CR-111 at LIE Intersection Capacity Improvements


Location: Suffolk Manorville County
Client: Suffolk County Department of Public Works
Completion Date: 2008

The project consisted of an interchange improvement study in order to determine potential improvements to the area. The interchange experiences traffic congestion during the Friday PM peak period and the Sunday PM peak period. The traffic congestion is caused by motorists traveling to and from the Hamptons area of Long Island. Several site visits and traffic counts were performed at critical periods in order to accurately model the existing conditions. Future traffic volumes were estimated for ETC, ETC+10 and ETC+20.

Several alternatives were considered for the study. One alternative was to coordinate the traffic signals along CR 111 in order to minimize the delay. Other alternatives considered incorporating cloverleaf ramps into the intersection. It was determined that the cloverleaf ramps would improve the intersection but at a significant cost. A unique feature of the design was the potential closing of a local roadway in close proximity to the project area. It was determined to designate the roadway as allowing rights out only in order to minimize its impact on adjacent intersections. Another factor which needed to be incorporated into the traffic analysis was the anticipated construction of a commercial development immediately south of the project area. A trip generation study was performed to determine anticipated traffic volumes which were then incorporated into the traffic analysis for the corridor. The study will be used by the County as a decision making tool for future capital programs.