A feature story in the Construction Equipment Guide, the national publication of the construction industry, recently highlighted the work of SEPTA’s Crum Creek Viaduct Replacement Project in Swarthmore.

The high-profile, $89.9-million project requires the complete replacement of the 925-ft. long, 100-ft. high Crum Creek Viaduct. The structure being replaced, which was built in 1895, underwent repairs in 1983 but was in dire need of replacement to safely carry SEPTA’s passengers on the Media/Elwyn commuter rail line.

The original bridge on the site was a pre-Civil War era, five-span timber arch truss bridge on masonry piers. It was owned by the Philadelphia, Baltimore & Washington Railroad (PW&B RR) and later acquired by the Pennsylvania Railroad.

The project’s prime contractor, Walsh Construction of Chicago, rented drills and equipment from the Aldan office of Equipment Corporation of America (ECA).

Walsh began construction on the substructure in summer 2015 and is working aggressively toward an etched-in-stone deadline of summer 2017.

Despite the variety of construction processes involved, drilling the foundations for new footings, piers, and abutments was the key to the project.

Walsh rented the BG 18 H and BG 20 H Premium Line drilling rigs because they were light enough to navigate rough terrain with adequate hydraulic output to core through hard rock of up to 25,000 psi. The low headroom capability of the BG 18 H was determined to be optimal for drilling in work areas with height restrictions.

Walsh is tasked with building a new viaduct beneath the original structure before demolition can commence. The keystone of the project is foundation work for the substructure.

The topography surrounding the viaduct is complicated by steep inclines, wetlands, the meandering Crum Creek and a narrow, snake-like access road, all encapsulated within a densely wooded area that is a designated arboretum. One of Walsh’s main challenges was drilling foundations in hard rock beneath the viaduct with limited headroom near the east and west abutments.

Walsh has demonstrated considerable environmental sensitivity throughout the project because of active involvement by Swarthmore College. Although SEPTA had the right-of-way available for the viaduct, it negotiated with the college to use a necessary adjacent piece of land instead of using eminent domain. In addition to obtaining permitting from multiple agencies, the contractor will have to rebuild wetlands and replace up to 6,000 trees and shrubs

SEPTA will shut down service for roughly 10 weeks this summer to allow Walsh to install new girders, bridge deck, and catenary towers. Rail cars will travel over the new viaduct by Labor Day 2016. Walsh will conclude the project by summer 2017 with demolition of the existing structure, removal of the access road, and restoration of the site to original condition.

Click here to read more about the construction of the Crum Creek Viaduct.