Brush Run Bridge
Gibson-Thomas designed the Brush Run Bridge project for PennDOT District 9-0 as part of an open end agreement. The existing structure, located immediately east of Hollidaysburg on SR 0022 (Blair Street), was a reinforced concrete T-beam bridge constructed in 1938. It had been rehabilitated in 1985 but was listed as structurally deficient.
The proposed structure was a prestressed concrete PA Bulb-Tee beam bridge with a 76’-0” span supported by integral abutments. The structure type provided for economical construction while increasing the hydraulic opening at the location by almost 40 percent.
After evaluating several traffic control scenarios, Gibson-Thomas and PennDOT agreed that a half-width construction would be the most effective method given the high traffic levels and lack of a suitable detour. However, the need to maintain two lanes of traffic required that the structure be overbuilt by approximately 11 feet on the upstream side. The phasing also required a temporary beam be placed under the deck prior to the first traffic shift.
A former railroad crossing was located on the far approach in the middle of the project design. Gibson-Thomas worked with PennDOT personnel to fully locate this feature (visible only by a 1 foot segment of rail in the vegetated shoulder) and incorporate its removal into the bid documents.
The Brush Run Bridge project was let in December 2016 and construction anticipated to be completed by Fall 2017.