Projects
Median Crossover / CODES Study
| Project Information | Project Photos | ||
Project Status: Starting Date: Ending Date: Duration: |
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Description:
Verify median crossover crashes and match with
CODES medical cost information to generate “real” incident costs.
Rationale:
Letter from the Federal Highway Administration (FHWA) requiring data on crossover crashes.
Overview
Crossover median crashes are a growing concern for transportation
officials across the country. The nature of a crossover crash -- a
vehicle traveling at a high speed that traverses a median and enters the
opposing lanes of traffic -- creates a situation that is high cost, both
financially and in terms of human injury. Some states have begun to
erect median cable barriers on all highway sections where median
crossover crashes have been found to be a common occurrence. In South
Carolina, crossover crash fatalities fell from 70 two years prior to the
cable barrier installation to only 8 fatalities during the three years
of implementation. A median width of 60 ft, which South Carolina has
used as their standard for placing cable barriers, is the Wisconsin
standard non-barrier median width for highways with a speed limit
greater than 55 miles per hour (mph).
At the start of this research effort, the magnitude of crossover crashes in Wisconsin was unknown. Furthermore, the characteristics and causes of these crashes had not been studied. Median barriers are installed on Wisconsin highways that meet a certain median width/ADT requirement; however, crossover crashes still occur across wide medians that exceed these standard. California has adopted a standard that recommends median barriers on sites if more than 1/2 crossover crash per mile per year occurs, regardless of the median width and ADT. There is a need in Wisconsin to identify how many crashes are occurring, at what sites, and develop a median barriers standard as a potential countermeasure to these crash types.
The objective of this research was to identify and evaluate crossover crashes in Wisconsin, determine the relationship between the crashes and median width, and quantify the costs of crossover crashes to establish benefit/cost ratios between the crashes occurring and potential safety improvements. It was hypothesized that crossover crash frequency decreased with increasing median width. Crash reports for Wisconsin for the three most recent years available, 2001 thru 2003, were visually inspected to determine if the crash either entered or crossed the median. Over 15,000 crash reports were individually reviewed. The highways segments under consideration included most of the divided highway system in Wisconsin including Interstates 39, 43, 90, 94, U.S. Highways 10, 12, 14, 18, 41, 51, 53, 141, 151, and WI Highways 23, 29, 30, 35, 54, 57, 172, 441.
The results of the crash analysis identified 631 crossover crashes over the three-year study period. An examination of the relationship between median width and crossover crashes adjusted for vehicle miles traveled (VMT) showed that there was not the direct relationship between crash frequency and median width as originally hypothesized. A large portion of the crashes occurred at median widths of 50 ft and 60 ft, the state’s design standard widths for freeways and expressways. Evidence suggests that median widths in this range may not be adequate requiring safety improvements to the roadway cross-section.
Crossover crashes were plotted statewide to depict the location of “hotspots”, or locations where frequency rates exceed the California standard. Statistical models, similar to the California model, are being proposed as an additional measure to gauge whether or not one of several potential countermeasures may be necessary.
Over half of the crossover crashes (53%) involved a personal injury and 7% of the crashes were fatal, resulting in 53 deaths. Additional dissemination of the data, modeling of the crash data and Crash Outcome Data Evaluation System (CODES) analysis is being completed to determine the financial costs of the crossover crashes. Benefit/cost analysis will then be done to evaluate proposed safety improvements to the roadways.
Documents:
| Document Name | Files | Date Posted |
|---|---|---|
| A Safety Analysis of Cross-Over-the-Median Crashes on Wisconsin Highways - Project Summary - November 4, 2004 | Median Crossover - Project Summary - 11/04/2004  (PDF, 1.31 MB) |
11/23/2004 |
| Analysis of Median Crossover Crashes in Wisconsin - Research Report - June 2005 | Median Crossover - Research Report - June 2005 (PDF, 7.84 MB) |
08/23/2005 |
| An Analysis of the Safety Impacts and Costs of Crossover Median Crashes in Wisconsin - Presentation - WisDOT - September 28, 2005 | Median Crossover - Presentation - WisDOT - 09/28/2005 (PDF, 2.39 MB) |
10/07/2005 |
| I-43 Ozaukee County Median Crossover Crash Report January 2001 - June 2006 - Research Special Report - August 2006 | Ozaukee County - Research Special Report - 8/9/2006 (PDF, 624 KB) |
08/10/2006 |
| A Five-Year Analysis of the Safety Impacts of Crossover Median Crashes in Wisconsin - Research/Special Report - June 2007 |
Latest Report (PDF, 7.7 MB) |
04/11/2008 |