Challenges Overcome at Greensburg Pike Demolition

In early November, after enduring months of utility relocation delays, Brayman closed the existing Greensburg Pike Bridge in Turtle Creek, PA, sending nearly 7,500 vehicles per day on a lengthy detour.

The demolition of the 800' long, eighty-eight year old structure, comprised of four truss spans and two girder approach spans, was necessary to allow for construction of the approaches to the new bridge that was completed earlier in the year.

Working through its own set of challenges, the southernmost truss span of the old bridge was demolished in a few weeks. A series of temporary support towers and rigorous torch cutting kept the project on schedule and allowed work to begin on a major retaining wall that was critical to the completion of the project. That accomplishment was short lived as the wall work was soon suspended to make room to demolish the adjacent 200' long truss span over three very busy Norfolk Southern railroad tracks.

The demolition plan was challenging due to the limited track time. Nevertheless, the truss was stripped and prepped for removal. Due to the railroad's busy schedule, the main truss needed to be removed in three consecutive nights with limited track outages on dates specified by Norfolk Southern. Further complicating the operation, the significant skew of the truss, coupled with very limited space around the active tracks, created difficult access for the numerous man lifts and cranes.

Partially disassembled, the first of two 275-ton crawler cranes was tracked under the bridges, reassembled, and positioned tightly between the existing pier and the adjacent active railroad track. The swing radius for this crane was further reduced by energized overhead electric lines.

The second 275-ton crawler crane was set atop a causeway constructed in the adjacent Turtle Creek channel and tracked into position only a few hours before the first pick, due to a week of unpredictable ice jams and high water levels.

A 75-ton crane was situated on the new bridge deck. Temporary bracing was installed and anchored to the new bridge to support the truss.

After completing the first night, the second night was cancelled due to heavy rains and rescheduled for the following weekend. Once back to work for the second and third nights, with the pressure of the overall schedule impact growing, severe liquidated damages looming, and under the close watch of various railroad personnel, the team persevered and completed the very difficult torch cutting in sub-zero temperatures. The truss halves were removed within the allotted track outages and the critical wall work resumed.

The next truss section, spanning Turtle Creek, was completed during normal day shift work using this same process. Most recently the last truss span, located over land, was carefully removed utilizing an excavator mounted shear working within very tight clearances between the new bridge and an adjacent apartment building. Temporary towers were used to help support the weight of the excavator as it was positioned on the approach girder spans, while a strategically sized rock pile was used to help control the severely skewed truss as it was sheared apart and felled to the ground.

Numerous challenges were overcome on this project. But most importantly, this difficult bridge demolition was completed safely, on time and within budget.