Determination of the Offset Distance Between Driveway Exits and Downstream U-turn Locations for Vehicles Making Right Turns Followed by U-turns

Determination of the Offset Distance Between Driveway Exits and Downstream U-turn Locations for Vehicles Making Right Turns Followed by U-turns
Author: Jian John Lu
Publisher:
Total Pages: 194
Release: 2005
Genre: Driveways
ISBN:

Florida increasingly uses restrictive medians and directional median openings on multi-lane highways to manage left turn egress maneuvers from driveways and side streets. By installing non-traversable medians and replacing full median openings with directional median openings at various locations, Florida prohibits direct left-turn exits onto some major arterials. The purpose of this research was to evaluate how the offset distance between driveway exits and downstream median openings or signalized intersections impacts traffic operational and safety performance. The primary objective is to determine optimum offset distances to facilitate driver use of Right Turn Followed by a U-Turn (RTUT) maneuvers, specifically investigating (1) traffic operational performance, based on the evaluation of vehicle travel time at various offset distances, and (2) safety performance, based on the evaluation of traffic conflicts and crash data. The focus of this research was on urban or suburban multi-lane divided arterials. Researchers studied the impacts of offset distance under four different scenarios: 4-lane divided roadways accommodating U-turns at median openings, 4-lane divided roadways accommodating U-turns at signalized intersections, 6 or more-lane divided roadways accommodating U-turns at median openings, and 6 or more-lane divided roadways accommodating U-turns at signalized intersections.

State of the Practice in Highway Access Management

State of the Practice in Highway Access Management
Author: Jerome S. Gluck
Publisher: Transportation Research Board
Total Pages: 124
Release: 2010
Genre: Highway engineering
ISBN: 0309143055

This synthesis reports how various agencies have acted on the various components of an access management program, what have been barriers to action, and how new efforts might improve implementation of access management strategies. Primary focus areas considered are legal and legislative bases, contents of policies and programs, implementation aspects, reported effectiveness of program implementation, and profiles of contemporary practice. This synthesis reports on the state of the practice with respect to planning, highway design, development review and permitting, and other focus areas where access management is typically incorporated. The emphasis is placed on states, but counties, municipalities, and metropolitan planning organizations are also considered.

Evaluating the Effects of Prohibiting Left Turns and the Resulting U-turn Movement

Evaluating the Effects of Prohibiting Left Turns and the Resulting U-turn Movement
Author: Mashrur A. Chowdhury
Publisher:
Total Pages: 90
Release: 2003
Genre: Roads
ISBN:

The objective of this research was to evaluate the operational and safety effects of restricting direct left turns from a driveway and providing alternatives to accommodate the left turn deterred traffic. This study was conducted in three phases: survey of state agencies, operational analysis, and safety assessment. Very little operational difference was found between no restrictions on direct left turns versus the restrictions with the U-turn alternative movements from site to site. While changes in the traffic volumes on the mainline had an impact in specific instances, no definite trends were apparent. As a result of all findings in this study, it is proposed that alternatives must be evaluated on a site-by-site basis. This study also found the jughandle design to be a superior alternative for accommodating left-turn deterred traffic for multi-lane divided and undivided sites compared to mid-block or intersection U-turns. The safety assessment revealed that a right turn followed by a U-turn movement is safer than the direct left turn.

Evaluation of Safety Strategies at Signalized Intersections

Evaluation of Safety Strategies at Signalized Intersections
Author: Raghavan Srinivasan
Publisher: Transportation Research Board
Total Pages: 48
Release: 2011
Genre: Technology & Engineering
ISBN: 0309213452

TRB’s National Cooperative Highway Research Program (NCHRP) Report 705: Evaluation of Safety Strategies at Signalized Intersections explores crash modification factors (CMFs) for safety strategies at signalized intersections. CMFs are a tool for quickly estimating the impact of safety improvements.