Joliet Transportation Center
- 80 Rock Sockets
- 180 WF of Sheeting
- 180 LF of Bracing
- 2 Tiebacks
Our role on this project was to provide a design/build earth retention system for two pedestrian tunnels running underneath the railroad tracks at the Joliet Transportation Center and bearing on limestone bedrock. Due to the railroad’s schedule, only two brief track outages were allowed for the earth retention installation. During the first 8 hour outage we installed 180 wall feet of sheeting simultaneously at both tunnel locations to the top of bedrock.
Between the first and second outage, two 45-foot long tiebacks were drilled from the adjacent street level for the north tunnel to strengthen an existing retaining wall that would support the earth retention system’s bracing. As a result of the shallow bedrock, achieving a toe penetration of the sheeting was impossible. Instead we utilized an innovative method to create rock sockets for each of the sheet piles by drilling into bedrock through a 6-inch diameter pipe that was welded along the face of each sheet. This solution enabled us to eliminate a lower level of bracing saving the critical time for the second outage to install the upper level of bracing and the precast tunnels (by others) within a strict 48-hour window.
Reducing the level of bracing necessary to one level proved to be crucial to allow time for excavation, the setting of the precast tunnel pieces, and to backfill. This project turned out to be a major success and accomplishment for the Stalworth Team.