As a major engineering subconsultant on an Interstate 78 under-clearance improvement effort involving multiple bridges in Pennsylvania, Erdman Anthony provided complete bridge and highway engineering services to improve the under-clearance of Midway Road Bridge over I-78. Accelerated Bridge Construction (ABC) techniques played a key role in completing the project.
The existing three-span prestressed box-beam bridge had a 13’ 8” under-clearance. It was replaced with a single-span prestressed PA bulb-tee beam superstructure supported on concrete abutments that provides a 16’ 6” under-clearance. The project also included reconstruction of 600 feet of approach roadway on each side of the bridge, reprofiling of the interchange ramps, and interchange-lighting modifications.
Conventional construction methodology would have used half-width staged construction to reconstruct the bridge and required two construction seasons to complete that work. Vehicles on the bridge would have been limited to a single lane, with temporary signals used to allow for bidirectional traffic. Traffic would have had to endure this inconvenience for nearly two years.
Instead, the ABC approach was used to minimize disruption to traffic during construction. That approach included the use of precast concrete abutments and footings, prestressed concrete beams, and precast deck panels with Ultra-High-Performance Concrete closure pours to facilitate a 60-day construction schedule. During those 60 days, the interchange ramps were closed, but all lanes of I-78 traffic under the bridge were left open to traffic.
A substantial public outreach program was implemented during the design phase to resolve concerns local business owners and residents had about the temporary closure. Ultimately, the 60-day closure was well received and construction was completed without delay.