Outstanding Rehabilitated Bridge - Spruce Run Bridge
Designer - W.E.C. Engineers, Inc.
Owner - PennDOT Disctrict 11-0
Contractor - J.F. Shea Construction
The project included the rehabilitation of three bridges; Spruce Run, Dilworth Run, and Fremont Street. This Nomination will focus on the Spruce Run bridge, which is the longest of the three. The Spruce Run Bridge is a 630 foot, 3 span-spandrel concrete arch, with sidewalks. The bridge carries 4 lanes of traffic, 2 lanes in each direction and carries SR 0065 over Spruce Run. The bridge deck was replaced in the 1980’s with a post-tensioned precast concrete plank deck with a roadway width of 48 feet that has four lanes without a median and no shoulders. Inspections showed that this deck leaked extensively which was responsible for the large amount of spalling in the substructure. In addition, the shear keys between the planks were failing and, due to the numerous deck joints in the precast planks, the public experienced a rough ride.
The purpose of this rehabilitation was to retrofit the existing precast parapets, (corrosion of the anchor bolts), repair broken shear keys in the concrete plank deck, and perform class AA cement concrete repairs on the substructure. The repair of the precast planks were more of a problem because of the broken shear keys; for this reason the planks could no longer be counted on to distribute the wheel loads to adjacent planks, greatly increasing the live load on the planks.
The options to retrofit the parapets were to widen them and strengthen them or a complete replacement. The second option that preserved the 12 foot wide lanes was selected. The deck repair options which were explored, included a complete replacement of the plank deck with a concrete slab, repair of the keys alone, and repair of the keys with a concrete overlay. The concrete overlay and key repair was selected because it was estimated to be half the cost of the deck replacement and also provided long-term improvements including, but not limited to, reduced drainage onto the substructure and an improved deck surface that repairing the keys without the overlay could not provide. The concrete overlay significantly reduced the water leakage through the deck to the substructure. The transverse reinforcement in the overlay and repair of the shear keys has restored the live load distribution onto the adjacent planks. Additionally, the smoothness of the deck was greatly improved by the removal of the numerous joints and the stiffening of the planks by the addition of the overlay.
During construction it was found, while repairing the shear keys, that several of the post-tensioned strands for the planks had corroded through at the joints. This was not a problem since we were adding an overlay with transverse reinforcement and providing dowels into the planks at each side (see attached drawings). Had the shear key repair option been chosen, the State would have had to re-evaluate the proposed repair, estimate the revised repair cost, and issue a work order for the repair.
One interesting note was the use of stainless steel reinforcement for the reinforcement that was used to anchor the slab to the parapet by extending the reinforcement from the slab into the parapet. The stainless steel was selected to prevent corrosion, however, it was very expensive compared to the alternate of epoxy coated reinforcement. The project unit cost was $7.50 per pound, while other bids were as high as $12.00 per pound.
The traffic control design was complicated by the fact that SR 0065 carries a high traffic volume, narrow lane widths with no shoulders, and the project limits included the three bridges of Spruce Run, Dilworth Run, and Fremont Street. This was spread out over approximately two miles in the heavily developed areas of Bellevue, Avalon, and Ben Avon. Access had to be maintained to all businesses and public roads throughout the project. Because the bridges are in close proximity to each other, the traffic control was extended between each bridge to maintain traffic safety throughout the two-mile length. In addition, pedestrian control was necessary because sidewalks were closed to the approaches of each bridge. Communication between PENNDOT, WEC Engineers, the contractor, municipalities, and the businesses was crucial to the successful completion of the project.
The traffic control was performed in two phases. The traffic was shifted from one side of the bridge to other as the repairs were completed. Special signage, arrow panels, and changeable message signs were employed to address the shifting lanes and access points to businesses.
Outstanding Rehabilitated Bridge
Spruce Run Bridge
Designer: W.E.C. Engineers, Inc.
Owner: PennDOT Disctrict 11-0
Contractor: J.F. Shea Construction