or as fast as able. Avoid acceleration over scale
334 3.5.16 Is there a minimum number of test truck runs required at each speed?
335 If Yes, please specify the minimum number of runs: Number of runs for each speed. 3 5 6 10 5 10 10 7 3 20 10 10 10 8 10 2 Number of runs for each speed. (If Yes, please specify the minimum number of runs:)
336
337 Additional comments: MT-Traffic: One pass is made in each lane to take raw sensor output data on the oscilloscope. Five passes are made in each lane to record the WIM data that will be used to determine calibration factors for the system. NJ: 5 runs or or more until enough consistent weight is obtained. MS: The seven runs have to be consecutive and withing tolerance. AK: 10 passes after optimum cal factor is identified. KS: I would stop with 4 if the weights are within the readout precision. 3.5.17 Are the test truck drivers given specific instructions as to the desired lane and speed for each run?
338 Additional comments: MT-Traffic: The driver and the site tech talk ahead of each calibration to determine the lane order. The speed is based on the truck speed limit for that roadway, if possible. AK: Consistant speed across the array (whatever speed hey are carrying) must be maintained. If Yes, by what means are the instructions given? Check all that apply. Other Responses: CT-R: State provided radios- asked to alter lanes and speeds, but specific instructions are given depending upon outcome and needs at time of calibration. NY: Meeting with driver and directions given prior to testing RI: visual signals WY-Traffic: Precalibration Meeting TX: hand held radios Comment Responses:
339 3.5.18 Is the system auto-calibration turned off during test truck runs? Comment Responses: MT-Traffic: The Kistler based systems do not have auto-calibration enabled at all. NJ: Off only during initial calibration. KS: test truck is not an auto-calibrate class
340 3.5.19 How is the test truck data being recorded during WIM calibration testing? Other Responses: CT-R: both manual and computer output on dotmatrix in field. RI: Unknown- you may want to check with IRD to find out what their proceedure is Comment Responses: NJ: Each sensor is calibrated independently
341 If test truck data is manually recorded, what method is used? Other Responses: write in book, if time input into spreadsheet in field, otherwise in office post-calibration. AK: click and paste through wireless connection through to laptop. TX: Log File matching manual recordings Comment Responses: MT-Traffic: We use a form that is designed specifically for WIM calibration. We also capture the electronic data that is shown on our laptop screens in a separate file from any of the other WIM files. RI: infomation entered into an Excel Spreadsheet
342 3.5.20 When performing on-site calibration using test trucks are the WIM error computations performed on- site? Comment Responses: CT-R: We always try to, unless problems encountered when time does not permit and it is known that additional runs will be conducted next day. MT-Traffic: On-site calculations are performed on Kistler bases systems only. VA-Traffic: This is usually done the next day in the office Unknown- Check with IRD AK: Required to produce an optimum cal factor.
343 3.5.21 During on-site calibration using test trucks how are the WIM error computations carried out? Other Responses: GA: Using a spreadsheet or other analysis program supplied by contractor Comment Responses: MT-Traffic: Manual computation is done on Type I Kistler systems only. Spreadsheet analysis is done in the office for all other sites.
344 3.5.22 During on-site calibration using test trucks what error formula is used? Other Responses: PA: WIM measurement vs weigh sheet measurement Comment Responses: MT-Traffic: This is used for manual calibration only. Many other factors are considered when using spreadsheet analysis.
345 3.5.23 For which of the following measurements are WIM errors computed during on-site calibration using test trucks? Check all that apply. Other Responses: Primarily Gross Vehicle Weight, check if other items look okay,-if time allows other items are calculated. If not adjustable, time not spent on-site. KS: Classification - analog for spacing error Comment Responses: MT-Traffic: Speed and length are checked during the calibration. Gross weight errors are looked at separately during the office analysis process.
346 3.5.24 Are test trucks ever run for the sole purpose of determining WIM system accuracy tolerance pass/fail (e.g. new site acceptance, warranty, etc.)? Other Responses: Comment Responses: MT-Traffic: In most cases we do combine calibration with accurracy validation, but not always.
347 3.5.25 During on-site calibration using test trucks, what method is used to compute the calibration factors? Other Responses: CT-R: Or close to- using what seems most reasonable based on the truck consistency- zero is sometimes too precise for these measurements. MT-Traffic: The factors are calculated using an in-house designed spreadsheet that incorporates many parameters to determine calibration factors. Comment Responses: MT-Traffic: The prime factor is based on the mean error of GVW, but many other parameters influence the final factor(s).
348 3.5.26 During on-site evaluation using test trucks do you compute calibration factors for two or more speed points? Other Responses: CT-R: Tests show that weights are not dependent on speed- may have capability of factors for multiple speeds, but test results did not show needed. Comment Responses: MT-Traffic: We run at posted truck speed limits when possible. Montana posts lower speeds for trucks than for other vehicles on all roads. RI: Unknown - check with IRD
349 3.5.27 What remedial action is taken for WIM systems that fail to meet accuracy tolerances during test truck testing? Other Responses: CT-R: Try to determine cause of failure, see if vehicle dependent or if any remedies are feasible. MT-An immediate site evaluation is conducted. The site is re-scheduled for calibration as soon as the problem is fixed. PA: Electrical tests/site conditions evaluated Comment Responses: Sites are evaluated structurally, and using data analysis on traffic stream data. If shown to be out of spec, and there is no way to correct the problem structurally, the site may be shut down. WA-Traffic: site may be downgraded to a classification only format NJ: Site is downgraded to Classification/Counting station. RI: Depends on what is causing the problem If the problem is sensors, they will be replaced.
350 What is the use of the data being generated by WIM systems that fail to meet accuracy tolerances? Other Responses: CT-R: Viewed with caution, depending upon site and issues. Different if did not meet inital accuracy versus changed over time. Only one lane installed, where data weight data extremely suspect. Still used for count/ trucks vs small vehicle for class. NJ: speed monitoring PA: Site is repaired Comment Responses: Count class data is monitored for consistency and historical accuracy. If error rates become too high, the site is shut down.
351 3.6 WIM On-Site Evaluation/Calibration Using Traffic Stream Trucks of Known Weight NOTE: In this section we are referring to on-site evaluation/calibration by sampling trucks from the traffic stream for which you are able to obtain static weights. Do you perform on-site evaluation/calibration using traffic stream trucks of known weights?
352 In the series of questions under 3.6 please describe the procedure you use for the MOST COMMON WIM type in your unit (department/division/agency). What is the most common WIM type in your unit for which traffic stream trucks of known weight are used for calibration? Other Responses: We currently run all but two Type I sites as the WIM part of Pre-Pass systems. We only use traffic stream data to confirm our test truck calibration.
353 3.6.1 Who conducts these on-site evaluation/calibration activities using traffic stream trucks of known weight? Check all that apply.
354 Additional Comments: If you are outsourcing WIM calibration, you may want to ask for the contractor's assistance in responding to the following questions. 3.6.2 What is the criterion you use to initiate WIM calibration using traffic stream trucks of known weight? Check all that apply.
355 If routinely scheduled, specify typical interval (months):
356 Additional comments: MT-Traffic: We only use traffic stream trucks to adjust calibration when we have evidence of drift, or when we want to confirm our test truck calibration. This is only conducted at the Pre-Pass WIM sites, as they are the only ones close enough to a static scale to use the traffic stream method. All of the Pre-Pass sites are Type I. VA-Traffic: This is usually done about every 6 months. CT-Traffic: We talk to different motor cariers about the loads that they carry. TX: 12 months bending plate 6 months coax 3.6.3 How do you select the number of traffic stream trucks of known weight to be included in the sample?
357 If a fixed number of trucks are selected, specify the number.
358 If all of the trucks in a given time interval are selected, specify the time interval (in hours).
359 If some of the trucks in a given time interval are selected, specify the number and interval: Number of Trucks Time Interval (in hours) 50 1 10 1 Additional comments: MT-Traffic: The number of trucks used depends on the volume of trucks at the site. High volume sites would not use every truck. Low volume sites will yield a small number of trucks, even after 4 hours. We may take more than 4 hours if the truck volume is judged to be too low. Agencies cal truck 3.6.4 What are the criteria used for selecting the type of traffic stream trucks of known weight to include in the sample? Other Responses: UT: Slow <55 Medium Fast >70
360 CT-Traffic: Class 9"s Comment Responses: NM-Traffic: empty flatbed class 9 Classes 9 and 10 Classes 6 and 9 TX: We look at type 9, typical truck class
361 3.6.5 How is the static weight of these traffic stream trucks obtained? Other Responses: NM-Traffic: front axle weight CT-Traffic: Talked with different companies about their loads Comment Responses:
362 If using a weight enforcement facility, how is the static weight of the traffic stream trucks recorded? Comment Responses: Data is relayed via radio or phone between the scale house and the WIM site.
363 3.6.6 Do you measure the axle spacing for these traffic stream trucks? Other Responses: Comment Responses: TX: agency cal truck
364 If Yes, how do you measure the axle spacing? Other Responses: Comment Responses:
365 3.6.7 Is the system auto-calibration turned off during traffic stream truck runs? Comment Responses: This type of testing is performed only on Kistler based systems at this time. We do not run auto-calibration with Kistler systems.
366 3.6.8 How is the WIM data of the sampled traffic stream trucks of known weight recorded? Other Responses: Comment Responses: We use a form designed specifically for this purpose, along with capturing the data real-time on our laptop computers.
367 3.6.9 Are the on-site calibration using traffic stream trucks of known weight WIM error computations performed on-site? Comment Responses: If adjustments are needed, additional samples will be taken after the adjustments are made. This applies to Kistler systems only. VA-Traffic: This is done the next day in the office
368 3.6.10 During on-site calibration using traffic stream trucks of known weight how are the WIM error computations carried out? Other Responses: GA: Using a spreadsheet or other analysis program supplied by contractor Comment Responses:
369 3.6.11 For which of the following measurements are WIM errors computed? Check all that apply. Other Responses: Comment Responses: Traffic stream calibration is only used to correct drift or verify the GVW portion of normal test truck calibration procedures.
370 3.6.12 Are traffic stream trucks of known weight ever sampled for the sole purpose of determining WIM system accuracy tolerance pass/fail (e.g. new site acceptance, warranty, etc.)? Other Responses: Comment Responses:
371 3.6.13 During on-site calibration using traffic stream trucks of known weight, what method is used to compute the calibration factors? Other Responses: CT-Traffic: Auto cal & weight factor adjustment Comment Responses: More emphasis is usually given to GVW than to axle weights, but axle weights are considered as well.
372 3.6.14 During on-site calibration using traffic stream trucks of known weight do you compute calibration factors for two or more speed points? Other Responses: Comment Responses:
373 3.6.15 What remedial action is taken for WIM systems that fail to meet accuracy tolerances during traffic stream truck evaluation? Other Responses: We use a test truck to obtain a structural evaluation as well as a weight evaluation to obtain overall system performance. UT: Post collection Calibration Comment Responses: If the system cannot be corrected, WIM data will no longer be collected. If the errors are too high, then the site will be shut down.
374 What is data from systems that remain in use but fail to meet accuracy tolerances used for? Other Responses: Comment Responses: If the site cannot provide accurate count/class data, it will be shut down.
375 3.7 WIM Calibration Monitoring Using Traffic Stream WIM Data Do you use WIM calibration monitoring using traffic stream WIM data to monitor your WIM systems? Comment Responses: WIM data is processed through our office and monitored by both the office and field staff. AL-Traffic: We perodically check the steering axle weights of loaded class nine trucks KS: For peizos only.
376 3.7.1 Who conducts WIM calibration monitoring using traffic stream WIM data? Check all that apply.
377 Additional comments: MT-Traffic: In-house monitoring is conducted by both data analysis and field staff. Calibration data is processed using software developed specifically for us to perform that task. If you are outsourcing WIM calibration, you may want to ask for the contractor's assistance in responding to the following questions. 3.7.2 Typically, how often are your systems' data files downloaded? Other Responses: CT-R: At times when we had more personnel, it was weekly. Try to download monthly- except at sites if modems are working. If not working, how time permits. Every other day. Comment Responses: MT-Traffic: Higher volume sites may be downloaded as often as 3 times per week.
378 3.7.3 How are your systems' data files downloaded? Other Responses: FL: Automatically using custom polling software. CT-R: Used to use autopoll- don't recall why we stopped, but only have a few sites. At sites where there are modem/telephone issues, visit site with laptop for field download. Comment Responses:
379 3.7.4 How often do you perform checks of the WIM data? Other Responses: FL: QC edits automatically run against daily file. CT-R: When had more personnel and Department had a cooperative education program, was able to do weekly checks. Currently backlogged. WY-Traffic: Class/Count Daily, Weight Weekly Comment Responses: MT-Traffic: Data is reviewed weekly for a number of parameters. Calibration graphs are generated monthly. WA-Traffic: Or whenever data personal show possible problems they have noticed from their graphs or observations. NJ: Visual class check weekly and weight analysis monthly.
380 3.7.5 How is your WIM data analysis performed? Other Responses: FL: Realtime traffic stream data and sensor d... CT-R: Both manual and automated practices are utilized. SC: In house program WY-Traffic: Combination of both manual and automatic. ID-Traffic: Both manually and also using automatically produced reports. Comment Responses: MT-Traffic: Data is also analyzed manually if any problems are found with the automatic process, and to make sure the automatic process is checking all that it should be. ID-Traffic: This would be a good question to allow an answer of "both". We use both manual judgement, plus we pay close attention to our automatically produced reports.
381 If your data analysis is performed automatically using software, when is it carried out? Comment Responses: FL: Both actually, although the nightly QC edi... MT-Traffic: We have custom software for this procedure. WI-Traffic: Tests are performed Using TRADAS that validate the file and identifies anomalies.
382 3.7.6 In your opinion, do the analyses of your WIM data identify most system operational problems and atypical traffic characteristics? Comment Responses: MT-Traffic: Our custom software was designed, and is being upgraded as needed, to perform these functions. UT: Congestion doesn't show up well
383 If Yes, which types of system operational problems and/or atypical traffic characteristics are identified? Check all that apply. Other Responses: CT-R:Series of checks begin with file size, include the checked items above, as well as, Front Axle weight distributions for unloaded and GVW distributions for Class 9 vehicles. Finally the data is run through the LTPP data checks that includes graph MT-Traffic: Software also can generate error tracking graphs so months and years of historical operation can be viewed. WI-Traffic: Data file integrity Comment Responses: ID-Traffic: Sensor and loop related problems are most common -- sensor misses for various reasons are detected and corrected using a combination of manual observations and report analysis.
384 3.7.7 Which traffic stream vehicle types are utilized for calibration monitoring? Check all that apply. Other Responses: CT-R: Have monitored subsets of Class 9's, but only for investigations. Comment Responses: WI-Traffic: FHWA 9 for initial. If detail is desired we drill down to just 3S-2 NJ: 3s2 with front axle weight bet 8-12K and GVW bet 30-85K ID-Traffic: Empty 3S2 flatbeds are good observations. Front axles of 3S2's are also helpful. Other visable loads can be compared based on experience.
385 3.7.8 Which characteristics are monitored through WIM calibration monitoring using traffic stream WIM data? Check all that apply. Other Responses: CT-R: others only on limited investigations--- MT-Traffic: This data is also monitored for vehicles that may not meet our current classification table definitions, and need to have new definitions added. GVW Average Comment Responses:
386 3.7.9 If the monitoring of traffic stream characteristics indicates a system is experiencing calibration "drift" what action is taken? Other Responses: CT-R: Only case where that was not the case when there had been recent changes to software- check factors are correct and software was not changed. MT-Traffic: It depends on the site. Office adjustment with post-adjustment data monitoring may be sufficient. If not, on-site calibration procedures may be executed. adjust or replace manually PA: Vendor notifies that a site visit may be required Comment Responses: NJ: Calibration with test vehicle is scheduled. VA-Traffic: Data that has been affected by a known amount of calibration drift is post-processed to bring it back into line. ID-Traffic: Factors are also adjusted directly at the site.
387 3.7.10 If calibration factors are adjusted from the office, do you check the effect on the traffic characteristics described in 3.7.8? Those characteristics included: (GVW Average, GVW Average by speed, Steering axle weight average, etc.). To view a complete list click on Previous Page below. Comment Responses:
388 3.7.11 Do you keep records of WIM calibration factor adjustments? Comment Responses: MT-Traffic: Any adjustments made are recorded in a spreadsheet, and history for each site is maintained WI-Traffic: Records of initial calibration are kept.
389 If Yes, how are records kept? Comment Responses: Database calibration factor tables, and paper copies. MT-Traffic: Factors are recorded in spreadsheets for each site every time new factors are calculated, or if factors are changed for drift adjustment. Date and factors are recorded
390 Part 4: YOUR OPINION 4.1 In your opinion, are your Type I traffic data systems generating data of adequate quality to meet the requirements for the intended purposes?
391 Additional comments: MT-Traffic: The Kistler based systems generate good quality data. The two Type I systems that use MSI-BL type sensors generate adequate data. NJ: Used to maintain 4 bending plate sites and required constant maintenance which cannot be done. Data are no better than Type II sites. RI: Our data must be adaquate, I have heard of no complaints from FHWA-Washington. IL: We are not using the data, so it would be difficult to determine the quality. TX: Very satisified with bending plate data 4.2 In your opinion, are your Type I main line enforcement screening and/or sorting systems effective?
392 Additional comments: MT-Traffic: That information should be obtained from Dennis Hult at Motor Carrier Services. IL: We are not using the data, so it would be difficult to determine the effectiveness. 4.3 In your opinion, are your Type II traffic data systems generating data of adequate quality to meet the requirements for the intended purposes?
393 Additional comments: AR-Traffic: Volume and classification data are adequate, but weight data is borderline. AL-Traffic: If proper data validation, maintenance procedures and calibration schedules are followed, the accuracy is adequate for planning and pavement design purposes. TX: Not very satisifed with the coax sensors. Texas is trying hard to get away from these. 4.4 In your opinion, are your Type II main line enforcement screening and/or sorting systems effective?
394 Additional comments: MT-Traffic: Again, that information can be obtained from Dennis Hult at Motor Carrier Services. Traffic Data Collection does not maintain any Type II systems that are used as part of enforcement screening. NJ: Just in a process of starting the program. 4.5 In your opinion, given additional resources for high speed WIM traffic data collection and enforcement, which of the following would your unit consider? Check all that apply.
395 Additional comments: MT-Traffic: Our biggest need is more in-house personnel, both in the field and in the office. Unless FHWA can mandate that States must fully staff their traffic data collection programs, none of this can occur for us. WI-Traffic: Before I would consider major expansion of WIM I would focus on Classification data. In 22 years of looking at WIM data there has been very little change in average GVW or Loading. I don't see where more will tell us what we don't already know about truck loading. It is more important for us to know how many trucks are utilizing routes. MA: Imbedded axel sensors (type I piezos) frequently fail due to a variety of reasons. (epoxy/grout deterioration, improper installation procedures, etc...) UT: Our sites have been in uses for 7 years and are beginning to fail. I would like to replace with quartz AK: Staffing and timely processing of the data is very important. KS: Replace old sites that are inadequate TX: To follow the TMG guidelines, Texas has developed a plan to install WIM site per truck group and functional class of roadways 4.6 In your opinion, what is the main factor hindering proper WIM calibration and how could it be solved? FL: Time & money and qualified personnel--need more of each. CT-Research: Resources and Priorities hinder proper WIM calibration. We use the Quartz Sensors and they do not need as much calibration adjustments if they are function as designed. This is still dependent upon the roadway structure. Calibration is labor intensive and takes people and money. If the cost can be shown to be worthwhile by the need for accurate data for the applicatons, then the priority can be supported. That is why this survey needs to include how the data are used so that calibration can be economically justified. In addition, if there were more cost and less labor intensive techniques of achieving the same goals, it may become more realistic to calibrate many WIM sites. MT-Traffic: More data analysis (using computers and software) so systems can be fine-tuned to their specific environment (make up and volume of traffic stream, speed, road condition, temperature, etc.) WI-Traffic: Money. AR-Traffic: Inadequate resources to adequately perform calibration; additional funding would solve this problem. Sensors are not capable of producing accurate data over temperature variations (often over one day). Don't know how to solve this problem. Pavement type (superpave, mostly) leads to site failure; rutting is also a problem. This could be corrected by replacing asphalt with concrete at WIM sites, but again, run into funding problems. NM-Traffic: budget,having a class 9 solely for calibration WA-Traffic: To me, the main factor in achieving good WIM data is to first do a quality installation. If sensors are not installed for optimum operational characteristics your data quality will be inconistant. Also equally important is to set your Auto- calibration correctly. Pay special attention to the temperature curve, and your speed bins. It is not the matter of how many times you calibrate the sites with the known weigh trucks, in another words, if you don't set your systems right, you can calibrate your systems with known weigh trucks once a month, but you still end up with bad data. NJ: The effect of temperature change. Develop new sensors materials that are not affected by temperature change. VA-Traffic: Vehicle dynamics caused by rough pavement and calibration drift due to pavement wear. This could be solved by having smoother, more wear resistant pavement. NY: Excessive traffic volumes - no opinion on how to solve it SC: Cost of test trucks WV: Additional of second test truck and pavenment smoothness. MD-Traffic: WIM sensors that are suseptable to environmental variances in flexible pavements. MS: The main factor MDOT is faced with is maintenance issues with the equipment. PA: Road deterioration is an issue; more weight enforcement could help with this issue. MA: Insufficient staff, time, and funding to calibrate the WIM sites. A vehicle (FHWA Scheme F - Type 9) of known weight should make a minimal of five runs per lane to ensure accuracy.
396 AZ-LTPP: outdated systems, expensive to replace, not-user-friendly vendor software packages. RI: Money and Manpower AL-Traffic: Lack of qualified personnel. UT: Temperature drift CO-Traffic: Maintenance of piezo grout (better grouts for re sealing piezos)Condition of roadway surface. WY-Traffic: Autocalibration using characteristic vehicles from the traffic stream is marginal when used on many rural roadways. Solution- sensor technology not dependent on autocalibration schemes, reasonably priced with easy installation. CT-Traffic: Limited resources IN-Traffic: Road smoothness. Older sites were never properly smoothed during initial road construction. Ensure road meets ASTM smoothness specs before WIM installation. AK: Not reviewing the data on a daily basis to identify problems quickly. GA: Resources and inexperienced personnel KS: Site conditions. Pavement problems. Need concrete at every site, and long stretches without curves or cross-roads. Staff requirements make the site visits inconvenient. OK: Money. More money. ID-Traffic: Time, staff, budget requirements for a test vehicle of known weight -- with minumum of ten passes per each lane -- distant turn around at many sites -- this would take us most of the summer. TX: Equipment cost, and road conditions NH: Logistics of runing a test truck on the interstate system - turning around, changing lanes, police escort, etc. 4.7 In your opinion, what are the most urgent WIM technical needs at present and what studies need to be conducted to address them? FL: I think we know what to do and how to do it, and which equipment works well. What I need are better pavements into which the WIM sensors can be installed. CT-Research: We need to understand how the test vehicles relate to the traffic stream to better understand the data quality or assumed quality. We need to know how to relate pavement roughness to the WIM accuracy for how our pavements are actually built. The AASHTO provisional protocols are helpful but unrealistic to many pavement structures. It would be great if we could calibrate without using test trucks- perhaps through simulation programs that have been field tested. We need to know the accuracy needs of the many different data users to know what is really needed. We need nonintrusive systems or methods to "get out of the road." We need better methods to check data based on the actual vehicle configurations. We need to understand the limitation of the data and educate States on the limitation of data. We need to find best methods of sharing data between states and traffic data collection and law enforcement to improve both operations. MT-Traffic: Better, more reliable sensors. Better epoxy. Modernize the electronics to reduce power consumption and footprint. Improve communication techniques for retrieving data. Temperature of road (sensors) factored into auto- calibration routines for systems using sensors that are temperature sensitive. Better software for both office and field operations. Software needs to be modernized to work with today's operating systems, and it needs to be more user friendly, especially for those users who are not technically inclined. Sensor and epoxy studies should be a joint venture between states and vendors. Softare and communications upgrades should be performed by the vendors in response to their customers' needs. Factoring in temperature as part of maintainingcalibration on temperature sensitive sensors could also be a joint venture with states. Joint studies (vendors and states)have one major drawback--time. Since it appears that most states are understaffed in their traffic data collection areas, participation from a state standpoint would be nearly impossible to do. Once again, if FHWA truly believes that this data is important, then they need to work with state legislatures to make sure that adequate staff is obtained, not only to collect and process data, but to aid in the advancement of data collection tools and methods. WI-Traffic: I believe that there is too much money already being thrown at WIM and the same questions that were debated 20 years ago are still the same ones today. NM-Traffic: making the BL piezos last longer regardless of what kind of traffic WA-Traffic: As you all know, BL piezos are temperature and speed sensitive. I've talked to IRD to expand their temperature and speed bins, but they said there was limitation to the DOS operating system's memory. If all of us can pitch in some
397 money to pay for IRD to develope their WIM software in Windows that would be a plus. NJ: Develop more accurate sensors. VA-Traffic: Smoother, more wear resistant pavement. Sensors with reduced sensitivity to rutting. Lower cost sensors. NY: N/A SC: Sensor accuracy. Temperature and so called "auto cal" corrections to WIM data. WV: Difficulties exist with calibration of small trucks(Duals-class 5's) or less. MD-Traffic: Not sure PA: Updating to a Windows based software. PennDOT is looking intoacquiring a new version of WIM Windows based analysis software from IRD called I-analyze which can be used for all PennDOT's WIM sites. MA: Mass Highway does not utilize telemetry to poll data. We currently use Peek ADR2000's with a maximum of 8 megs storage. This limits us to three to four week studies. RIDOT has no full time AVC/WIM people. I look at wim data when/if I have the time to. UT: I need beter access to my sites. The POE sites are being eleminated and one of my eight WIM sites has no power, and none are on the net. CO-Traffic: Better grouts for piezos and for CDOT better accuracy out of our roadway sensors. WY-Traffic: From a Type II WIM perspective sensors are still the weak link. I feel fiber optics may hold promise and warrant increased study. CT-Traffic: Limited resources IN-Traffic: Constant and regular data monitoring to ensure consistent data. AK: A good database to retrieve, qc and process the data. GA: Technological improvement OK: More reliable automated data collection and analyses software. ID-Traffic: Diagnostic guidelines for calibration of WIM sites from centralized office location. TX: Selection of roadways. Types of ACP versus CRC to support WIM systems NH: Sensors and installation methods that last. Please provide any additional comments you may want to share about high speed WIM calibration. MT-Traffic: We have found, here in Montana, that not only is regular calibration important, site maintenance is also a crucial factor in obtaining consistent performance from a WIM site, reguardless of its Type. And running the entire program in- house gives us a much more controlled and consistent product. NM-Traffic: manufacturing better piezo's to last at least 5 years WA-Traffic: I've made some modification to the IRD WIM software in order to get a tigher curve: 1- Expand the temperature curve to 40 bins with 2 degree increment instead of 30 bins 5 degree increment. 2- Changed the weigh limit of the Auto- calibration type so the system does not include trucks run off the fog line or crossing the center line in the Auto-calibration process. NJ: Percentage of errors changes with temperature change. Properly calibarted system verified in the morning will have a significant error in the afternoon? Does test truck calibration really makes that much difference? PA: We try to have a minimum of 7 passes per calibration. Most times there are 10 pases. MA: Auto Cal. feature of ADR2000's is accurate. Calibration is done on steering axle, target value of 10 kips, auto cal set to adjust or compensate after 25 vehicles. IN-Traffic: Location of site should play an important part. Sites near on/off ramps or area's where traffic is changing lanes more than usual has an affect on data. ID-Traffic: We have considered the test vehicle procedures on several occasions -- even trying to estimate cost and time involved. It has never appeared practical or cost effective for us.
398 Part 5: INVENTORY OF WIM SYSTEMS This last part of the questionnaire is optional. It is an inventory of WIM systems in your state. Do you want to complete it?
399 Dual Use - A Single WIM System Used for Both Traffic Data Collection AND Enforcement Screening Approximate number of Type I WIM Systems Approximate Number of Type I WIM Lanes Sensor Type(s) 0 0 3 6 Ki stle r 0 0 0 0 0 0 0 0 0 3 10 VA-Traffic: Quartz Piezo 0 0 0 0 0 0 1 4 MS: Bending Plate 0 0 0 0 0 0 0 3 3 UT: Load cells 0 0 0 0 6 AK: bending plate and 2 load Cell 0 0 0 0 0 0 0 0 0 0 0 0 0 Single Use - Traffic Data Collection ONLY Approximate Number of Type I WIM Systems Approximate Number of Type I WIM Lanes Sensor Type(s) 7 22 FL: Bending Plate 5 CT-R: Quartz 2 4 MSI-BL sensors 1 4 WI-Traffic: PAT bending plate 0 0 0 3 12 1 2
400 0 0 4 10 VA-Traffic: 8 Lanes Quartz Piezo, 2 Lanes Bending Plate 22 0 0 0 0 0 0 0 0 0 0 11 22 AZ-LTPP: B/Plate & Piezo Sensors 0 0 0 0 0 0 0 0 2 3 KS: Ceramic, Bending Plate 0 0 0 0 0 18 40 ID-Traffic: Channel Type I and BL 12 48 TX: bending plate 0 0 Single Use - Enforcement Screening ONLY Approximate Number of Type I WIM Systems Approximate Number of Type I WIM Lanes Sensor Type(s) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
401 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Dual Use - A Single WIM System Used for Both Traffic Data Collection AND Enforcement Screening Approximate Number of Type II WIM Systems Approximate Number of Type II WIM Lanes Sensor Type(s) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 12 44 SC: piezo 0 0 15 4 MS: BL 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Single Use - Traffic Data Collection ONLY Approximate Number of Type II WIM Approximate Number of Type II Sensor Type(s)
402 Systems WIM Lanes 34 90 FL: Bending Plate, Quartz Piezo,Ceramic Piezo 24 66 ECM encapsulated sensors 10 30 WI-Traffic: Piezo 54 174 piezoelectric (linguine-type) and Quartz piezo 13 48 32 90 65 260 0 0 0 0 0 0 6 6 MD-Traffic: BL Piezo sensor 0 0 8 9 PA: kistler-loop-kistler 12 30 MA: Piezo, Loop Piezo 7 7 AZ LTPP: Piezo 9 56 UT: Piezo 16 62 9 22 WY-Traffic: Piezoelectric 0 0 8 17 KS: piezo-cable 30 2 TN: Diamond Traffic Piezos 20 76 OK: Piezo 0 0 4 16 TX: piezo 4 18 NH: Piezoelectric Single Use - Enforcement Screening ONLY Approximate Number of Type II WIM Systems Approximate Number of Type II WIM Lanes Sensor Type(s) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
403 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Approximate Number of Type II WIM Systems (Single Use - Enforcement Screening ONLY)
404 Generated: 6/2/2007 12:48:02 PM
