Replacement of two deteriorating three-span bridges on a major interstate was required for this design-build project. Using traditional construction methods, interstate traffic would have been rerouted over a 90-mile detour. To limit disruptions, accelerated bridge construction techniques were mandated.
Use of precast concrete AASHTO Type II girders with a lightweight concrete deck met the requirements for the two-span bridge. The shallow-depth girders minimized fabrication time and allowed an increase in the bridge’s vertical clearance without changing the interstate profile. Girder span was increased by use of the lightweight deck, further minimizing construction time. A hydraulic jacking system was used to slide the main span and approach slabs in place, keeping closure time to a maximum of 7 hours.
This is the first bridge replacement project in the U.S. in which the approach slabs were slid in along with the main span. The accelerated construction system and use of precast girders helped reduce the overall project cost. The construction cost was approximately 60% of the engineer’s estimate.