TxDOT Research Library - Publication Details

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Title:

Design and Operation of U-Turns at Diamond Interchanges in Texas

Report No.:

FHWA/TX-17/0-6894-1

Authors:

by Jonathan Tydlacka [and seven others]

Published:

2017

College Station, Texas

Texas A&M University. Texas Transportation Institute (TTI)

Type:

Online document

1 PDF (310 pages)

Online Access:

https://library.ctr.utexas.edu/hostedpdfs/tti/0-68...

Access Note:

6.4 MB

Summary

Summary

U-turn lanes are commonly provided at diamond interchanges to reduce delays for U-turning traffic and for the interchange as a whole; however, there are currently many unknowns related to their design, operation, and use. This project provides the Texas Department of Transportation (TxDOT) with implementable guidelines for designing and operating U-turn lanes at diamond interchanges. Researchers identified and investigated several factors affecting U-turn lane use, determined the performance and limitations of U-turn lanes under various geometric and operational conditions, and determined the anticipated effectiveness of proposed solutions to U-turn operational issues. Researchers then developed and structured guidelines for inclusion in the TxDOT Roadway Design Manual and other manuals addressing access management, design, and operations of U-turn facilities. This investigative effort included a cross-sectional safety analysis of existing U-turn configurations that provided valuable insight into factors contributing to U-turn safety. Along with the safety analysis, researchers developed a self-calculating spreadsheet tool that can be used to predict U-turn safety performance under various conditions.

Publ. Place

College Station, Texas

Contents

Chapter 1. Introduction --
Chapter 2. Factors Affecting U-Turn Lane Use and Potential Solutions to Operational Issues --
Chapter 3. Characteristics of U-Turn Lanes under Various Conditions --
Chapter 4. Operational Effectiveness of Solutions --
Chapter 5. Safety Evaluation of U-Turn Design --
Chapter 6. Development of U-Turn Guidelines --
References --
Appendix A. Questions Document for State-of-the-Practice Review --
Appendix B. Volume Data from Study Sites --
Appendix C. Base Data from Simulation --
Appendix D. Simulation Results from the Countermeasures --
Appendix E. Research Forest Volume Data for Signal Timing Analysis --
Appendix F. Description of Variables Used in Safety Analysis --
Appendix G. Summary of Crash Data for Operational Study Sites --
Appendix H. Supplemental Statistical Analysis

Notes

"September 2017"

Study Number

TxDOT Research Project 0-6894

Study Title

Guidelines for Design and Operation of U-Turns

Study Sponsor

Lead University

TTI