PennDOT’s Pittsburgh Regional District Makes First Use of Self-Propelled Transport Techniques to Speed Up Week-Long Bridge Replacement Over Busy U.S. Route 19

​Faced with replacing a bridge over busy U.S. Route 19 in Allegheny County, PennDOT's District 11 chose to use self-propelled modular transporters (SPMTs), marking the first of their use in Pennsylvania and fulfilling a key component of PennDOT's accelerated bridge construction (ABC) initiative.

Because U.S. Route 19 carries approximately 27,000 vehicles a day to and from downtown Pittsburgh, Interstate 79, and Pittsburgh International Airport, minimizing closures during the replacement of the Shaler Street Bridge was an absolute necessity. Using the SPMT process allowed the bridge replacement to require only two weekend closures instead of long-term corridor restrictions and closures.

To make the short-term closures possible, Shaler Street's new bridge beams and deck were assembled at a nearby site off of U.S. Route 19's mainline. The two components were then moved onto the new support structures using SPMT units. To demonstrate how the process works, the project team created a YouTube video detailing the Shaler Street bridge replacement.

Notably, U.S. Route 19 is divided at this location, a challenge for the SPMTs. "We were dealing with a bifurcated road; we evaluated the move path for a traversable slope and clearance between the moving bridge and the existing buildings," said Project Manager Chris West.

Additionally, West added that PennDOT's Right of Way unit also had to reach an agreement with a property owner so a staging area close to the project could be created.

As a result of hard work and ingenuity, PennDOT and its project team addressed these construction challenges and were able to provide commuters access to U.S. 19 much more quickly using accelerated bridge construction (ABC) techniques. Using prefabricated bridge materials produces shorter construction schedules and helps ensure consistency in product quality. PennDOT's use of ABC techniques on this project is but one example of how PennDOT is delivering improved and more timely infrastructure to the people of Pennsylvania.

ABC is part of the Every Day Counts initiative championed by the Federal Highway Administration (FHWA), and its methods are used in a variety of projects, including quick construction box culverts, prefabricated bridge elements and systems, bridge slides, and geosynthetic reinforced soil-integrated bridge systems (GRS-IBS).

Although the replacement of the Shaler Street Bridge is the first time SPMTs were used in Pennsylvania, PennDOT's District 8 has been making use of other ABC techniques in recent years. One example is the Harrisburg region's deployment of ABC techniques to replace the 98-year-old Herr Street Bridge in 10 days. Herr Street is a key link for commuters entering and leaving the Capitol Complex area of Harrisburg. ABC was also used to replace the Pennsylvania Route 581 bridge over 10^th Street in Lemoyne, Cumberland County—a project that lasted just a few weeks instead of months. And, PennDOT's District 5 in the Lehigh Valley region used ABC techniques to replace six bridges over Interstate 78 in Berks County.

"We are proud to deliver the replacement of the Shaler Street Bridge as part of the U.S. Route 19 Improvement Project in the City of Pittsburgh," said PennDOT District 11 Executive Cheryl Moon-Sirianni.  "By using this innovative Accelerated Bridge Construction method we did not only dramatically reduce the replacement time of this structure, but it also served as the catalyst for future use of this technology across Pennsylvania."