Asphalt Patching Rectifies Loading Dock Pavement Problems
Project Challenges – Substantial deflection and stresses caused by passing rail cars and heavy truck volume caused over time substantial surface fatigue failure and other problems on a section of the pavement lanes serving a loading dock in Southeastern Wisconsin. Also known as alligator cracking, surface fatigue cracking can be an indicator of pavement structural failure. In its early stages, fatigue cracking causes pavement roughness and permits moisture to infiltrate the pavement profile. If left unaddressed, fatigue cracking can progress through the asphalt layers to the pavement base, creating small chunks of asphalt pavement easily dislodged by vehicle or rail traffic. The resulting potholes can cause vehicle damage, present myriad safety and liability issues, and subject the pavement to additional structural deterioration. The dislodged asphalt on this project sometimes got stuck in the railroad tracks, endangering rail traffic, and was often dragged by the truck traffic across the pavement lanes and onto adjacent pavement – asphalt projectiles dangerously poised for launch from the roadway. In late fall, winter, and early spring, snow and water often entered the potholes and froze, causing potential safety hazards for vehicles, drivers, and employees. A final project challenge: The loading dock is part of the project owner’s business lifeline. Lost economic opportunities were not an opt ion, making minimizing business interruption during the repair paramount. Actions Taken – The Paving Division of Munson, Inc. had few options to consider for rectifying the loading dock pavement problems. Pavement degradation and the loss of subgrade support in the affected pavement areas eliminated surface patching as a repair option and a structural overlay presented time, budget, and elevation issues. Instead, the Munson Crew employed removal-and-replacement hot asphalt patching, removing the deteriorated asphalt, preparing and compacting a proper structural aggregate subbase designed to withstand the deflection and stresses caused by the rail and truck traffic, and applying a hot fresh asphalt patch of suitable thickness in two layers. The two-layer approach requires compaction for each layer, resulting in a slightly longer construction schedule and increased labor costs, but produces a stable and highly durable patch repair.
Results – Though the asphalt patching interrupted dock traffic for about a half day, it provided a cost-effective repair solution enabling increased safety, exceptional performance, reduced liability, smoother rail and truck traffic, and extended pavement service life.