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APPENDIX D Supplemental References This section provides supplemental references for projects and final reports that also looked at speed reduction treatments at intersections, through varying methods described in the report. Data from some but not all of the following papers were included in Sections 3 and 4. The pur- pose of this section is to provide readers with additional sources of information for further research or insight into possible speed treatments both at intersections and on roadways. Arnold, Jr., E. D. and K. E. Lantz, Jr. Evaluation of Best Practices in Traffic Operations and Safety: Phase 1: Flashing LED Stop Sign and Optical Speed Bars. Virginia Transportation Research Coun- cil, Charlottesville, 2007. This report looks at the impacts of flashing LED signs and optical speed bars at intersections and road segments identified as "unsafe." Initial results found limited statistically significant speed reduction. Researchers recommend that both flashing LED stop signs and optical speed bars be considered as safety countermeasures at appropriate locations where higher than expected numbers of crashes, crash rates, or excessive speeding occur. Federal Highway Administration. Pavement Marking Demonstration Projects: States of Alaska and Tennessee. FHWA Project 475980-00001, pmdemo/ PMDemo-index.html (accessed August 2007). Using field tests of volunteers and simulator studies, this study tested the impact of brightness of pavement markings and edge line width on driver speeds along rural road segments. The analysis of driver preference rankings from both the field and simulator studies led to the subjective finding that drivers favor more and brighter markings as they negotiate curves on two- lane rural roads at night. In conjunction with FHWA, Texas Transportation Institute is looking to evaluate the multiple impacts of pavement markings using sites in Alaska and Tennessee. Scheduled for completion in 2009, this study is mandated by Section 1907 of SAFETEA-LU. Further information can be found on the project website at: b-kuhn/pmdemo/PMDemo-index.html. Fylan, Fiona and Mark Conner. Effective Interventions for Speeding Motorists. Road Safety Research Report No. 66. Department for Transport, London, 2006. This report reviews human psychological factors for speeding, components of interventions that are most likely to change this behavior, and the effectiveness and extent of identified inter- ventions. This paper presents a list of components that national speed awareness schemes should include, and how such schemes should be evaluated. Gannett Fleming, Inc. Collision Avoidance System Evaluation Report. PennDOT, Harrisburg, 2004. An analysis of the collision avoidance systems (CASs) utilized at two locations in Pennsylva- nia to address limited sight distance concerns at rural unsignalized intersections is provided. The 98

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Supplemental References 99 CAS was effective in reducing speeds for drivers approaching an intersection with a lit sign. Once users understood the system, speeds increased at the intersection approach with an unlit sign. Stakeholders and users considered this system an effective way of alerting drivers of oncoming traffic without signalizing the intersection. Joerger, Mark. Adjustment of Driver Behavior to an Urban Multi-Lane Roundabout. Oregon Department of Transportation, Salem, 2007. This analysis of the first multi-lane roundabout installed in Oregon looked at possible reduc- tion of speed variability on approach from the previous signalized intersection and reduction of driving errors as drivers became accustomed to the new installation. Researchers found that there was no consistent change in speed variability at approaches to the roundabout from the previ- ous signalized intersection. As was hypothesized, however, driving errors and confused behav- ior declined in the six months studied. Rakha, Hesham Ahmed, Bryan Katz, and Dana Duke. Design and Evaluation of Peripheral Transverse Bars to Reduce Vehicle Speed. Transportation Research Board, National Research Council, Washington, D.C., 2006. This research project examined whether perceptual countermeasures such as pavement mark- ing patterns have the potential to reduce vehicle speeds. The markings resulted in a decrease in overall vehicle speeds. There also were reductions in speed with vehicles traveling with headways greater than four seconds. Reductions were found to be higher on interstate and arterial road- ways than on local road sites. Ullman, Gerald L. and Elisabeth R. Rose. Effectiveness of Dynamic Speed Display Signs in Per- manent Applications. Texas Transportation Institute, College Station, 2004. An analysis of the effectiveness of dynamic speed display signs (DSDSs) installed in a variety of speed zones was presented in this report. Overall, average speeds were reduced by 9 mph at the school speed zone, although elsewhere the effect of the DSDSs was less dramatic, with average speeds reduced by 5 mph or less. The results of this project suggest that DSDSs can be effective at reducing speeds in permanent applications if appropriate site conditions apply. Vest, Adam, Nikiforos Stamatiadis, Adam Clayton, and Jerry Pigman. Effect of Warning Signs on Curve Operating Speeds. Research Report KTC-05-20/ SPR-259-03-1F. Kentucky Transportation Center, University of Kentucky, Lexington, 2005. This study evaluated the use of several warning signs and methods to identify those that have the most significant impact on reducing vehicle speeds when traversing a horizontal curve. The most effective treatments were found to be transverse lines, the new combination horizontal alignment/advisory speed sign, and flashing lights on both existing and new signs. For all three treatments, a reduction in the average of the speeds over the 85th percentile was observed.