Practices for Operational Traffic Simulation Models (2025)
Chapter: Appendix A: Survey Questionnaire
APPENDIX A
Survey Questionnaire
NCHRP SYNTHESIS 20-05, TOPIC 55-13
PRACTICES FOR OPERATIONAL TRAFFIC SIMULATION MODELS
SURVEY
LETTER TO THE RESPONDENT
Dear Participant,
The Transportation Research Board (TRB), through the National Cooperative Highway Research Program (NCHRP), under the sponsorship of the American Association of State Highway and Transportation Officials (AASHTO), and in cooperation with the Federal Highway Administration (FHWA) is managing preparation of a synthesis report on practices for operational traffic simulation models.
The objective of the synthesis is to review and document DOT practices regarding the use of operational traffic simulation models. To view the scope of this synthesis, please click this link.
The findings of this synthesis will assist state DOTs in identifying best practices for leveraging operational traffic simulation models for design, planning, and operations of transportation networks. Your cooperation in completing this survey will help to ensure the success of this synthesis project, even if your DOT does not use operational traffic simulation models. If your DOT does not use operational traffic simulation models, the survey consists of two short multiple-choice questions that will take an estimated five minutes to complete. If your DOT does use operational traffic simulation models, the survey includes 24 questions, and we estimate that the survey will take approximately 15 to 30 minutes to complete. DOT survey responses will be shown in the published synthesis report. However, the identity of survey respondents will remain anonymous.
You have been identified as the appropriate person at your DOT to complete this survey. The survey link that you received is unique for your DOT and can only be completed once. If it would be more appropriate for someone else at your DOT to take this survey, please forward the
email with the survey link to them or send their name and email address to Henry Brown. You may also collaborate with colleagues at your DOT to complete the survey by sharing the survey link with them. The survey can be completed in multiple browser sessions. However, the survey may only be open on one computer at a time, and partial responses are saved upon closing the browser window. Consultation among DOT staff is encouraged, but we can only allow one response per DOT.
Additional instructions are provided at the beginning of the survey. If you would like to download a PDF version of the survey for informational purposes, please click here.
Please complete this survey by February 23, 2024. If you have any questions, please contact the Principal Investigator, Henry Brown. Any supporting materials may be sent by email to Henry or uploaded in lieu of providing URLs. Thank you for participating in this survey!
SURVEY INSTRUCTIONS
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SURVEY TIPS
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DEFINITIONS
An operational traffic simulation model is a mathematical representation of a transportation system developed using computer software that simulates the movement of traffic over a user-defined transportation network and provides results through reports and animation. An operational simulation model is a tool used to facilitate the planning, design, and operations of transportation systems and may be macroscopic, mesoscopic, or microscopic.
Macroscopic simulation models represent a higher-level approach with large spatial and temporal resolutions that are used for applications suitable to a lower level of accuracy. They utilize the deterministic relationships of flow, speed, and density. They require less computational effort than microsimulation models but provide less detail than microscopic models.
Mesoscopic simulation models represent transportation systems with a higher level of resolution than macroscopic simulation models but with less fidelity for driver behavior and vehicle interactions than microscopic simulation models. While mesoscopic simulation models are based on individual vehicles, the movement of vehicles is based on the principles of macroscopic models and average link speeds.
Microscopic simulation models mimic the movements of individual vehicles through a transportation network and track vehicle-to-vehicle interactions. Vehicles enter the transportation network through a stochastic process, are tracked in small units of time, and are given a destination, vehicle type, and driver type. Microsimulation models are used for detailed analyses with a smaller geographic footprint. They often require more modeling effort than other types of operational simulation models to provide a higher level of detail.
Multiresolution simulation modeling is an integrated approach that uses varying temporal and spatial resolutions (i.e., macroscopic, mesoscopic, and microscopic simulation) to answer a given question.
EXAMPLES
Example software tools used for operational traffic simulation models include the following:
- Aimsun
- CORSIM
- DTALite
- DYNASMART-P
- OPT/FREQ
- Quadstone Paramics
- SimTraffic
- SUMO
- TransModeler
- VISSIM
QUESTIONS
Contact Information
Name ___________________
State ___________________
Job Title ___________________
Phone Number _____________________
Email Address ______________________
- Does your DOT use operational traffic simulation models?
Yes (Continue to Question No. 2) No (Skip to Question No. 25) - For approximately how many projects does your DOT use operational traffic simulation models each year?
0 to 10 11 to 25 26 to 50 51 to 100 More than 100
- For approximately what percentage of projects does your DOT use operational traffic simulation models?
___________
(Implemented as slider (0% to 100%) in 5 percent increments.)
- Approximately what percentage of the operational traffic simulation models for your DOT are developed by consultants?
0% (all operational traffic simulation models are developed in-house) 1% to 25% 26% to 50% 51% to 75% 76% to 99% 100% (all operational traffic simulation models are developed by consultants)
- For which of the following applications does your DOT use operational traffic simulation models to some extent? Please select all that apply.
Freeway design alternatives analyses Arterial design alternative analyses Mixed design alternative analyses Signal retiming analyses
-
ITS implementation alternative analyses Traffic impact analyses (TIAs) Evacuation route analyses Work zone analyses Design visualization and communication Other (Please describe) _____
- Based on your response to the previous question, a list of applications for operational traffic simulation models used by your DOT is shown below. How frequently does your DOT use operational traffic simulation models for each of the following applications? (Only display applications selected in Question No. 5.)
Application Always Usually Sometimes Rarely Freeway design alternatives analyses Arterial design alternative analyses Mixed design alternative analyses Signal retiming analyses ITS implementation alternative analyses Traffic impact analyses (TIAs) Evacuation route analyses Work zone analyses Design visualization and communication Other - For which of the following specialized applications does your DOT use operational traffic simulation models? Please select all that apply.
Hybrid/Multi-resolution modeling Dynamic traffic assignment
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TSMO operational analysis (managed lanes, variable speed limits, etc.) Signal optimization Reliability analyses Connected/automated vehicle analyses Other (Please describe) _____
- Please rank the following simulation modeling resolutions based on the frequency of use by your DOT (1 = simulation modeling resolution associated with highest frequency of use, 2 = simulation modeling resolution associated with second highest frequency of use, etc.). If your DOT does not use a given simulation modeling resolution, please leave that entry blank.
Simulation Modeling Resolution Rank Macroscopic Mesoscopic Microscopic Multi-resolution - Which of the following types of software for operational traffic simulation models does your DOT use? Please select all that apply.
Aimsun CORSIM DTALite DYNASMART-P OPT/FREQ Quadstone Paramics SimTraffic SUMO TransModeler VISSIM Other (Please describe) _____
- A list of factors related to operational traffic simulation modeling is shown below. Please rank the top three factors based on their importance to your DOT’s processes for operational traffic simulation modeling (1 = most important, 2 = second most important, 3 = third most important). (Validation to ensure they rank at most three.)
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Factor Ranking Justifying Need for Simulation Analysis Data Availability Level of Modeling Effort Budget Constraints Scheduling Constraints Model Size (Simulation Geographic Extent) Simulation Duration (Simulation Temporal Extent) Multimodal Considerations Calibrating to Travel Conditions Future Year Analyses Other (Please describe) _____ - How frequently does your DOT use each of the following data sources for operational traffic simulation models?
Data Source Always Usually Sometimes Rarely Never Aerial Imagery As-Built Plans GIS Data (e.g., Speed Limits) Online Map Data (e.g., Google Maps) Drone Footage Field Observations
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Bluetooth Speed Data Manual Travel Time Runs Probe Travel Time or Speed Data Queuing Data Speed Studies Traffic Counts Output from Regional Travel Demand Forecasting Models Probe O-D Data Transit Data Other (Please describe) _____ - What guidelines does your DOT most frequently follow to calibrate simulation models?
Traffic Analysis Toolbox Volume III: Guidelines for Applying Traffic Microsimulation Software (FHWA 2004) TAT Volume III: Guidelines for Applying Traffic Microsimulation Modeling Software 2019 Update to the 2004 Version (FHWA 2019) State-specific guidance Ad hoc project-based decisions as there is no state-specific guidance Other (Please describe) _____
- Does your DOT have a process for documenting deviations from modeling guidance on specific projects?
Yes No Not applicable, models developed by my DOT do not typically deviate from modeling guidance
-
Not applicable, there is no state-specific guidance regarding thresholds and acceptance of deviations
- How frequently does your DOT use each of the following calibration metrics?
Calibration Metric Always Usually Sometimes Rarely Never Travel Times Volumes Queue Length Freeway Density Intersection LOS Visual Inspection Other (Please describe) _____ - How frequently does your DOT incorporate the following processes for the review of operational traffic simulation models?
Process Always Usually Sometimes Rarely Never Completion of Model Review Checklist Use of Independent Reviewer Review of Animation Review of Model Error Log
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Review of Model Input Data Review of Performance Measures Reported from Model Other (Please describe) _____ - How frequently does your DOT use the following MOEs as output for operational traffic simulation models for facilities with uninterrupted flow (e.g., freeways)?
Measure of Effectiveness (MOE) Always Usually Sometimes Rarely Never Delay / Level of Service (LOS) Density / LOS Duration of Congestion Queue length Speed Travel Time Visualization of Results / Animation Volume Throughput Other (Please describe) _____ - How frequently does your DOT use the following MOEs as output for operational traffic simulation models for facilities with interrupted flow (e.g., arterials)?
-
Measure of Effectiveness (MOE) Always Usually Sometimes Rarely Never Delay / Level of Service (LOS) Density / LOS Duration of Congestion Queue length Speed Travel Time Visualization of Results / Animation Volume Throughput Other (Please describe) _____ - How frequently does your DOT reuse or adapt previously developed operational traffic simulation models for new projects requiring the use of operational traffic simulation models?
Always Usually Sometimes Rarely Never
- Approximately how frequently does your DOT adopt new versions of simulation software?
Every year Every two years Every three to five years Every six to ten years Every ten years or more My DOT does not adopt new versions of simulation software Other (Please describe) _____
- Which of the following deliverables for operational traffic simulation models does your DOT require? Please select all that apply.
Animation files Simulation model files Data archiving plan Calibration tables or memo Methods and assumptions document Summary of MOEs Quality control (QC) checklist Technical memorandum of results Volume diagrams Other (Please describe) _____
- Which of the following resources has your DOT developed to support the use of operational traffic simulation models? Please select all that apply.
Checklists Guidance documents Policies Procedures for maintenance and archiving of data Procedures for model development and review Procedures for model scoping Standards Suggested calibration parameters Thresholds for calibration acceptance Training materials Studies on benefits and/or return on investment for the use of operational traffic simulation models My DOT uses resources from other state DOTs (please describe and indicate which state DOTs) ____________ My DOT primarily uses resources from FHWA Other (Please describe) _____ None of the above
Based on your response to Question No. 21, a list of resource types for which your DOT has developed resources is shown below. Please provide URL(s) for your DOT’s resources for each of these resource types in the boxes below, upload files, or email files. (Only display question if any resource types are selected in Question No. 21. For list of answers, only display resource types selected in Question No. 21.)
Checklists (_________)
Guidance documents (_________)
Policies (_________)
Procedures for maintenance and archiving of data (_________)
Procedures for model development and review (_________)
Procedures for model scoping (_________)
Standards (_________)
Suggested calibration parameters (_________)
Thresholds for calibration acceptance (_________)
Training materials (_________)
Studies on benefits and/or return on investment for the use of operational traffic simulation
models (_________)
My DOT uses resources from other state DOTs (_________)
My DOT primarily uses resources from FHWA (_________)
Other (_________)
- In what divisions of your DOT are the internal staff for the development and/or review of operational traffic simulation models placed? Please select all that apply.
Design Operations Planning Program Delivery Other (Please describe) _____ My DOT does not have internal staff for the development and/or review of operational traffic simulation models
- Which of the following statements regarding your DOT’s practices for the use of operational traffic simulation models is true? Please select all that apply.
My DOT requires approval for the use of operational traffic simulation models on each project My DOT most frequently uses operational traffic simulation models for freeways My DOT fuses data from different sources for operational traffic simulation models My DOT updates data inputs for operational traffic simulation models on a regular basis My DOT requires all simulation results to be reported with a minimum of 10 simulation seeds My agency places emphasis on different model parameters based on the modeling software being used or type of application My DOT sometimes performs post-construction verification of operational traffic simulation models My DOT provides training on the use of operational traffic simulation models (e.g., policies and procedures, software)
-
My DOT spends a lot of resources on researching and updating our state-specific guidance None of the above
- The synthesis study will also include case examples demonstrating DOT practices for operational traffic simulation models. The development of the case examples will require an additional follow-up interview (to be conducted virtually). DOTs participating in the case examples will be provided with an opportunity to review the case example write-up for accuracy. The names of interviewees will be anonymous. Agencies participating in the case examples will be provided with an opportunity to review the case example write-up. The estimated time commitment for your DOT for the case example is 1 to 1.5 hours for the followup interview and 1 hour to review the write-up. Would your DOT be interested in participating in a case example?
Yes No
Please suggest project ideas for case examples using the box below: (Only display if answer to Question No. 24 = “Yes.”)
- To your knowledge, is your DOT considering the use of operational traffic simulation models in the future? (Only display if answer to Question No. 1 = “No.”)
Yes Not at this time No, my DOT focuses on the use of other tools (please briefly describe other tools) ____________ Other (please describe) ____________
SUBMITTAL INSTRUCTIONS
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Please note that once you click the “Submit” button, you will not be able to modify your answers. To save your partial answers and complete the survey later, close the survey. Answers are automatically saved upon closing the browser window. To return to the survey later, open the original email from Henry Brown and click on the survey link. To pass a partially completed survey to a colleague, close the survey and forward the original email from Henry Brown to a colleague. Note that only one person may work on the survey at a time; the survey response should only be active on one computer at a time. To review your answers before submitting, please select the forward and back arrows at the bottom of each page.
END OF SURVEY
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Henry Brown, P.E.
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