The Pennsylvania Turnpike Commission recently demolished and rebuilt a 60-year-old structurally deficient bridge within a 55-hour timeframe using innovative sliding bridge technology designed by Larson Design Group (LDG). The accelerated bridge construction “roller” technique was a first for the Turnpike and one of the few bridge slides to have been achieved in the commonwealth over the past three-plus decades. LDG teamed with Road-Con, Inc. to replace the bridge on the northeast extension of I-476 in Lehigh County over the course of a single weekend, which successfully minimized disruption to tens of thousands of motorists and avoided stiff financial penalties. The project included construction of a 115-foot span steel girder bridge on steel supports.
“The Accelerated Bridge Construction process is a cost-effective way to replace bridges within a short timeframe while reducing worker exposure in construction zones which in turn improves safety for workers and motorists alike,” Turnpike CEO Mark Compton said in a Turnpike statement. “It also eliminates the need for months or years of cattle chutes, single-lane traffic patterns and other restrictions for motorists.”
The ABC technique allowed workers to replace a bridge in one weekend rather than a year or more of construction. During the 55-hour construction, workers demolished the old bridge and slid the new spans into position. For several months leading up to the replacement, crews constructed the new spans next to the existing bridge.
LDG’s Quentin Rissler served as project manager. Based in LDG’s Lititz, PA office, Rissler and the LDG team oversaw the completion of pre-bid design for the temporary support structure and slide-in details, as well as construction phase services.
In the last two decades, the Turnpike has completed dozens of bridge-replacement projects to ensure the safety and integrity of the critical structures. Although this is the first time the Turnpike has used the ABC engineering technique, PennDOT has successfully deployed the technique on other state roadways in the past.
LDG is an engineering, architecture, and survey firm with offices in four states. The firm is employee-owned and provides innovative solutions to facility, transportation, land development, infrastructure, and environmental needs. More: www.larsondesigngroup.com