Seminary Road over I-395 Bridge Replacement and HOV Ramp Design-Build

ALA designed the replacement for the existing superstructure with a lightweight, reinforced concrete deck on continuous, curved, composite steel plate girders. The new superstructure was designed to accommodate forces and movements, including the connection between this bridge and the HOV Ramp bridge, such that the performance and maintenance are optimized for a 75-year service life. The geometry of the hammerhead pier, with respect to size and location, was developed to provide horizontal and vertical clearance from the crash barrier to the bottom of the pier cantilever and ensure that it did not project into the lanes below, per VDOT Bridge Manual V5 P2. Additionally the pier was designed so that the barrier would act as pier protection for deflection so as not to impact the stem of the pier. As such, the new superstructure was designed to accommodate forces and movements, including the connection between this bridge and the HOV Ramp bridge. The steel plate-girders are supported by laminated elastomeric bearings on reconstructed reinforced concrete pedestals on the existing piers and abutments. The existing abutment backwalls were replaced to accommodate the new tooth expansion joints and new full-width (curb to curb) VDOT-standard structural approach slabs.

The new structure also was designed to support new light poles, traffic signals and HOV warning gates. New scuppers, a bridge drainage system and troughs at the abutment joints were detailed for the new bridge. The bridge plans included concrete repair details for the deterioration on the existing piers, which consisted of cracks, spalls and delaminated concrete.

ALA also developed load rating analysis and reports for the staged bridge construction and the complete “As-Designed” bridge using LRFR method in accordance with VDOT IIM S&B-86.