Safety Impacts of Access Management Techniques in Utah

• Authored by:  Dr. Grant G. Schultz (PhD)
• Co-authored by:  J. Lewis , Tim Boschert

Schultz , G., J. Lewis, and T. Boschert, “Safety Impacts of Access Management Techniques in Utah,” Transportation Research Record: Journal of the Transportation Research Board, No. 1994, Transportation Research Board of the National Academies, Washington, D.C., (2007, pp. 35-42). [Schultz, G. and J. Lewis, Assessing the Safety Benefits of Access Management Techniques, Brigham Young University, Utah Department of Transportation (2006)]

      This report focused on the relationship between access management techniques and safety performance for eleven roadway segments in the state of Utah. The authors evaluated six locations with recently implemented access management techniques in a before-and-after analysis along with five control locations without access management.  Installation of raised medians and driveway consolidation were the two most prevalent techniques applied at the six treatment sites.  The analysis included several data variables, including crash frequency, crash severity, crash rate, driveway density, and annual average daily traffic (AADT).

      The research results indicate that driveway consolidation and raised median installation are not always associated with a reduction in crash rates or crash frequency.  The results did show, however, that a reduction in crash severity and a shift in crash types can be expected after implementation of these two access management techniques.  It was noted that the crash frequency at nearby intersection increased at some locations due to a shift in the location of left-turning traffic, however the reduction in crash severity contributed to an overall improvement in safety performance for both the roadway segments and nearby intersections.