SR 1004 Sugar Camp Road Bridge Design
Peters Township, Washington County, PA
Stahl Sheaffer provided engineering services for the replacement of a single-span cast-in-place reinforced concrete arch carrying Arrowhead Trail over SR 1004, Sugar Camp Road. Three structure alternatives were investigated during preliminary design. The options included a precast reinforced concrete arch under fill, a single-span composite prestressed concrete I-beam bridge on pile supported integral abutments, and a single-span prestressed concrete adjacent box beam bridge on cantilever abutments. The selected replacement is a 145'-6" single span structure consisting of three 33/71.5 PA Bulb-Tee Beams on integral abutments. To complete the design process, coordination was required with PennDOT District 12-0 to obtain Structural Adequacy and Foundation Approval.
The three structure alternatives considered included: Alternate No. 1, a precast reinforced concrete arch; Alternate No. 2, a single-span composite prestressed concrete I-beam bridge with a reinforced concrete deck on integral abutments; and Alternate No. 3, a single-span composite prestressed concrete adjacent box beam bridge with a reinforced concrete deck. The three alternatives were evaluated to determine the most appropriate replacement structure.
Upon evaluation of the criteria, Stahl Sheaffer concluded that Alternate No. 2 was the most feasible alternative. This alternate selection was significantly less expensive than Alternate No. 1 and Alternate No. 3. Additionally, this structure type easily accommodated SR 1004 if the horizontal alignment is improved to eliminate the S-curve within the existing structure. Therefore, Stahl Sheaffer recommended replacing the existing structure with Alternate No. 2, a single-span composite prestressed concrete I-beam bridge on integral abutments using two 33/85.5 PA Bulb-Tee beams spaced at 8’-8 ¼” o.c. with an 8.0” reinforced concrete deck and a 14’-0” curb-to-curb.
The horizontal and vertical geometry of SR 1004 was based on a 35-mph design speed. There is an approximate grade separation of 37 feet between Arrowhead Trail and SR 1004. With a minimum under clearance of 16’-6”, there is trivial effect on vertical profile based on the existing geometry constraints. The trail and SR 1004 will be replaced on similar vertical profiles.