Portland State University

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In this seminar, Dr. Porter will explore the interactions of geometric design decisions, speed, and safety. A performance-based approach to this topic will be considered given the availability of several key documents, including the Highway Safety Manual and TRB's Modeling Operating Speed: Synthesis Report as well as a significant body of published research. A historical look at the design speed concept will show that while the design speed definition has changed on more than one occasion, the same basic but flawed philosophy that relates design speed to a “safe speed” is still reflected in supplemental guidance related to design speed selection in current design policy. A conservative approach to establishing design criteria, currently used to address the range of driver, vehicle, and roadway conditions and capabilities that a designer must consider, will be demonstrated. Resulting operating speeds will be shown to be higher than design speeds for design speeds of approximately 55 mph or less. This outcome may be considered undesirable...

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Abstract: The geometric design of our urban arterials and collector streets can provide more room for nonmotorized travelers, make street crossings easier for pedestrians, and help to control traffic speeds, thus reducing pedestrian, bicycle and automobile crashes. In this seminar Mr. LaPlante will show how this can be done within existing rights-of-way and within tight maintenance and construction budgets, thus making better use of taxpayer dollars. The seminar also will address some of the myths about Complete Streets and how we can begin moving forward in making all our street networks complete.

Speaker Bio: John LaPlante is currently Director of Traffic Engineering for T.Y.Lin International, working out of their Chicago office. Prior to joining the firm in 1992, Mr. LaPlante had been with the City of Chicago for 30 years in various transportation engineering positions, including Chief City Traffic Engineer and Acting Commissioner of the new Department of Transportation. He has been involved in several national committees (PROWAAC, AASHTO Green Book Technical Committee, NCUTCD Pedestrian Task Force, and the TRB Pedestrian Committee) and was principal author of the AASHTO Pedestrian Guide. He has taught many courses as part of the...

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Abstract: Traffic safety engineering continues to rely on the traditional methods of design and operational guidelines, correlated to post-crash outcomes, in an attempt to understand the safety attributes of our roadway system.  The recently published Highway Safety Manual provides the newest source of methodologies and statistical models that can be applied to help predict or modify safety outcomes. Additionally, Road Safety Audits are a commonly used practice to gain the insight and experience of traffic and safety experts in an effort to avoid or solve a perplexing and/or unexpected safety problem.  Although none of these activities are completely void of human factors considerations, the ability to directly consider driver behavior, driver comprehension, and the impact of driver decision making in the analysis is incredibly complex and often omitted.  The use of full-scale driving simulators as a research and analysis tool may help significantly reduce the complexity of human factors-based consideration in the context of safety analyses and provide a new and effective tool to improve the safety of our roadway system. This lecture will consider several safety issues facing transportation agencies, namely median crossover crashes, permissive left-turn crashes, and roundabout safety, presenting thoughts and findings on related research.  Additionally, this lecture will integrate the attributes...