Support for the Development and Implementation of an Access Management Program through Research and Analysis of Collision Data

The South Carolina Access and Roadside Management Standards (ARMS) provides standards and guidelines for permitting access encroachments onto South Carolina Department of Transportation (SCDOT) right-of-way. In April, 2013, SCDOT initiated research that would be used to update this manual with the intent that recommended changes could result in a reduction in crashes, injuries, and fatalities on South Carolina roadways. The research examined current and historical practices used by other transportation agencies with regard to access management. Using empirical data collected along several corridors that ranked highest in driveway related crashes, the researchers statistically analyzed and identified the correlation of access issues with crash data. Crash data were associated with driveways using complex Geographic Information System (GIS) modeling tools. The statistical analysis identified several significant independent variables that influence crash rates either positively or negatively. The results indicate that increasing the distance between driveways, increasing the number of entry lanes, and having a raised median will decrease driveway related crashes. Conversely, increasing driveway width, corridor volume and corridor speed limit will increase crashes. Similarly, a driveway with high turnover land use, a driveway with full access (as opposed to right-in right-out), and the presence of nearby signalized intersections will increase crashes. A micro-simulation analysis was used to investigate the operational performance of different driveway spacing policies adopted by various DOTs in the US. Experimental results indicate that driveway spacing has direct influence on the average travel speed of a corridor. Since reduced driveway spacing negatively impacts corridor travel speed, selection of a minimum spacing should consider its effect on the operational performance of the corridor. Benefit-cost analyses of two different access modification strategies following the Highway Safety Manual (HSM) procedures suggest that it is beneficial to convert a two-way left turn lanes (TWLTL) to a raised median. Similarly, it is beneficial to reduce the driveway density on a corridor. The research also reviewed SCDOT access waiver procedures. While the current process suffices based on a literature review it is evident that this process could be significantly streamlined and enhanced with a paperless system. Based on research findings, recommended changes to SCDOT Access and Roadside Management Standards (ARMS) are presented. It is anticipated that implementation of the findings of this research will result in long-term economic benefits, and improved traffic flow and safety.

  • Record URL:
  • Corporate Authors:

    Clemson University

    Department of Civil Engineering
    Clemson, SC  United States  29634

    South Carolina Department of Transportation

    Office of Materials and Research
    1406 Shop Road
    Columbia, SC  United States  29201

    University of South Carolina, Columbia

    Department of Civil and Environmental Engineering, 300 South Main Street
    Columbia, SC  United States  29208

    The Citadel

    Department of Civil and Environmental Engineering
    171 Moultrie Street
    Charleston, SC  United States  29409

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Sarasua, Wayne A
    • Davis, William J
    • Ogle, Jennifer Harper
    • Huynh, Nathan
    • Chowdhury, Mashrur
  • Publication Date: 2015-11-11


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; Maps; Photos; References; Tables;
  • Pagination: 128p

Subject/Index Terms

Filing Info

  • Accession Number: 01610800
  • Record Type: Publication
  • Report/Paper Numbers: FHWA-SC-15-02
  • Contract Numbers: SPR 706
  • Created Date: Aug 26 2016 10:02AM