Work continues for the new light rail transit line that will soon see some impressive engineering feats. Here’s how you tackle a transit ‘push box’.
Before the major work, comes the ‘pre-push’.
One of the most complicated technical elements of the Hurontario light rail transit (HuLRT) route is getting started with advance work on the ‘push box’.
Last year, Metrolinx News gave readers an overview on the ‘push box’ that is planned to be built at the Port Credit GO Station as part of the future HuLRT project.
As a refresher, the push box is a large, hollow concrete box that will be pushed underneath the Lakeshore West rail tracks at the Port Credit GO Station. This will create a tunnel under the rail tracks, allowing the future HuLRT line to move without disrupting rail service on the tracks above.
The structure itself is complete, currently awaiting to be pushed into place. Before the official push can begin, a ‘pre-push’ needs to take place. The pre-push will involve pushing the structure from where it currently sits to the retaining wall, just south of the rail corridor.
The pre-push activity, similar to the actual push, is carried out through a ‘jacking operation’. The push box has been constructed on a launch slab. The launch slab is the concrete platform that the push box will sit on top of and acts as a smooth level surface to push the box to its final position under the rail tracks. The launch slab is designed to minimize friction during the push.
Hydraulic jacks will then be installed in-between the push-box and the thrust block, the piece that will carry out the pushing. The thrust block is a two-metre thick structure that is used to transfer forces during the pushing of the push box to the surrounding soil.
This whole operation will happen this month (Feb.) and will take approximately three days.
This same operation will be used during the official push, where the push box will be pushed from just south of the rail corridor to underneath the tracks. This process is expected to take approximately four weeks to complete.
The final product will create the tunnel for the station that will be under the tracks without disrupting the GO rail service on the tracks above.
Story by Erika D’Urbano, Metrolinx Senior Advisor