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Highway and Street Design Vehicles: An Update (2023)

Chapter: Chapter 3 - Survey of Transportation Agencies

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Suggested Citation:"Chapter 3 - Survey of Transportation Agencies." National Research Council. 2023. Highway and Street Design Vehicles: An Update. Washington, DC: The National Academies Press. doi: 10.17226/27236.
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Suggested Citation:"Chapter 3 - Survey of Transportation Agencies." National Research Council. 2023. Highway and Street Design Vehicles: An Update. Washington, DC: The National Academies Press. doi: 10.17226/27236.
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Suggested Citation:"Chapter 3 - Survey of Transportation Agencies." National Research Council. 2023. Highway and Street Design Vehicles: An Update. Washington, DC: The National Academies Press. doi: 10.17226/27236.
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Suggested Citation:"Chapter 3 - Survey of Transportation Agencies." National Research Council. 2023. Highway and Street Design Vehicles: An Update. Washington, DC: The National Academies Press. doi: 10.17226/27236.
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Suggested Citation:"Chapter 3 - Survey of Transportation Agencies." National Research Council. 2023. Highway and Street Design Vehicles: An Update. Washington, DC: The National Academies Press. doi: 10.17226/27236.
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Suggested Citation:"Chapter 3 - Survey of Transportation Agencies." National Research Council. 2023. Highway and Street Design Vehicles: An Update. Washington, DC: The National Academies Press. doi: 10.17226/27236.
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Suggested Citation:"Chapter 3 - Survey of Transportation Agencies." National Research Council. 2023. Highway and Street Design Vehicles: An Update. Washington, DC: The National Academies Press. doi: 10.17226/27236.
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Suggested Citation:"Chapter 3 - Survey of Transportation Agencies." National Research Council. 2023. Highway and Street Design Vehicles: An Update. Washington, DC: The National Academies Press. doi: 10.17226/27236.
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Suggested Citation:"Chapter 3 - Survey of Transportation Agencies." National Research Council. 2023. Highway and Street Design Vehicles: An Update. Washington, DC: The National Academies Press. doi: 10.17226/27236.
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Suggested Citation:"Chapter 3 - Survey of Transportation Agencies." National Research Council. 2023. Highway and Street Design Vehicles: An Update. Washington, DC: The National Academies Press. doi: 10.17226/27236.
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Suggested Citation:"Chapter 3 - Survey of Transportation Agencies." National Research Council. 2023. Highway and Street Design Vehicles: An Update. Washington, DC: The National Academies Press. doi: 10.17226/27236.
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Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

20 This chapter presents the results of a survey of transportation agencies concerning design vehicles that was conducted as part of the research. The questionnaire developed for the survey of transportation agencies consisted of 15 ques- tions and is presented in Appendix A. The results obtained from the survey are presented in Sections 3.2.1 through 3.2.15. 3.1 Survey Distribution List and Response Rate The survey was conducted electronically using Survey Monkey® software. The survey was sent to design engineers in each of the 50 state departments of transportation (DOTs); design or traffic engineers in 273 local agencies; management personnel in 57 turnpike, toll bridge, and tunnel authorities; and the three FHWA Federal Lands Highway Regional Offices. The state DOT representatives included members of the AASHTO Technical Committee on Geometric Design, the AASHTO Committee on Design, and the NCHRP Project 07-27 panel. Reminders were sent on two occasions to all agencies that had not yet responded. Responses were received from 24 of the 50 state DOTs (48.0%); 9 of the 273 local agencies (3.3%); 2 of the 57 turnpike, toll bridge, and tunnel authorities (3.5%); and none of the Federal Lands Highway Offices. A response was also received from one transit agency. The overall response rate was 35 responses out of the total of 383 surveys sent (9.1%). Figure 11 illustrates the locations of the agencies that responded to the survey. Responding states have been filled in on the map. The locations of responding local agencies and turnpike, toll bridge, and tunnel authorities are represented by dots or small squares on the map. 3.2 Questionnaire Responses 3.2.1 Question 1—What Type of Transportation Agency Do You Represent? Question 1 asked each respondent to indicate the type of transportation agency they represent. The discussion of the survey response rate in Section 3.2 summarizes the responses to Question 1. 3.2.2 Question 2—Which of the Design Vehicles in the Current (2018) Edition of the AASHTO Green Book Does Your Agency Apply in the Design of Projects under Your Agency’s Jurisdiction? Question 2 asked respondents in transportation agencies which of the design vehicles in the current Green Book their agency has used in the design of projects under their jurisdiction. C H A P T E R 3 Survey of Transportation Agencies

Survey of Transportation Agencies 21 The responses shown in Table 3 add up to more than 100% because agencies were free to make multiple responses. The most used of the current design vehicles were the P (passenger car) and WB-67 (interstate semitrailer combination truck with a single 53-ft trailer), which have both been used by 30 of the 35 responding agencies. The least used design vehicle was the WB-92D (Rocky Mountain double combination truck), which has been used by two of the responding agencies. The responses show that each of the current design vehicles has been applied in the design of projects, where needed. The design vehicles that have been used least are the double- and Figure 11. Transportation agencies that responded to the survey. Design vehicle Number (percent) ofrespondents P Passenger car 30 (88.2) SU-30 Single-unit truck (two-axle) 28 (82.4) SU-40 Single-unit truck (three-axle) 22 (64.7) Bus-40 Intercity bus (motor coach) 16 (47.1) Bus-45 Intercity bus (motor coach) 13 (38.2) CITY-BUS City transit bus 18 (52.9) S-BUS-36 Conventional school bus (65 passengers) 21 (61.8) S-BUS-40 Large school bus (84 passengers) 18 (52.4) A-BUS Articulated bus 10 (29.4) WB-40 Intermediate semitrailer (33-ft trailer) 18 (52.9) WB-62 Interstate semitrailer (48-ft trailer) 25 (73.5) WB-67 Interstate semitrailer (53-ft trailer) 30 (88.2) WB-67D Double bottom semitrailer/trailer (28.5-ft twin) 9 (26.5) WB-92D Rocky Mountain double semitrailer/trailer 2 (5.9) WB-100T Triple semitrailer/trailer 3 (8.8) WB-109D Turnpike double semitrailer/trailer 5 (14.7) MH Motor home 13 (38.2) P/T Car and camper trailer 16 (47.1) P/B Car and boat trailer 15 (44.1) MH/B Motor home and boat trailer 11 (32.4) Table 3. Design vehicles applied in the design of projects.

22 Highway and Street Design Vehicles: An Update triple-trailer trucks. Some of these vehicles have offtracking equivalent to the WB-67 design vehicle (and, therefore, may not often be needed), while others only operate in a few states (see Sections 5.6 and 5.7). 3.2.3 Question 3—Are Trucks Larger Than the WB-67 Single-Trailer Truck or the WB-67D Twin-Trailer Truck Allowed to Operate without Permits or with Routinely Issued Permits on Roads Maintained by Your Agency? Question 3 asked transportation agency respondents whether trucks larger than the WB-67 single-trailer truck or the WB-67D twin-trailer truck are allowed to operate without permits or with routinely issued permits on roads maintained by their agency. Table 4 shows that 20% of respondents said that such trucks are allowed to operate in their jurisdiction, 40% of respon- dents indicated that such trucks are not allowed to operate in their jurisdiction, and 40% of respondents indicated that they did not know whether such trucks are allowed to operate on roads in their jurisdiction. Respondents that indicated “YES” were asked to identify the specific truck configurations allowed and the situations in which they are allowed to operate. Sections 5.5 through 5.7 provide details about single-trailer trucks larger than the WB-67 design vehicle and multitrailer trucks larger than the WB-67D design vehicle that are allowed to operate in specific states. 3.2.4 Question 4—Do You Believe the Dimensions or Turning Radii of Any of the Current AASHTO Green Book Design Vehicles Need Updating? Question 4 asked respondents whether they believe the dimensions or turning radii of any of the current Green Book design vehicles need updating. Table 5 shows that 20% of respondents indicated that there were design vehicles in need of updating, 51% of respondents indicated that there were not any design vehicles in need of updating, and 29% of respondents indicated that they didn’t know or had no opinion. Respondents that indicated “YES” were asked to identify the specific truck configurations in need of updating and to explain why they believe that the design vehicle’s dimensions and/or turning radii need updating. The responses received to this inquiry were as follows: • As the Manual on Assessing Safety Hardware (MASH) requires, a periodic review and update of the most common vehicle size under each category are needed [e.g., pickup trucks (the largest Response Number (percent) of respondents Yes 7 (20.0) No 14 (40.0) Don’t know/No opinion 14 (40.0) TOTAL 35 (100.0) Table 4. Operation of trucks larger than WB-67 or WB-67D. Response Number (percent) of respondents Yes 7 (20.0) No 18 (51.4) Don’t know/No opinion 10 (28.6) TOTAL 35 (100.0) Table 5. Updating of dimensions or turning radii needed.

Survey of Transportation Agencies 23 group of vehicles sold)] (AASHTO 2016). It may be a good idea to replace the P design vehicle with a pickup truck and continue with the flexibility on design based on pickup truck size to determine lane widths less than 12 ft. • We use WB-62 for designing state roads and, for roundabouts, the templates/programs seem to be very conservative causing us to build much larger truck aprons than actually needed once the roundabout is operating. We can’t figure it out, and we have looked into all the parameters extensively. • Yes. Although our agency has not had any major issues with the current Green Book design vehicles, it is understood that there have been issues as noted in the background information of NCHRP Project 07-27. • Although the larger vehicles are most consequential to intersection design and should be the top priority, a review of all AASHTO vehicles should be conducted to verify or revise key dimensions, including and especially the outside turning radius (OTR). Even passenger car turning characteristics are pertinent to urban street design (e.g., for U-turns and maneuvers into/out of parking bays). • Larger trucks are conservative in the Green Book. Trucks have better turning radii than currently depicted. • Common tractor wheelbases are longer in our state, therefore requiring a larger turning radius. • Does the current library of vehicles still make sense with today’s fleet? Why are some of the combinations shown with a sleeper tractor and others with a cab-only tractor? Are the tractors shown representative of the tractors in use today? They seem too small. Why is the centerline turning radius of the WB40 equal to 36.0 ft, the WB67 equal to 41.0 ft, and the WB92D equal to 78.0 ft? Most of the turn templates appear to produce turning movements that are much larger than what we observe in the field. 3.2.5 Question 5—Are There Any Design Vehicles That Your Agency Would Like Added to the AASHTO Green Book? Question 5 asked respondents to indicate whether there are any design vehicles that their agency would like to see added to the Green Book. Table 6 shows that 40% of respondents said yes, 51% of respondents said no, and 9% said that they didn’t know or had no opinion. Respondents that indicated “YES” were asked to identify the specific design vehicles that should be added and describe why they thought they should be added. The responses to this inquiry were as follows: • It may be a good idea to replace P with a pickup truck (largest sale bracket) and continue with the flexibility on design based on pickup truck size to determine lane widths less than 12 ft. • A pickup truck/boat and pickup truck/trailer would be a good addition. We typically do not see passenger cars towing boats or trailers in our state. • If the multi-rear-tandem grain truck ends up having different OTR characteristics than the SU-40, it or something representing that family of vehicles should be added. Its turning radius is typically the controlling factor for the design of U-turn accommodations at rural reduced- conflict intersections. Response Number (percent) of respondents Yes 14 (40.0) No 18 (51.4) Don’t know/No opinion 3 (8.6) TOTAL 35 (100.0) Table 6. Design vehicles transportation agencies would like added to the Green Book.

24 Highway and Street Design Vehicles: An Update • Five agencies stated that fire trucks or other emergency vehicles should be considered; one additional state asked whether an existing design vehicle could be used to represent fire trucks and ambulances. • Vehicles associated with hauling construction equipment. • Restore the WB-50 design vehicle (Note: This vehicle was dropped from the 2011 Green Book because combination trucks of this size are no longer common on the U.S. road network.). • “Low-boy” semitrailers—very common in agricultural areas to transport farm and construction equipment. • The double-trailer combination with 81.5-ft maximum length with a 45-ft maximum trailer length. • Semitrailer truck with dolly, such as those used for hauling wind-turbine blades 100 ft or more in length. • Not necessarily a specific design vehicle, but discussion or potentially a table in the Green Book that assists in vertical clearance/profile elements. For example, a sag vertical with a vertical clearance issue such as a railroad overcrossing. This may be outside of the project funding allotment. 3.2.6 Question 6—Does Your Agency Design to Accommodate Any Vehicles That Are Not Currently in the Green Book by Using an Existing Green Book Design Vehicle to Approximate Its Turning Performance? Question 6 asked respondents whether their agency accommodates any vehicles that are not currently in the Green Book by using an existing Green Book design vehicle to approximate its turning performance. Table 7 shows that 46% of respondents said yes, 51% of respondents said no, and 3% said that they didn’t know or had no opinion. Respondents that indicated “YES” were asked to describe the situation(s) in which their agency uses an existing design vehicle to represent the performance of another vehicle. The responses to this inquiry were as follows: • We modify the wheelbase of P/T and P/B vehicles to represent pickup truck/trailer and pickup truck/boat combinations. • Six agencies indicated that they approximate the turning performance of fire trucks, other emergency vehicles, or maintenance vehicles of other agencies. One respondent stated that their agency uses the SU-40 design vehicle to approximate a fire truck, while another indicated that their agency uses a bus of similar length and wheelbase. • One agency stated that they simply use the best approximation of the vehicle. • One agency indicated that they use approximations for operational reviews, but not for design. • Seven agencies responded by indicating specific vehicles that they have used in turning template software, rather than approximating them with a current design vehicle. These include the following: – Custom tractor-trailer sizes (but these are not needed in the Green Book) – Fire trucks Response Number (percent) of respondents Yes 16 (45.7) No 18 (51.4) Don’t know/No opinion 1 (2.9) TOTAL 35 (100.0) Table 7. Transportation agencies designing to accommodate vehicles not in the Green Book.

Survey of Transportation Agencies 25 – Trucks hauling large cranes – Trucks hauling wind turbines and wind-turbine blades – Grain-hauling trucks – Double-trailer combination with a maximum trailer combination length of 81.5 ft, plus several others – Specific vehicles that enter a particular site 3.2.7 Question 7—Are There Any of the Current AASHTO Green Book Design Vehicles That You Believe Are Not Needed and That Should Be Dropped from the AASHTO Green Book? Question 7 asked respondents if there are any of the current Green Book design vehicles that they believe are not needed and that should be dropped from the Green Book. Table 8 shows that 6% of respondents said yes, 51% of respondents said no, and 43% said that they didn’t know or had no opinion. Respondents that indicated “YES” were asked to identify the design vehicles that are not needed and that should be dropped. Some respondents that gave responses other than “YES” also offered their opinions. The responses to this inquiry were as follows: • This research should reveal the most common vehicles occupying the system currently. This decision shall be based on data rather than an opinion. • Certain projects may call for us to check the design vehicles that are there but not commonly used. I would leave them. • The range of vehicles shown in the Green Book has been adequate for our purposes. • We have not used recreational vehicles, such as motor homes, camper trailers, or boat trailers, for the design of the state highway system. Other agencies may use these. • Six bus templates seem excessive. A prudent designer would pick a conservative design vehicle (bus) knowing that the city could update buses down the road, so the lesser designs could be eliminated. Our agency does not have a bus template and we’ve found the SU-40 is more conservative (i.e., would accommodate most bus scenarios), excluding bike rack consider- ations. Similarly, the car hauling a boat doesn’t seem like it would ever be used. If a designer is accommodating recreational vehicles such as this, using the car hauling a trailer should be the prudent and minimum design. 3.2.8 Question 8—Are There Additional Dimensions, Parameter Values, or Discussion Text Concerning Design Vehicles or Their Application That You Believe Should Be Added to the AASHTO Green Book? Question 8 asked respondents if there are additional dimensions, parameter values, or discussion text concerning design vehicles or their application that should be added to the Green Book. Table 9 shows that 26% of respondents said yes, 50% of respondents said no, and 24% said that they didn’t know or had no opinion. Response Number (percent) of respondents Yes 2 (5.7) No 18 (51.4) Don’t know/No opinion 15 (42.9) TOTAL 35 (100.0) Table 8. Design vehicles not needed by transportation agencies.

26 Highway and Street Design Vehicles: An Update Respondents that indicated “YES” were asked to describe the information to be added and the reason it is needed. The responses to this inquiry were as follows: • The increased dimensions of pickup trucks are a concern since they are the most representative type of vehicle on roadways currently. • How accurate are the templates? We are overbuilding our truck aprons on our roundabouts. • Added/additional emphasis on the turn speed on which turn paths/needs are evaluated. • More and better guidance on reasonable design assumptions would be valuable (e.g., under what circumstances is encroachment essential versus acceptable versus inadvisable). Also, an urban intersection design approach that is a balance between accommodating infrequent large vehicles and designing for the safety and ease of use for vulnerable users—rather than hierarchal, where the large infrequent vehicles determine the size and design of the inter- sections, and all other users are forced to deal with it. • Yes. Section 2.1.1 (General Characteristics) last paragraph on page 2-5 of the 2011 Green Book. . . . Consider elaboration on the discussion of larger vehicles. For example, the develop- ment of wind power (large turbines, etc.) and the different size of loads has led to very specific turning requirements and analysis to determine how these large vehicles achieve their final destination. • Vertical clearances are needed to assist with preventing high-centered issues, particularly with roundabouts. • The truck tractor wheelbase shown in AASHTO is smaller than that in our agency’s design manual. • The selection of a design vehicle appears to have a large effect on roundabout design. Some discussion on design for a certain vehicle versus accommodation of that vehicle would be helpful. • Approximate weight (tons empty). • Discussion about the placement of trees at intersections. 3.2.9 Question 9—Does Your Agency Have Any Internal Guidelines on Selecting a Design Vehicle for a Particular Roadway Type or Project? Question 9 asked respondents whether their agency has any internal guidelines on selecting a design vehicle for a particular roadway type or project. Table 10 shows that 66% of respondents said yes, 34% of respondents said no, and none said that they didn’t know or had no opinion. Response Number (percent) of respondents Yes 9 (26.5) No 17 (50.0) Don’t know/No opinion 8 (23.4) TOTAL 34 (100.0) Table 9. Need for additional dimensions, parameter values, or discussion to be added to the Green Book. Response Number (percent) of respondents Yes 23 (65.7) No 12 (34.3) Don’t know/No opinion 0 (0.0) TOTAL 35 (100.0) Table 10. Transportation agencies with internal guidelines on selecting design vehicles for projects.

Survey of Transportation Agencies 27 Respondents that indicated “YES” were asked to refer the research team to a source for that guidance, such as a particular section of their agency’s design manual. The responses to this inquiry were as follows: • The design vehicle for interstate and NHS routes is WB-67. The design vehicle for other routes will require evaluation by the designer. We do show SU-40 for speeds lower than 45 mph. • We typically use WB-40 for all roadways. Depending on the situation, we may use a WB-67. • We are working on incorporating this into our design criteria manual, but it is often deter- mined on a case-by-case basis depending on the surrounding land uses and development. • Sixteen agencies cited specific sections of their design manual that were reviewed in the research. 3.2.10 Question 10—Does Your Agency Have Any Internal Guidelines for Allowing Occasional Encroachment of a Turning Vehicle into Adjacent Lanes, Curbing, or Sidewalks? Question 10 asked respondents whether their agency has any internal guidelines for allow- ing occasional encroachment of a turning vehicle into adjacent lanes, curbing, or sidewalks. Table 11 shows that 40% of respondents said yes, 60% of respondents said no, and none said that they didn’t know or had no opinion. Respondents that indicated “YES” were asked to refer the research team to a source for that guidance, such as a particular section of their agency’s design manual: • We regularly design for larger vehicles to utilize all lanes rather than turning into only the outside lane of a multilane facility. This shrinks the footprint (right-of-way, pedestrians). Allowance for further encroachment is on a case-by-case basis. • We typically allow vehicles to encroach when turning onto a roadway with two lanes in one direction; otherwise, this is not allowed. • Encroachment allowed onto adjacent/opposing lanes, but not curbing or sidewalks. • Encroachment is allowed onto adjacent lanes and shoulders only. • We do rely on the engineer to use judgment in those scenarios. • Not in the design manual. Usually a District determination. • Case-by-case basis. No policy, per se. • Nothing in writing. • Ten agencies cited specific sections of their design manual, which the research team reviewed when formulating design guidance in Task 5 of the project. 3.2.11 Question 11—What Turning Template Software Does Your Agency Use in Designing Intersections or Other Roadway Elements to Accommodate Specific Design Vehicles? Question 11 asked respondents what turning template software their agency uses in designing intersections or other roadway elements to accommodate specific design vehicles. Table 12 shows Response Number (percent) of respondents Yes 14 (40.0) No 21 (60.0) Don’t know/No opinion 0 (0.0) TOTAL 35 (100.0) Table 11. Transportation agencies with internal guidelines for allowing occasional encroachment of a turning vehicle.

28 Highway and Street Design Vehicles: An Update that 83% of responding agencies use AutoTURN, 20% of responding agencies use Autodesk Vehicle Tracking, and 3% of responding agencies said that they use other software. The responses in Table 12 sum to more than 100.0% because some agencies use more than one software package. The responding agency that indicated “other” uses Bentley/Microstation® tools, as well as AutoTURN on a limited basis. One agency indicated that they use templates printed to scale on clear Mylar that can be overlaid on submitted designs. 3.2.12 Question 12—Should the Manner in Which the Turning Vehicle Templates for Design Vehicles Are Presented in the AASHTO Green Book Remain the Same or Change, Keeping in Mind That Many Designers Use Commercial Turning Template Software Rather than the Turning Templates in the Green Book? Question 12 asked respondents whether the manner in which turning vehicle templates are presented in the Green Book should remain the same or change, keeping in mind that many designers use commercial turning template software rather than the turning templates in the Green Book. Table 13 shows that 74% of respondents indicated that the Green Book should retain turning template drawings for every design vehicle, while 26% of respondents indicated that the Green Book should show one or two turning template drawings but omit the rest. Respondents were asked to provide comments on needed changes to the presentation of design vehicles and related information in the Green Book. They commented as follows: • A generic turning template referring to the dimensions shown on a combined table would be a good approach to eliminate many template drawings. • Our agency requires the use of turning template software. • I think that they should be retained for all vehicles. This allows the designer to validate the paths that are being generated by the software package. • Retain current Green Book templates. Although our state uses turning template software, the information presented in the Green Book is helpful, provides history, provides useful dimensional criteria, provides valuable information on commonly used design vehicles, and supplements the information with text. Response Number (percent) of respondents AutoTURN 29 (82.9) Autodesk Vehicle Tracking (successor to AutoTRACK) 7 (20.0) Other (please specify) 1 (2.9) Table 12. Turning template software used by highway and transit agencies. Response Number (percent) of respondents 26 (74.3) 9 (25.7) TOTAL 35 (100.0) Show an example of one or two turning template drawings but omit the rest Retain turning template drawings for every design vehicle Table 13. Transportation agency assessment of potential changes in how turning templates are presented in the Green Book.

Survey of Transportation Agencies 29 • I believe the turning paths shown for each vehicle in the 2018 Green Book Figures 2-10 to 2-32 are good. Figures 9-23 to 9-30 from the 2011 Green Book are not needed because the intersections have varying widths and skew angles. Turning template software should be used for these intersections. • Some vehicle dimensions—including turning dimensions—should be retained for each design vehicle, but the type and amount of information should be reconsidered in light of computer-aided methods. For example, simply knowing the OTR for a vehicle can render dynamic modeling unnecessary in cases where only how far the vehicle swings out (and not the envelope) determines the design dimensions. The side views of each vehicle should be retained as is; they can be valuable for practitioners who are creating custom vehicles that are variations of standard vehicles. 3.2.13 Question 13—What Turning Radius Should Turning Templates in the Green Book Be Based On? Question 13 asked respondents what turning radius turning templates in the Green Book should be based on. Table 14 shows that 77% of respondents indicated that turning templates should be based on the minimum or tightest radius for the design vehicle, while 20% of respon- dents would prefer a slightly more generous radius (e.g., 10% higher than the minimum or tightest turning radius). These responses indicate that most agencies would prefer to see the minimum or tightest turning path so that they can make their own judgment on how much additional space should be provided. The respondent that indicated “other” provided the following comment: • Both minimum and a more generous design value are probably useful to present, much as we have minimum and desirable values for other design parameters. But to settle on a more generous design value, it would have to be some percentile or variance of observed turns in the real world, not some made-up number like 10% greater. 3.2.14 Question 14—Does Your Agency Have Computerized Records of Vehicle Classification Counts for Specific Locations from Continuous Count Stations, Weigh Stations, or Other Sources That Classify Truck Volumes by Truck Configuration? Question 14 asked respondents whether their agency has computerized records of vehicle classification counts for specific locations from continuous count stations, weigh stations, or other sources that classify truck volumes by truck configuration. Table 15 shows that 46% of respondents said that their agency has such records, 23% of respondents said that their agency does not have such records, and 31% of respondents said that they do not know whether their agency has such records. Comments from those agencies indicated a variety of data types available, Response Number (percent) of respondents Minimum or tightest turning radius for the design vehicle 27 (77.1) 7 (20.0) Other (please specify and/or provide any related comments) 1 (2.9) TOTAL 35 (100.0) A slightly more generous radius (e.g., 10% larger than the minimum or tightest turning radius) Table 14. Turning radius on which highway agencies indicate turning templates should be based.

30 Highway and Street Design Vehicles: An Update including classification counts by vehicle type or number of axles and weigh-in-motion data. A subsequent review found that such databases do not generally classify vehicle types in suf- ficient detail to be useful in this research. 3.2.15 Question 15—Does Your Agency Keep Tabulations of the Specific Truck Configurations for Which Oversize/Overweight Permits Are Issued Each Year? Question 15 asked respondents whether their agency keeps tabulations of the specific truck configurations for which oversize/overweight permits are issued each year. Table 16 shows that 26% of respondents said yes, 23% of respondents said no, and the rest of the respon- dents said that they did not know. Comments provided by the respondents that responded “YES” indicated that such tabulations are general and may not classify specific truck configu- rations exactly. Response Number (percent) of respondents Yes 16 (45.7) No 8 (22.9) Don’t know/No opinion 11 (31.4) TOTAL 35 (100.0) Table 15. Highway agencies with computerized records of vehicle classification counts. Response Number (percent) of respondents Yes 9 (25.7) No 8 (22.9) Don’t know/No opinion 18 (51.4) TOTAL 35 (100.0) Table 16. Highway agencies with records of specific truck configurations for oversize/overweight permits.

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Highway and Street Design Vehicles: An Update Get This Book
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 Highway and Street Design Vehicles: An Update
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Approximately 55 percent of the passenger vehicles registered in the United States are light trucks, such as sport utility vehicles, vans, minivans, and pickup trucks. Conventional automobiles, such as sedans and coupes, make up the rest of passenger vehicles.

NCHRP Research Report 1061: Highway and Street Design Vehicles: An Update, from TRB's National Cooperative Highway Research Program, proposes revisions to the dimensions of 16 of the 20 design vehicles used in the 2018 edition of AASHTO’s A Policy on Geometric Design of Highways and Streets, commonly known as the Green Book.

Supplemental to the report is a spreadsheet tool.

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