Slide Rail System Enabled Deep Tunnel Excavation For Safe Storm Sewer Installation Beneath Busy Roadway

A Denver, Colorado based utility contractor recently completed construction and installation of a new 30-inch storm sewer line beneath an existing roadway in an extremely busy section of Westminster, Colorado. Ensuring the stability of the existing roadway and surrounding structures, as well as the safety of its employees, the contractor determined the most efficient and cost-effective way to approach this challenge would be performing a 42-inch tunnel excavation beneath the roadway.

The contractor estimated the launch shaft for the tunnel needed to be 40-ft long and 24-ft wide and excavated to a depth of 24-ft to provide the necessary working room to complete the project. After reviewing several options to shore the launch shaft, the contractor selected a site-specific engineered slide rail system from National Trench Safety. The slide rail system would provide positive soil support during the excavation, which was key due to the presence of the existing roadway and adjacent utility structures.  The slide rail system would provide proactive soil support throughout the excavation process to help prevent undermining the congested road. Further addressing the site challenges, the contractor used steel plates along the open end of the shaft in coordination with the slide rail system and the NTS engineered plan, to provide the necessary soil support along the excavation wall where the tunnel would take place. The contractor was extremely satisfied with the slide rail system and its performance.