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Traffic Assignment and Feedback Research to Support Improved Travel Forecasting PDF

328 Pages·2015·17.76 MB·English
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Traffic Assignment and Feedback Research to Support Improved Travel Forecasting Prepared for: Federal Transit Administration Office of Planning and Environment Under Contract No. DTFT60-11-D-00009 Prepared by: Caliper Corporation Cover photos: “Link and I-5 southbound from S 144th Street” by SounderBruce / CC BY 2.0 “Dallas_Exterior_2086” by Kinkisharyo / CC BY 2.0 “Future City” by Neil Kremer / CC BY 2.0 “Seattle Trolley Bus” by Oran Viriyinci / CC BY 2.0 “Phoenix Traffic Assignment” and “Intersection Simulation” courtesy of Caliper Corporation Traffic Assignment and Feedback Research to Support Improved Travel Forecasting FINAL REPORT Prepared for: Federal Transit Administration Office of Planning and Environment Under Contract No. DTFT60-11-D-00009 Prepared by Caliper Corporation 1172 Beacon St Newton, MA 02461 www.caliper.com July 31, 2015 DISCLAIMER NOTICE This document is disseminated under the sponsorship of the United States Department of Transportation (USDOT) in the interest of information exchange. The United States Government assumes no liability for its contents or use thereof. The United States Government does not endorse products of manufacturers. Trademarks or manufacturers’ names appear in the document only because they are essential to the objective of this report. The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the USDOT or of the Metropolitan Planning Organizations that participated in the research. Form Approved REPORT DOCUMENTATION PAGE OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202- 4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 2. REPORT TYPE 3. DATES COVERED (From - To) 31-07-2015 Final Report 23-09-2011 to 31-07-2015 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER DTFT60-11-D-00009 T raffic Assignment and Feedback Research to Support Improved Travel Forecasting 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Howard Slavin, Jim Lam, and Kanchana Nanduri 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT C aliper Corporation 1172 Beacon St., Suite 300 Newton, MA 02461 9. SPONSORING / MONITORING AGENCY N AME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S Federal Transit Administration ACRONYM(S) O ffice of Planning & Environment Analysis Division, TPE-22 1200 New Jersey Avenue, SE Washington, D.C. 20590 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 12. DISTRIBUTION / AVAILABILITY STATEMENT 1 3. SUPPLEMENTARY NOTES 14. ABSTRACT This research investigated whether or not current traffic assignment and model feedback practices are sufficiently accurate for calculating congested highway travel times and for quantifying the highway benefits of major transit projects. Examination of U.S. MPO modeling practices indicated widespread deficiencies in implementation. Empirical investigation of assignment and feedback convergence errors present in some of the better MPO models indicated that with available methodological improvements and more extensive computation, existing methods could produce plausible estimates of highway and transit project impacts. Comparisons between modeled and measured congested travel times from commercial sources indicated that models tended to underestimate travel speeds, and that use of speed data would be beneficial in model calibration and validation. 15. SUBJECT TERMS Traffic assignment, user equilibrium, travel time measurement, demand model calibration and validation, speed feedback, model convergence 16. SECURITY CLASSIFICATION OF: 17. LIMITATION 18. NUMBER 19a. NAME OF RESPONSIBLE OF ABSTRACT OF PAGES PERSON a. REPORT b. ABSTRACT c. THIS PAGE 1 9b. TELEPHONE NUMBER Unclassified Unclassified Unclassified 314 (include area code) Standard Form 298 (Rev. 8- 98) Table of Contents Chapter 1 Introduction and Executive Summary ............................... 1-1 Study Approach ........................................................................................................................1 -2 Inventory of MPO Modeling Practices ...................................................................................... 1-3 MPO traffic assignment practices ....................................................................................... 1-3 MPO feedback practices .................................................................................................... 1-3 Detailed Examination of Selected MPO models ....................................................................... 1-4 An Overview of the 5 MPO Models .......................................................................................... 1-4 Network geography and attributes ...................................................................................... 1-5 Volume-delay functions ...................................................................................................... 1-5 Assignment methods and convergence ............................................................................. 1-5 Traffic Assignment Investigations and Findings ....................................................................... 1-5 Validation of models with traffic counts .............................................................................. 1-6 Feedback Research and Findings ............................................................................................ 1-7 Project Impact Analysis ............................................................................................................1 -7 Congested Travel Times from MPO Models ............................................................................ 1-8 Summary Conclusions and Recommendations ........................................................................ 1-9 Recommendations for FTA guidance ............................................................................... 1-10 Research recommendations ............................................................................................. 1-11 Concluding remarks ..........................................................................................................1 -11 Chapter 2: Inventory of MPO Traffic Assignment Modeling Practices ............................................................................................ 2-1 Introduction ...............................................................................................................................2 -1 Background on Equilibrium Traffic Assignment Models and Convergence .............................. 2-2 Current MPO Traffic Assignment Procedures ........................................................................ 2-13 Concluding Remarks ..............................................................................................................2 -15 Chapter 3 Current Practices in Computing Model Feedback ............ 3-1 Background on Feedback Convergence .................................................................................. 3-1 Feedback Methods in Use ........................................................................................................3 -5 Concluding Remarks ................................................................................................................3 -7 Chapter 4: Overview of the ARC, MAG, NCTCOG, PSRC, and SANDAG Models ............................................................................... 4-1 Model Information Summary Tables ......................................................................................... 4-2 MPO Model Formulations .........................................................................................................4 -8 Trip purposes ......................................................................................................................4 -8 Travel modes ......................................................................................................................4 -9 Traffic Assignment Problem Characteristics ............................................................................. 4-9 Network size & software ..................................................................................................... 4-9 Geographic network representation ................................................................................. 4-10 Turn prohibitions and penalties ........................................................................................ 4-10 Centroid connectors .........................................................................................................4 -12 Area types ........................................................................................................................4 -16 AM trip characteristics ...................................................................................................... 4-20 Capacities .........................................................................................................................4 -25 PCEs for vehicle classes .................................................................................................. 4-26 Transit preloads ................................................................................................................4 -26 Assignment generalized cost impedance functions .......................................................... 4-26 Values of time ...................................................................................................................4 -26 Volume-delay functions .................................................................................................... 4-27 MPO Base Model Traffic Assignments ................................................................................... 4-34 Trip speeds .......................................................................................................................4 -35 Concluding Remarks ..............................................................................................................4 -39 Chapter 5 Traffic Assignment Models and Tests ................................ 5-1 Traffic Assignment Runs ..........................................................................................................5 -2 Volume-to-capacity ratios ................................................................................................... 5-4 Zero flow link analysis ........................................................................................................5 -7 Convergence Error Analysis ..................................................................................................... 5-9 Comparison of Assignment Volumes and Traffic Counts ....................................................... 5-14 ARC flows and counts ...................................................................................................... 5-15 MAG flows and counts ...................................................................................................... 5-17 NCTCOG flow versus count comparison .......................................................................... 5-20 PSRC flow versus count comparison ............................................................................... 5-23 SANDAG flow versus count comparisons ........................................................................ 5-24 Validation of multi-class assignments ............................................................................... 5-32 Other Traffic Assignment Investigations ................................................................................. 5-33 Analysis of operating costs in traffic assignment impedance ........................................... 5-33 PSRC trip rounding analysis ............................................................................................. 5-38 Conclusions ............................................................................................................................5 -41 Chapter 6 Feedback Methods and Convergence Tests ...................... 6-1 Overview of the 5 MPO Model Feedback Approaches ............................................................. 6-1 Closure metrics and tolerances .......................................................................................... 6-3 Initial speeds .......................................................................................................................6 -3 Bus speeds .........................................................................................................................6 -3 Appropriateness of feedback closure metrics ..................................................................... 6-4 Feedback Runs ........................................................................................................................6 -5 Feedback runs with the MAG model .................................................................................. 6-6 NCTCOG model feedback runs ........................................................................................ 6-12 Feedback in the PSRC model .......................................................................................... 6-20 Feedback runs with SANDAG activity-based model ......................................................... 6-20 Conclusions ............................................................................................................................6 -26 Chapter 7 Project Impact Analysis ....................................................... 7-1 Impact of a Roadway Project in Atlanta .................................................................................... 7-2 Impact of a Roadway Project in Phoenix .................................................................................. 7-7 MAG mode choice and assignment with highway project added ..................................... 7-11 MAG single loop run with highway project added ............................................................. 7-13 MAG full model run with highway project added............................................................... 7-16 Impact of a Transit Improvement Project in Phoenix .............................................................. 7-19 MAG mode choice and assignment with transit project added ......................................... 7-20 Transit project impacts assessed with a MAG full model run ........................................... 7-25 Impact of a Roadway Project in Dallas-Ft. Worth ................................................................... 7-31 NCTCOG AM highway assignment-only results with highway project added .................. 7-32 Added lanes assessed with the NCTCOG mode choice and assignment models ........... 7-34 Lane expansion evaluated with a full NCTCOG model run .............................................. 7-37 Impact of a Light Rail Extension in Dallas-Ft. Worth .............................................................. 7-41 Light rail extension impact with the NCTCOG mode choice and assignment models ...... 7-43 Light rail extension impact assessed with an NCTCOG full model run ............................ 7-47 Impact of a Roadway Project in the Puget Sound region ....................................................... 7-54 Impact of a widened arterial in the PSRC region .............................................................. 7-54 PSRC full model run with highway project added ............................................................. 7-60 Impact of a Roadway Project in San Diego ............................................................................ 7-63 Assignment-only analysis ................................................................................................. 7-64 Impacts assessed with a single model loop...................................................................... 7-68 SANDAG full model run with highway project added ....................................................... 7-70 Impact of a Transit Project in San Diego ................................................................................ 7-74 Transit project impacts with a SANDAG single loop model run ........................................ 7-75 Transit project impacts from a full SANDAG model run .................................................... 7-79 Conclusions ............................................................................................................................7 -85 Chapter 8 Congested Travel Time Analysis ........................................ 8-1 ARC Model Speed Analysis ..................................................................................................... 8-3 MAG Model Speed Analysis ..................................................................................................... 8-9 Comparison of MAG Planning Model Travel Times with INRIX and Microsimulation-based DTA Travel Times .............................................................................................................8 -16 NCTCOG Model Speed Analysis ........................................................................................... 8-21 PSRC Model Speed Analysis ................................................................................................. 8-28 SANDAG Model Speed Analysis ............................................................................................ 8-35 MPO Model VHT Summary Comparison ................................................................................ 8-42 Comparison of Modeled Travel Times with Google Travel Times .......................................... 8-43 Concluding Remarks ..............................................................................................................8 -55 Chapter 9 Concluding Discussion of Study Findings and Recommendations ............................................................................ 9-1 Perspectives on the Study Findings ......................................................................................... 9-1 User equilibrium traffic assignment models and their convergence ................................... 9-2 Feedback procedures and guidance .................................................................................. 9-3 Congested travel times produced by travel models ............................................................ 9-3 Validation of traffic assignment models .............................................................................. 9-4 Project evaluation and benefits estimation ......................................................................... 9-5 The Value of in-depth empirical review of models .............................................................. 9-5 Computational burden ........................................................................................................9 -5 Validation of travel models ................................................................................................. 9-5 Options for National Implementation ........................................................................................ 9-6 Research Suggestions .............................................................................................................9 -8

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