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Current
Status CURRENT WORK ACTIVITIES The Research Team has completed the tasks identified in the research approach. The final report prepared by the Research Team is currently scheduled for publication by NCHRP during the summer of 2003. Currently the Research Team is working with the National Committee on Uniform Traffic Control Devices (NCUTCD) to discuss the findings of the NCHRP 3-54 research effort and to examine the potential incorporation of the flashing yellow arrow in the Manual on Uniform Traffic Control Devices as an alternate to the permissive circular green indication. Driver Simulation Study Status Using full-scale dynamic driving simulators located at the University of Massachusetts (UMass) and the Texas Transportation Institute (TTI), the Research Team developed a virtual driving environment to further test driver understanding of select PPLT displays and associated behavior. Study participants were required to navigate a virtual world containing various signal displays, different arrangements and locations, and opposing traffic, with the intent of evaluating driver performance at pre-selected intersections controlled by PPLT displays in an actual driving environment. The researchers at UMass and TTI were tasked with each testing 200 drivers of various demographic backgrounds. The Research Team has completed the driver simulation confirmation studies. Working Paper 7, which summarizes the confirmation study findings, is now available for downloading in the documents section. FLASHING YELLOW ARROW IMPLEMENTATION STATUS UPDATE! Although the Research Project is nearly completed, the Research Team continues to support the implementation of the experimental flashing yellow arrow display at key study locations across the county. Field implementation of an experimental flashing yellow arrow display was conducted to field test a display that had shown promise in safety and driver comprehension in previous task activities and had ranked high in the Engineering Assessment. Volunteer agencies were sought from across the United States to install and operate the experimental flashing yellow arrow display. In conjunction with use of the experimental display (which required permission from the Federal Highway Administration (FHWA) to operate), “before” and “after” studies were completed at each intersection where the flashing yellow arrow display was installed and at nearby control sites. These “before” and “after” studies allowed the Research Team to quantify the impact of the changeover from the MUCTD circular green indication to the flashing yellow arrow indication. Working Paper 8, which summarizes the implementation study findings, is now available for downloading in the documents section. Photos from Broward County, Florida and Beaverton, Oregon and their implementation of the experimental flashing displays are summarized below. Broward County, Florida Broward County, Florida successfully implemented the flashing yellow arrow at three study intersections in early June 2002. The study intersections are:
Shown below are photos of County Staff installing the new flashing yellow arrow display. The photos, provided by Lawrence Hagen of Broward County, show the 5-section display that was at the intersection, County Staff adding the new flashing yellow arrow display, and the intersection approach with the new display in use.
Click here to see how the signal works:
Research Team staff from the University of Massachusetts visited the site prior to installation of the new displays to record operations with the "doghouse" display that had previously been in use. UMass staff will return later this summer to conduct an "after" study at each of the three study intersections. Beaverton, Oregon The City of Beaverton, Oregon also successfully implemented the flashing
yellow arrow at three study intersections in April 2002. Shown below is a
photo of City Staff installing the new flashing yellow arrow display at the
intersection of SW Wilson Avenue/SW Allen Boulevard in Beaverton and the
intersection approach after installation was completed.
Beaverton was the third public agency in Oregon to implement the experimental display, with the Oregon Department of Transportation having implement at two locations in Woodburn, Oregon and Jackson County implementing at multiple sites. PAST WORK ACTIVITIES Agency Survey The Research Team mailed out over 325 surveys to city, county and state representatives in urban areas with a population of 180,000 and greater and received back 180 of them. A return rate of 55 percent! The returned surveys represent 107,219 of the approximately 300,000 traffic signals located within the United States. Analysis of the data indicates that approximately 27 percent of those 107,219 traffic signals use PPLT phasing on at least one approach. For more information on the Agency Survey read Working Paper 2. Engineering Assessment The Research Team, in concert with the project panel, developed a multitude of questions that were considered key to determining the "best" signal display for the PPLT control. Some of these questions would be answered through more traditional experimental procedures, where as other questions would be answered by applying engineering judgment based upon current practices. Working Paper 1 identifies the methodology and assumptions used to answer these questions. Working Paper is a work-in-progress and is therefore not final. There are several rankings that have been discussed with the project panel and thus will be changed in the next revision of Working Paper 1. Request for Additional Information The Research Team has received an over-whelming response from the traffic engineering community to support this research project through their willingness to participate in data collection; including supplying crash data, video taping intersections, and administering the photo survey (Task 3). A partial listing of those agencies includes: Oregon Department of Transportation Photographic Driver Survey Data collection for the Photographic Driver Survey was completed in Troy, Michigan; Dover, Delaware; Portland, Oregon; Dallas and College Station, Texas; Orlando, Florida; Cupertino, California, and Seattle, Washington. Additional surveys were administered by volunteers in Eugene, OR; Boca Raton, FL; Jackson, MS; Raleigh, NC; and Corpus Christi, TX. The objective of the photographic driver survey was to evaluate the different PPLT signal displays used in the United States. The evaluation explored driver understanding of the signal indications under a variety of conditions. The conditions varied through the use of protected left-turn indications, permitted left-turn indications, through movement indications and PPLT signal display arrangements. More than 2,465 drivers took the survey. At each of the project team's survey locations, approximately 300 drivers completed the survey. Because each survey respondent was presented with 30 scenarios, a total of 73,950 responses were recorded. The findings and conclusions of the photographic driver survey are documented in Working Paper 3. Traffic Operations The Research Team collected and analyzed left-turn saturation flow rate, start-up lost time, response time, and follow-up headway data at the eight geographic locations where the driver survey was administered (Dallas, Dover, Delaware, Oakland County, College Station, Seattle, Portland, and Orlando). The results of the traffic operations studies are documented in Working Paper 4. Traffic Conflict Study The Research Team collected conflict data at 24 study intersections to quantify the left-turn conflict rate and event rates for different PPLT signal displays and indications. Traffic conflicts are traffic events involving the interaction of two or more drivers where one or both drivers take evasive action to avoid a collision. Traffic events are unusual, dangerous, or illegal non-conflict maneuvers such as red indication violations, backing up, hesitation on signal change, and slowing considerably in a traffic lane. The results of the Conflict Study are documented in Working Paper 5. Crash Data Analysis The Research Team conducted a limited evaluation of crash history associated with the unique displays used in PPLT. The research panel members and research team recognized that current crash reporting techniques do not adequately document causes of a crash as they relate to traffic signal operation, much less the particular signal display. The objective of the crash analysis was to determine and compare left-turn crash rates associates with various PPLT signal displays. The crash analysis are documented in Working Paper 6. INTERIM REPORT The Research Team distributed an Interim Report that documented all of the work conducted up to August 1999. The interim report documented and summarized all of the work previously distributed in the working papers (1 through 6). The interim report provided recommendations on how to proceed in the project. FIRST PANEL MEETING The Research Team met with the Project Panel members on October 26, 1999 in Washington, DC. SECOND PANEL MEETING The Research Team met with the Project Panel members on January 8, 2003 in Washington, DC. [Home] For comments or questions regarding this web site, please contact Chris Brehmer.Copyright 2002 by Kittelson & Associates, Inc. All rights reserved.Reproduction for commercial use in whole or in part without permission is prohibited. This site hosted by: |
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