An Evaluation of Right-Turn-In/Right-Turn-Out Restrictions in Access Management

• Authored by:  R. Lyles
• Co-authored by:  B. Malik , A. Chaudhry , G. Abu-Lebdeh , M. Siddiqui

Lyles, R., B. Malik, A. Chaudhry, G. Abu-Lebdeh and M. Siddiqui, An Evaluation of Right-Turn-In/Right-Turn-Out Restrictions in Access Management, Prepared for the Michigan Department of Transportation, Michigan State University (2009)

[ see also Malik, B., M. Siddiqui and R. Lyles, “An Evaluation of Driveway Turning Restrictions in Access Management Using Microsimulation,” 90th Annual Transportation Research Board Meeting, Washington, D.C. (2011)]

This study evaluates the safety and operational impact under various access configurations to provide basic guidelines as to when left-turns at driveways should be prohibited to maintain traffic flow and regular operations. The safety considerations were found to be less significant compared to operational concerns, as the crash reductions that might be expected from access restrictions appeared to be relatively modest. The importance of review of crash history by site is emphasized.

Traffic simulation models were developed using VISSIM to analyze the operational impacts of driveway turning restrictions at corner and mid-block sites. The results indicate that the lesser the corner clearance, the more negative the impact on driveway-related delays. Also, the negative impact on driveway delay due to mainline volume increment was more severe as compared to the increment in driveway volume. The impact on the driveway operations was worse when the number of lanes on the adjacent roadway was less than 5 or 4. The right-turn (in or out) driveway traffic was not critical from either an operations or safety perspective due to fewer conflict points. General guidelines are proposed for prohibition of left-turns in and out for various combinations of mainline and driveway traffic volumes and corner clearances.