THE JOB
32 track feet of grade crossing panels settled. This caused the adjacent asphalt pavement to fail and caused tripping hazards at the adjacent pedestrian sidewalk. The grading in the area was relatively good, however, the adjacent ballast was fouled, which caused water to accumulate under the crossing panels and wash out the sandy subbase material. The crossing had been replaced recently. Due to the urban, primarily passenger automobile traffic, there was a little deflection of the crossing panels from highway traffic. However, there were up to four inches of deflection from rail traffic loading.
The deflection from rail traffic loading caused the top edges of adjacent panels to be in compression with each other. This caused extensive spalling of the surface, which affected two of the panels. While not a functional problem for panel integrity, the spalled areas were within the sidewalk portion of the crossings and therefore posed tripping hazards.
THE CHALLENGE
The repair had to allow immediate vehicular traffic to facilitate a single-lane closure. The repair also had to allow for immediate resumption of rail traffic. The crossing served as a sand mine, so the settlement correction repair was designed around high service loads for heavy haul rail traffic.
Due to the scheduling constraints of the railroad, the repair method had to tolerate the potential for rail traffic during the repair.
THE SOLUTION
High-density polyurethane grouting to stabilize and lift the affected modular grade crossing panels, using CJGrout 48NHL.
Epoxy-augmented patching of the spalled areas to restore a smooth walkway for pedestrians.
CJGeo modular grade crossing repair crew filled the voids and corrected settlement in less than a day. Asphalt patching was done concurrently with polyurethane injection. The entire repair took less than two hours. The roadway and rail opened up immediately after the repair. Traffic control was done to accommodate pedestrians and roadway traffic.
Two trains passed through the crossing over the panels being repaired during the repair. This did not affect the integrity of the repair.
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