A Case Study of Safety Impacts of Congestion on Urban Freeways in Tampa Bay, Florida

Document Type

Conference Proceeding

Publication Date



This paper describes how, in the year 2004, there were 3,257 traffic fatalities and 252,902 traffic crashes in the State of Florida. Among these crashes, 362 fatalities and 39,322 crashes occurred in the Tampa Bay region. According to Texas Transportation Institute’s Urban Mobility Report 2005, the Tampa Bay area was among the top 20 metropolitan areas with the most annual delays per traveler. Past studies have reported an increase in crash rates with the increase in level of traffic congestion. This study was conducted by Center for Urban Transportation Research (CUTR) at the University of South Florida in order to determine the safety impacts of traffic congestion on the urban freeways in the Tampa Bay region. Florida Department of Transportation and Mobility Technologies have collected detailed data for the traffic flow on I-4, I-75 and I-275 in the Tampa Bay region for the past few years. This data was used to determine the level of congestion during different time of day. Mobility Technologies has also maintained a database of highway crashes on the freeway system. In this study, these two data sets were analyzed to determine the impact of congestion on the safety of the above mentioned roadways. A relationship, established by the study, between congestion level and traffic crashes would assist decision makers in implementing congestion mitigation strategies to maintain congestion levels below certain threshold values, beyond which, the likelihood of traffic crashes is high.

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Citation / Publisher Attribution

ITE 2007 Technical Conference and Exhibit, Compendium of Technical Papers, Washington, D.C., March 2007.