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From page 71... ... The tools described in this appendix require data with varying levels of detail, ranging from TAZ level information in the Planning Level Safety Prediction Model to fairly detailed input in the IHSDM. The tools also vary in terms of purpose: the Planning Level Safety Prediction Model is used to perform safety prediction by TAZ area (pro-active) Read the entire page →
From page 72... ... Reactive: Generate medical and financial outcome information related to motor vehicle accidents High: Accident Data Emergency Service Data Hospital Inpatient Data Death Certificate Data Vehicle Identification Number Data Trauma Registry Data Statistical analysis, use of the CODES linkage software Interactive Highway Safety Design Model (IHSDM) Pro-active and reactive. Read the entire page →
From page 73... ... Cost effectiveness analysis to assess effectiveness of roadside safety improvements Moderate: Accident Data Geometry of existing roadway Basic understanding of traffic engineering and Monte Carlo simulation technique. SafeNET Pro-active and reactive, Traffic accident prediction for intersections and sections Differs depending on purpose: Basic: traffic flows averaged over day More detailed: vehicle flow, pedestrian flow, site characteristics, specific geometric features, junction turning flows, and other design features Basic traffic engineering, accident modeling, 4-step planning models SafetyAnalyst Reactive but some proactive applications: Analysis of accident data: by site, by section or systemwide Moderate: Accident data Geometric, traffic, weather, and human attributes Statistical analysis & basics of traffic engineering Appendix C: Safety Tools 93 Read the entire page →
From page 74... ... Prediction of accidents by Traffic Analysis Zone (TAZ) Moderate to High: Accident data Census data Bicycle and transit facility locations Functional Classification of road network Statistical Analysis and the use of GIS software: expertise required for GIS analysis will depend on the nature of existing GIS information and databases. Read the entire page →
From page 75... ... These project alternatives are ranked by benefit-cost ratios and project details are formatted to supplement HES eligibility applications. With these features, the Arizona LGSP model supports local governments in Arizona to address their highway safety needs on a timelier basis, and ensure that more attention is directed at the most hazardous locations, thereby improving the overall safety of the roadway system. Read the entire page →
From page 76... ... Incorporating Safety into Long-Range Transportation-Planning Exhibit 55: Arizona LGSP analysis set-up window Exhibit 56: Arizona LGSP analysis parameters window Appendix C: Safety Tools 96 Read the entire page →
From page 77... ... A synthesis on statistical methods in highway safety analysis presented a more elaborate statistical treatise on conventional before-after studies [Griffin and Flowers, 1997] Read the entire page →
From page 78... ... Further information is provided in Hauer, 1999. Appendix C: Safety Tools 98 Read the entire page →
From page 79... ... Department of Transportation, National Highway Traffic Safety Administration. Brief description of transportation safety applications: CODES was designed to generate crash statistics that merge medical and financial outcome information with motor vehicle accidents. Read the entire page →
From page 80... ... For further examples, refer to the software website: http://care.cs.ua.edu. Exhibit 61: Example output from CARE Appendix C: Safety Tools 100 Read the entire page →
From page 81... ... The IHSDM can also be used to present graphical representations of an analyzed roadway showing plan, profile, and cross-sectional views. Appendix C: Safety Tools 101 Read the entire page →
From page 82... ... Appendix C: Safety Tools 102 Read the entire page →
From page 83... ... Examples of Analysis using IM To demonstrate the various accident analysis features available in IM, a set of analysis examples are provided using accident data from City of Chandler, Arizona. It should be noted that this software description do not intend to substitute for the IM manual; it merely intends to demonstrate by example some of the analysis capabilities of the software. Read the entire page →
From page 84... ... Incorporating Safety into Long-Range Transportation-Planning Appendix C: Safety Tools option Diagram/Accidents/Toggle highlighter and then choosing specific colors to represent typical accident types. Exhibit 64: Screen grab for top 100 Intersections with at least one accident Exhibit 65: Screen grab for Alma School & Warner Road intersection accident diagram 104 Read the entire page →
From page 85... ... Exhibit 66: Screen grab for Evergreen St & Warner Road intersection accident diagram with labels IM's filter tool helps analyst extracting specific attribute of accident from the database. Read the entire page →
From page 86... ... Specifically, for each specified road, this function examines the entire length and sorts the high accident locations into the list of all roads specified for processing. Appendix C: Safety Tools 106 Read the entire page →
From page 87... ... . As an effort to develop Highway Safety Manual (HSM) Read the entire page →
From page 88... ... However, LOSS concept is intended to reflect the performance in terms of expected accident frequency and severity at a specific level of AADT, as opposed to the measure of delay, conventional in the Level of Service Analysis. Safety Performance Function (SPF) Read the entire page →
From page 89... ... • Segment #2, however, showed highly undesirable safety performance in the high range of the LOSS-IV for both frequency and severity, which suggested a high potential for accident reduction. At this stage of the diagnostic investigation, the researchers concluded that the site experienced significantly more accidents than expected for some unknown Appendix C: Safety Tools 109 Read the entire page →
From page 90... ... More specifically, it triggered rear-end and sideswipe collisions. Appendix C: Safety Tools 110 Read the entire page →
From page 91... ... Exhibit 72: Breakdown by accident type in the study area Appendix C: Safety Tools 111 Read the entire page →
From page 92... ... Incorporating Safety into Long-Range Transportation-Planning Exhibit 73: Wave type CLOSS analysis for total accidents Researchers identified a highly constrained weave type C section within segment #2 in the southbound direction which contributed to the higher number of rear-end and sideswipe collisions Exhibit 74: Wave type CLOSS analysis for injury and fatal accidents Appendix C: Safety Tools 112 Read the entire page →
From page 93... ... Appendix C: Safety Tools 113 Read the entire page →
From page 94... ... The Road Characteristics Database and the Accident Database are the two most important data sources for the highway and pedestrian/bicycle analyses. Other information is provided from current statewide modal transportation plans. Read the entire page →
From page 95... ... Appendix C: Safety Tools 115 Read the entire page →
From page 96... ... Brief description of transportation safety applications: The PBCAT is utilized to develop and analyze databases containing details associated with accidents between motor vehicles and pedestrians or bicyclists. The tool includes "accident type", which describes the actions of the parties involved immediately prior to the accident. Read the entire page →
From page 97... ... Incorporating Safety into Long-Range Transportation-Planning Exhibit 77: PBCAT style and navigation window Version 1 Crash Typing Exhibit 78: PBCAT style and navigation window Appendix C: Safety Tools 117 Read the entire page →
From page 98... ... Brief description of transportation safety applications: The PEDSAFE prototype is currently under beta testing and will incorporate the content of the FHWA Pedestrian Facilities User Guide into a system that allows the user to select appropriate countermeasures or treatments to address specific safety problems for pedestrians. PEDSAFE also includes a large number of case studies to illustrate treatments implemented in several communities throughout the United States and Europe. Read the entire page →
From page 99... ... and User's Manual are available from the Transportation Research Board. The purpose of this section is to briefly describe the methodology used by RSAP using Appendix A of the AASHTO Roadside Design Guide as reference. Read the entire page →
From page 100... ... – User's Manual, National Cooperative Highway Research Program Project 22-9: Improved Procedures for Cost-Effectiveness Analysis of Roadside Safety Features, Transportation Research Board, Washington D.C., 2002. Appendix C: Safety Tools 120 Read the entire page →
From page 101... ... Example application of tool: A description of the software as provided on the website of UK Department for Transport under "Traffic Advisory Leaflet, 08/99: Urban Safety Management: Using SafeNET" is provided below. A road network in a typical SafeNET window is shown in Exhibit 82. Read the entire page →
From page 102... ... The link between the traffic assignment and impact on safety makes it easy to account for interactions between traffic volumes, safety, and mobility. In particular, the process allows rapid adjustment of the flows, which yield key inputs to the accident prediction models. Read the entire page →
From page 103... ... SafetyAnalyst will incorporate state-of-the-art safety management approaches into computerized analytical tools for guiding the decision-making process to identify safety improvement needs and develop a system wide program of site-specific improvement projects." In addition, SafetyAnalyst can be used for cost-effectiveness analysis of safety improvements to ensure that highway agencies get the greatest possible safety benefit from each dollar spent in the name of safety. SafetyAnalyst consists of six software programs to analyze the safety performance of specific sites, to suggest appropriate countermeasures, quantify their expected benefits and to evaluate their effectiveness. Read the entire page →
From page 104... ... As a result of extensive research on highway safety and statistical analysis over last 20 years, SafetyAnalyst software will implement these new approaches in its network screening. For example, the Empirical Bayes (EB) Read the entire page →
From page 105... ... The analyses will include appropriate consideration of the service life of the countermeasure and the time value of money. This tool is capable of performing economic analyses consistent with the requirements of the Federal Highway Safety Improvement Program (HSIP) Read the entire page →
From page 106... ... This tool will also provide, where appropriate, users with the ability to perform before-after evaluations using statistical techniques other than the EB approach. Appendix C: Safety Tools 126 Read the entire page →
From page 107... ... See http://transims.tsasa.lanl.gov/ for more details. Brief description of transportation safety applications: TRANSIMS is an integrated system of travel forecasting models designed to give transportation planners accurate, complete information on traffic impacts, congestion, and pollution. Read the entire page →
From page 108... ... In addition, it can make better volume predictions along the network, which in turn is useful for safety analysis. Appendix C: Safety Tools 128 Read the entire page →
From page 109... ... Planning level safety prediction models are fundamentally different in nature to corridor or site specific crash prediction models because; 1) The input data are aggregate and not site or project specific; 2) Read the entire page →
From page 110... ... HTU simon.washington@asu.eduUTH . Brief description of transportation safety applications: The Planning Level Safety Prediction Model is a planning-level model used to predict motor vehicle accidents per traffic analysis zone (TAZ) Read the entire page →
From page 111... ... Thus, for example, if a population variable is used to predict fatal crashes per TAZ, its estimated coefficient is used solely in the prediction equation but is not interpreted to have specific explanatory marginal effects. Appendix C: Safety Tools 131 Read the entire page →
From page 112... ... The PLANSAFE model is appropriate for forecasting the future expected safety performance of these projects in the absence o targeted safety counte measu es. f r r Given that a future project will influence the forecasting variables in the PLANSAFE model, the PLANSAFE model will produce a prediction of the effect of the project on safety (i.e., crashes of various types) Read the entire page →
From page 113... ... Thus, at this time the PLANSAFE model includes the ability to predict eight safety-related outcome variables as a function of various predictor variables. Appendix C: Safety Tools 133 Read the entire page →
From page 114... ... Fatal Accident Frequency Model INT_PMI Number of intersections per mile (using total mileage in the TAZ) PNF_0111 Total mileage of urban and rural interstates as a portion of the total mileage (federal functional classifications 01 and 11) Read the entire page →
From page 115... ... VARIABLE COEFFICIENTS t-STATISTIC Total Accident Frequency Model* POP_PAC 0.474 x 10P-1P 9.067 POP16_64 0.196 x 10P-3P 36.373 TOT_MILE 0.151 x 10P-2P 3.482 Property Damage Only Accident Frequency Model* Read the entire page →
From page 116... ... 64_1610196.0_10 0.474020.5 3-1 POPPACPOP −×+×+= ( ) MILETOT _10151.0 2−×+ Property Damage Only Accident Frequency Model ) Read the entire page →
From page 117... ... It is likely that this population based variable captures both the aggregate population effect as well as the ‘activity' factor associated with families with young children. Discussion 2: Frequency of Accidents Involving Pedestrians The pedestrian crash prediction model is given as: ) Read the entire page →
From page 118... ... Exhibit 94 and Exhibit 95 illustrate the predicted relationships between pedestrian-related Appendix C: Safety Tools 138 Read the entire page →
From page 119... ... Thus, one would not interpret a change in one of the predictor variables as a marginal Appendix C: Safety Tools 139 Read the entire page →
From page 120... ... How to Apply PLANSAFE Models The PLANSAFE Models are used to forecast safety in future periods or for various project/build scenarios at the TAZ level, as described previously. The same variables (data) Read the entire page →
From page 121... ... The next step is to compute the average BCF across TAZs, using ∑ = = toNi i i average P OBCF 1 . The standard deviation and coefficient of variation of individual BCFs are then calculated to enable goodness of fit assessment and comparison across PLANSAFE models. Read the entire page →
From page 122... ... UStep 1 U: An analyst has decided to apply the PLANSAFE Incapacitating and Fatal Injury Crash Frequency Model to make predictions across 10 TAZs within a jurisdiction. A major corridor improvement is being considered, which will bring about new residential and commercial development to the 10 TAZs, as well as traffic volumes and associated activity. Read the entire page →
From page 123... ... In this example, the PLANSAFE model is under-predicting incapacitating and fatal injury crashes, on average, by a factor of about 1.6. This under-prediction is the result of multiple potential factors that are not included in the prediction models, including differences in weather (e.g., wet, ice, snow, and fog conditions) Read the entire page →
From page 124... ... Exhibit 98: Predicted future incapacitating and fatal crashes for PLANSAFE example application TAZ Predicted Project Scenario Crash Frequency BCF Adjusted Project Scenario Crash Frequency 1 5.70 1.594 9.09 2 7.39 1.594 11.79 3 5.36 1.594 8.54 4 9.02 1.594 14.37 5 4.34 1.594 6.91 6 3.28 1.594 5.24 7 3.83 1.594 6.11 8 3.84 1.594 6.13 9 6.25 1.594 9.96 10 5.76 1.594 9.18 Total 87.31 The increase in expected crashes that results from the project is not an argument in of itself for or against the project, and in fact is merely an informative statement regarding safety and not a value statement about safety. That incapacitating and fatal crashes are predicted to increase from 68 to 87.31 merely represents an increase in injury severity risk expected by increases in the number of intersections, residential development, road mileage, and local population increases. Read the entire page →
From page 125... ... Incorporating Safety into Long-Range Transportation-Planning with a tool for setting targets for meeting safety objectives and performance milestones. Appendix C: Safety Tools 145 Read the entire page →
From page 126... ... Incorporating Safety into Long-Range Transportation-Planning Page left intentionally blank. Appendix C: Safety Tools 146 Read the entire page →

From page 71...

... The tools described in this appendix require data with varying levels of detail, ranging from TAZ level information in the Planning Level Safety Prediction Model to fairly detailed input in the IHSDM. The tools also vary in terms of purpose: the Planning Level Safety Prediction Model is used to perform safety prediction by TAZ area (pro-active)