Roadside Safety Analysis Program (RSAP) Update (2022)

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8 Highway Safety Manual The development of the Highway Safety Manual is both the synthesis and culmination of the crash-data based approach to highway and roadside safety [AASHTO10]. Development of the HSM was initiated by a Transportation Research Task Force and, so far, supported by six NCHRP projects totaling more than $3 million with additional projects still being planned. The HSM focuses on knowledge and tools relevant to the safety profession and will quantify the safety effects of decisions in planning, design, operations, and maintenance. It is intended to serve a role for safety analysis similar to that which the Highway Capacity Manual (HCM) serves for traffic operational analysis. The HSM attempts to predict all types of crashes for highway segments and intersections. NCHRP Project 17-54, “Consideration of Roadside Features in the Highway Safety Manual,” is ongoing.[Ray14] That project will develop statistical regression models based on police-level reported crashes with accompanying crash modification factors for roadside features. These new models are anticipated to be used for area-wide assessment while RSAPv3 should be the tool used for the assessment of roadside alternatives during detailed design and for policy development. APPROPRIATE USE OF ANALYSIS APPROACHES It is not an easy matter to compare the predictions from an encroachment-based method (i.e., RSAPv3) with those from a crash-data based method (i.e., the HSM) for several reasons. These two different approaches use different techniques to estimate the frequency of crashes. The crash-data based approach is in essence a macro approach where an estimate is developed based on a broad and general overview of the highway characteristics. The encroachment approach, on the other hand, is a micro approach where the detailed interactions of each roadside feature are accounted for. In the end, both approaches ought to produce compatible measures of crash frequency and crash severity but it should be recognized that they are approaching the problem from fundamentally different perspectives. NCHRP 17-54 is currently developing roadside predictive procedures for the HSM.[Ray14] That project will ensure the compatibility of the results obtained from each approach. Upon completion on NCHRP 17-54, those predictive procedures should be used for broad scale analysis of roadside improvement alternatives whereas RSAPv3 should be used for the analysis of design alternatives for specific projects and the development of roadside design policy. RESULTS OF SURVEY OF PRACTICE A survey was conducted to ask users of the prior versions of RSAP to identify and catalog problems and perceived shortcomings of RSAP. The survey was distributed via e-mail to about 2,100 roadside safety researchers, highway design consultants, DOT engineers, and users of highway design software. The distribution list was compiled from the ITE database, ATSSA training course participants, members of TRB AFB20 and AASHTO-ARTBA-AGC TF13 and from a list of people who have purchased the Roadside Design Guide from AASHTO. A complete copy of the questionnaire can be found in Appendix B. The survey was assembled using the online tool surveymonkey.com (i.e., www.surveymonkey.com). The survey had several purposes including: 1. To identify the user community of the existing RSAP program. 2. To determine the degree to which RSAP is used in the design profession.

9 3. To identify known RSAP software “bugs” and limitations that may lead to misguided results or present users with results that are difficult to interpret. 4. To solicit the types of software highway designers are using for their particular highway design projects. Approximately 136 people started the survey and 122 people completed it resulting in a completion rate of 84 percent. The remaining 1900 or so that did not respond in any way are presumed to know nothing about RSAP or are not active in the roadside safety aspects of highway design. The survey asked a variety of questions about the type of work the respondent does the software tools they use their use of RSAP, specific questions about RSAP and solicited beta testers for the updated RSAP. The following sections discuss each question and describe the research team’s assessment of the responses. Question 1: Please provide the following optional information about yourself. Respondents were asked to provide contact information. Approximately 85 percent of the respondents provided this information. Question 2: What type of work do you do? Most of the respondents consider themselves roadside and/or highway designers, as shown in Figure 1. The respondents who describe themselves as doing “other” work are engaged in activities like the manufacturing or distribution roadside devices, performing structural or traffic design services, constructing highway improvements and/or participating in engineering education. Respondents could check all categories which define the work they do, therefore, somebody who engages in highway design production and research would have checked both categories and been counted twice. One interesting observation is that most respondents engage in some type of design work with 60 percent identifying themselves as working as roadside designers and more than 50 percent working as highway designers. Policy work, roadside safety research and highway design research were identified in about 20 percent of the responses as shown in Figure 1.

10 Figure 1. Distribution of Respondents’ Work Categories. Question 3: Which highway design software tools does your company/organization use for design and plan production? 86 percent of the respondents use some form of CAD-based software tools for documentation and plan production as shown in Figure 2. Given the wide range of survey distribution, this is a staggering number. Respondents also noted the use of several other Bentley and Autodesk products or add-on products, which serve specific design functions, such as designing signs, hydraulic systems, or vehicle turning paths. DeSantis Engineering software was also mentioned by several respondents. Almost 30 percent of respondents use Autodesk’s Civil3D, 13 percent uses Autodesk Land Development Desktop, and another 30 percent use Bentley’s InRoads software. All three of these highway design programs are built on the AutoCAD platform, which means approximately 73 percent of the respondents are working with design software running through the AutoCAD API. It is not uncommon for large consultant firms to produce plans for different jobs in different CAD programs to meet the requirements of a State DOT or private client. Therefore, it’s expected that many of the larger firms who responded opted to check more than one design software.

11 Figure 2. Distribution of CAD Software Use. Question 4: Please list other software tools you use to assist with design decisions and cost analysis. Survey respondents indicated they use a surprisingly small variety of additional software to support design decisions and cost analysis. This software, in addition to RSAP, primarily includes traffic analysis software, spreadsheets and GIS applications. This would indicate that there is little standardization across the highway design industry for cost analysis procedures and protocol but there is great potential for an easy-to-use and effective benefit-cost program. Question 5: The Roadside Safety Analysis Program (RSAP) has been developed for risk analysis and cost-benefit analysis of roadside safety and design. It is distributed with the Roadside Design Guide. How frequently do you use RSAP? The responses to this question indicate that RSAP is not used as often as it could be. 65 percent of the respondents do not use RSAP at all while 26 percent use RSAP one to five times per year. Designing improvements to the roadside can be challenging, especially in an environment where funds are limited. A tool such as RSAP could provide valuable insight to help a project designer, but RSAP appears to be underused as shown in Figure 20. Understanding why RSAP is underused will help improve use statistics and project designs. This probably indicates that RSAP is largely used as a policy tool rather than for specific project decisions. Question 6: What have you used RSAP to evaluate? A majority of the respondents, who have used RSAP, have used it to evaluate specific design alternatives (i.e., 77 percent). A smaller percentage of the total respondents (40 percent) have used RSAP to evaluate policy alternatives, which could be a reflection of the number of policies made as compared to the number of designs prepared. Others note the use of RSAP in

12 research and teaching applications alternatives (i.e., 23 percent). These results are encouraging for improving roadside designs, but more widespread use is needed, as discussed above. Question 7: Do you like the RSAP user interface? While 60 percent of the respondents said they like the user interface, a number of comments were received about improving the data entry methods. Some suggestions included improving the highway geometrics data entry time through a more graphically based user interface. It appears that respondents would be in favor of maintaining the windows-based user interface while adding a graphical component to ease highway design data entry. A few quotes from the survey are presented here: • “Time consuming to enter in data and make sure that the data is correct.” • “Needs a graphical interface.” • “Visual representation of model – graphics.” Question 8: Do you like RSAP functionalities? 77 percent of the respondents like the RSAP functionalities, however, many suggested improvements. These suggested improvements again include mention of a graphical interface for data entry of the highway elements. Additional improvements suggested include referencing a project baseline for measurements rather than “distance from beginning” and more flexibility with the default features. Again, the concern about entering highway elements through a graphically based environment was noted and should be addressed in the updated version of RSAP. A select number of specific suggestions are presented here: • “Making the functionalities more specific, with more availability to detail situations and have a more accurate model of the alternatives you are trying to evaluate.” • “Because it is difficult to input data it is hard to check and make sure that this is correct, Some type of graphical interface for cross section data would be appreciated.” • “The program should be redesigned to work around the standard industry practice for building roads that uses a control line of stationing to define the longitudinal location of features. All of our data is based on this method including profile grades, locations of features, survey data, right-of-way, etc. The RSAP currently requires us to build a spreadsheet that correlates all of the data we gather using the control line method to the "distance from beginning of project" method used by the programmer. It is the most important thing that needs to be changed in order for this product to be accepted by the industry.” • “Continuous slope hazards, contingent on trajectory dependence rather than fixed- location hazard envelopes, would be desirable. Example: some severity is present for a 2 ft lateral encroachment on a 2:1 slope, a higher severity is present for a 10 ft encroachment, and a higher severity for a 30 ft encroachment etc. It should be both longitudinally and laterally-dependent for severity estimation.” • “A multiple-run option should be included to allow users to name the parameters to be updated and multiple analyses conducted without intensive user input. Reducing the effort required to run multiple jobs will save time and money in the evaluation, and will reduce the number of user-caused errors in the evaluations.”

13 Question 9: Do you find the RSAP default data tables appropriate? 70 percent of the respondents agree that the default data tables are appropriate. Comments received and suggestions for improvements include concerns over the age of the crash costs and the appropriateness of the severity indices. Specifically culvert grates and trees were mentioned for consideration and investigation of severity. Also suggestions where received to improve documentation abilities by allowing the user to print default data table choices as part of the report summary. Comments received indicate that improving the user’s ability to interface with the data tables and update the default data will improve the user-friendliness of this program and help keep the program up-to-date between whole version updates. A selected sample of survey quotes are presented here: • “Need to be updated with current data - costs, vehicle trajectories, damages.” • “You need to include a means for printing them out. They are critical to the cost/benefit analysis but there is no way of easily including them in a final report so managers and posterity have the details of what the decisions are based on. Plus, we use the severity index tables for other purposes and the only way we can refer to them is in an out-dated edition of the RDG.” • “Modeled severities of vertical drops are incorrect. Slope drop-off severities should be the same for the same height of drop-off for both intersecting slopes and fore-slopes.” • “Rigid-object sizes are very large; there should be some smaller rigid-object size classifications.” • “Culvert grates ought to be investigated as an additional hazard class.” • “The Severity Indices are incomplete and what is there needs updating.” • “Crash costs should reflect more recent data.” Question 10: Do you like the RSAP methodology? General responses to this question include requests for better documentation within the software and the manuals to allow users to explain and compare the results. 80 percent of the respondents agree with the choice of RSAP methodology, however, some feel the encroachment data is weak and would prefer a different methodology which does not rely on this data. Specific suggestions were made to incorporate a scaling effect, based on yaw degree, for side impact to increase the severity of those crashes and possibility incorporate a secondary trajectory algorithm to account for vehicles which may slide along a roadside feature such as guardrail. Respondents generally agree with the methodology, but would like to see updated encroachment data and the possibility of more modification factors incorporated into the updated version of RSAP. Specific suggestions are presented here: • “Incorporation of scaling effects based yaw degree from impact should be incorporated. For example, scale severities of rigid objects when impacted in the side by a factor of 1.5; this may over represent the severity of side-impact crashes, but it will lead to possibly more accurate severity indices for most other object types through in-service evaluations and validation rather than a fixed severity regardless of yaw angle.” • “The encroachment data is a very weak link in the chain. Given this fundamental weakness, I would prefer a program that is probabilistic-oriented, as opposed to the current deterministic style.” • “Cannot get realistic output.”

14 Question 11: Do you find the RSAP User's Manual helpful? Most people responding do find the User’s Manual helpful (72 percent). Specific comments for improving the User’s Manual include incorporating more discussion on the limitations of RSAP and discussion about the different computational steps of the program. Suggestions for graphical representations of measurements to ensure properly entering data into RSAP were also made. Concerns about difficulty of data entry persist. Question 12: Do you find the Engineer's Manual helpful? While 80 percent of the respondents found the Engineer’s Manual helpful, several respondents were not even aware there was an Engineer’s Manual. Some respondents suggested that improvements should be made to clarify the distinction between ditches and foreslope/backslope combinations and the use of RSAP in median evaluations. Generally, there was concern about the documentation and improvements should be made. Specific suggestions are presented here: • “Only marginally helpful.” • “I'm not sure when it is ok to use foreslope and backslopes verses ‘parallel ditches.’” • “When should/ how should a person decide to use ‘user defined features.’” • “Add discussion on the use of RSAP for median applications for divided highway.” • “Not enough detail.” Question 13: While using RSAP, have you encountered any incidents where your analysis results from RSAP were inconsistent with your experience/expectations/judgment? Concerns were expressed over the precision of the reported numbers, given the amount of engineering judgment the program is founded upon. Some of specific incidents identified are as follows: • “Analyzing bridge rails with different shoulder widths gives the rail with the narrowest shoulder as the lowest user cost because the narrow shoulder presumably does not allow a higher impact angle. Intuitively, a wider shoulder should be better.” • “RDG indicates 4:1 to 4:1 ditches are not desirable. I would guess that RSAP would have a larger SI.” • “Whenever the user attempts to run a one way one lane roadway an error message occurs that states “Unexpected Termination of Analysis Module.” This makes it impossible to run one lane ramps.” • “Problems have been reported when attempting to run user defined features. When a user inputs small increases to the severity values at 100 km/hour, sometimes the output does not show increases in average severity or annual crash cost.” • “When crash costs are changed from User Defined Costs- KABCO to the Roadside Design Guide’s values, the annual crash cost does not change significantly.” • “In order to enter English units the user must use the pull down menu under view- options, then change into metric units and back to English units. If the user does not do this step, the input screens will request input in feet and require the user to use metric values. Even though the input is in metric units, the output is in English units.” • “The rigid-object hazards were at times less severe than guardrail.”

15 • “A bridge requires extensive coding increments of the drop-offs adjacent to the bridge, since otherwise the bridge drop-offs are not accurately modeled. Placement of the slope immediately next to the bridge results in an odd recommendation. Slopes in general are difficult since they are often large rectangular hazards with constant severity, though this is not physically observed in the field.” • “Flat ground "severity" should be automatically incorporated into the model everywhere that there is no other hazard.” • “There are inconsistencies between RSAP and the HSM.” These quotes illustrate that there are perceived issues with the severity coding, the units coding and precision of answers. It appears that frequent users have found some “work-arounds” for some problems but the appropriateness or correctness of these techniques is unknown. Question 14: Are you aware of reports or papers about RSAP documenting its use? Please list them here. Respondents suggested that many reports are currently being developed, but none were listed or provided. Question 15: What improvements would you like to see made to RSAP? The improvements suggested can be separated into five general categories including RSAP’s reporting features, user interface, documentation, methodology, default data, and items the respondents would like to see added to RSAP. Suggested improvements to RSAP reports include adding the ability to produce PDFs and reporting the information in a more concise manner. Additionally, the ability to report and print the severity index table and the costs for fatal and injury crashes would be helpful. Many respondents suggested the user interface could be improved by adding a means to graphically input cross-sectional and roadway information. Respondents suggested improving the software’s internal and external documentation with example diagrams and pictures to help define data entry measurements and terms as well as more comprehensive manuals would help reduce user input error. Respondents suggested updating the default roadside features to include a range of cable barrier, among other recent changes, to the roadside inventories. Additionally, integration of length of need calculations into RSAP would help designers. Furthermore, it was suggested that construction costs for roadside features could be added to the program. Regarding the methodology, suggestions were made to include more user adjustment factors and better document the use of the adjustment factor. Updates should be made to the algorithms used to calculate the trajectory (a cubic function, for example) and yaw-related severity scaling and what some respondents view as methodology weaknesses should be addressed in this update (i.e., S.I. and encroachment rates). Question 16: Which features of RSAP would you like to see remain unchanged in the next release? There is some interest among respondents in retaining the windows-style user interface, the use of the Cooper data, the ability to customize crash values, and RSAP’s name.

16 Question 17: Do you see value in integrating RSAP with popular highway design software tools such as AutoCAD Civil3D or Bentley InRoads? Eight-5 percent of the respondents agree that integrating RSAP with design tools like AutoCAD Civil3D and Bentley InRoads would add value but there is also a strong desire to maintain the current ability to run RSAP independent of CAD-based software. Question 18: Do you see a potential use for evaluating the Cost/Benefit of roadside design alternatives using software integrated with your highway design software? 78 percent of the respondents do see a potential use for evaluating the cost/benefit of roadside design alternatives. Some feel it needs to be a simple tool and some are not sure how it will apply across all roadway design scenarios. Question 19: Do you believe safety, or the potential for crashes should be considered when designing highway improvements? One-hundred percent of respondents believe safety should be considered when designing highway improvements. Respondents noted a need for tools and processes that explicitly include safety consequences, to assist designs in making decisions. Respondents also noted that safety should be considered but not required. Question 20: Thank you for your time. If you would like to be a beta tester for the RSAP upgrade, please list your contact information, including your e-mail, here. Twenty-four people were identified as beta testers including some panel members, state engineers, highway consultants, researchers, and software developers. Conclusions Most of the respondents use some type of CAD-based highway design software to assist in the production of the highway designs, however, only 35 percent of the respondents use or have used RSAP. Of the RSAP user population, approximately 75 percent have used it to assess specific design alternatives. Therefore, it’s probably no surprise that approximately 80 percent of respondents see value in integrating RSAP with highway design software such as Civil3D or InRoads but many would like to maintain the ability to manually input data and run RSAP independently. General respondent comments include a preference to maintain the current windows user interface, however, many respondents suggested a more visual or graphical representation of the project to improve clarity. Integration of RSAP with Civil3D or InRoads would address respondents concerns over creating a graphic interface for highway element data entry. Respondents suggested improving the ability to change or edit default values as well as more flexibility when entering roadside features. Allowing for easy user updates of RSAP will grant users more flexibility and keep RSAP more up-to-date at a national level as well as relevant at a regional level. Perhaps most significant, however, is that the RSAP user community appears to be quite small. While this might be looked at as discouraging news it can also be viewed as a place of great potential. There is apparently demand for an updated RSAP that provides a significantly increased value to roadside designers as there is certainly nothing else in the marketplace that is competing with RSAP.