This research compares two interchange types, the Tight Urban Diamond Interchange (TUDI) and the Four Phase Single Point Urban Interchange (40SPUI). The 40SPUI is referred to in this report as a Single Point Urban Interchange with Frontage Roads (SPUI/F). The objectives of this research were to: (1) evaluate the SPUI/F based on available accident data and conflict analysis techniques, right-of-way and construction costs, and operating efficiency; (2) compare the performance of the SPUI/F and the TUDI; (3) evaluate current SPUI/F design assumptions and operation and recommend design and/or operational changes to enhance performance; and (4) evaluate the interchange form selection (pre-design) process and recommend changes where appropriate. The research found no significant difference in the safety aspects of the two interchange types. The SPUI/F generally did not perform as well operationally as the TUDI, with increased SPUI/F delay as the distance between frontage roads increased.

This study focused on the control of the off-ramp right turn movement at single point urban interchanges (SPUIs) without frontage roads. The objective of this research project was to evaluate the safety and efficiency of traffic control for off-ramp right turns. For the purposes of this project, two common forms of off-ramp right turn traffic control were investigated: signal control and yield control. The process followed during this research focused on two main aspects of the off-ramp right turn movement: safety and operations. The project was composed of the following stages: literature review, safety analysis and operation analysis. Literature Review: A literature review was conducted to provide the research team a broader perspective on other studies concerned with this aspect of SPUIs. The review was looking for the various traffic controls and interchange configurations that could particularly affect the safety and operation efficiency of off-ramp right turn movement. Safety Analysis: Long-term trends in crash occurrences and short-term observations of conflicts at six study sites (12 off-ramp locations) were analyzed. Crash rates and conflict rates were determined in order to compare and contrast the two means of assessing safety as well as how they relate to the type of the traffic control used at the off-ramps. Operations Analysis: Detailed traffic data collected at the study sites were used to calculate actual delays for off-ramp right turn movements at the study sites. These field data were also used to conduct simulations of interchange sites, which supplemented the calculations based on the limited sample of study sites. The simulation models provided a means of testing different combinations of off-ramp right turn control types and overall interchange conditions in order to determine the effects of signal and yield control.

Contains summaries of the knowledge regarding the effects of 128 road safety measures. This title covers various areas of road safety including: traffic control; vehicle inspection; driver training; publicity campaigns; police enforcement; and, general policy instruments. It also covers topics such as post-accident care, and speed cameras.

TRB's National Cooperative Highway Research Program (NCHRP) Report 672: Roundabouts: An Informational Guide - Second Edition explores the planning, design, construction, maintenance, and operation of roundabouts. The report also addresses issues that may be useful in helping to explain the trade-offs associated with roundabouts. This report updates the U.S. Federal Highway Administration's Roundabouts: An Informational Guide, based on experience gained in the United States since that guide was published in 2000.

Contains summaries of the knowledge regarding the effects of 128 road safety measures. This title covers various areas of road safety including: traffic control; vehicle inspection; driver training; publicity campaigns; police enforcement; and, general policy instruments. It also covers topics such as post-accident care, and speed cameras.