LDG was selected by PennDOT District 11 to provide preliminary engineering, final design, and construction consultation services for operational improvements to the McLaughlin Run Road (SR 3004)/ McMillan Road (SR 3034) intersection in Upper St. Clair Township, Allegheny County.

Planning & Preliminary Engineering

The existing signalized intersection experienced significant congestion, especially during peak hours. Based on current conditions and future traffic projections, LDG developed several alternatives which varied from a signalized intersection with designated turn lanes to a dual lane roundabout. Because the roundabout provided the best value to PennDOT and minimized impacts to the surroundings, while providing the best future levels of service for all traffic movements, PennDOT directed LDG to advance the roundabout option into the preliminary engineering phase of the agreement.

Design

The roundabout was located south of the existing signalized intersection and the approach roadways were realigned horizontally and vertically
to minimize the overall construction footprint for the four approaches. The engineering and related tasks included preparing construction plans and documents for the intersection and two bridge replacement structures.

Construction

The level of difficulty for this project was compounded by a deteriorated bridge on one of the intersection legs that was subject to frequent overtopping, a deteriorated box culvert on another leg, and numerous overhead and underground utilities. LDG successfully worked through these issues and prepared the final construction plan sets, as well as the project’s constructability reviews.