January 2012

As work progresses on the bench, or bottom portion of the tunnel, tunneling crews are beginning work on the waterproof membrane and final lining near the western portal.

The first step is to apply 7 mm of waterproofing membrane that is made of a polymer-based material over the top of the smoothed shotcrete that has already been applied throughout the length of the tunnel. For the final lining, the contractor will cast a wall of reinforced concrete by assembling a rebar cage, constructing formwork to contain the concrete and pouring the concrete through holes in the form and then plugging the holes when the wall space is filled.

The formwork will glide forward as work on the lining progresses.

December 2011

Excavation of the top portion, or topheading, of the Fourth Bore was completed on November 29th, 2011. Crews are currently excavating the bottom portion, or bench, of the tunnel from the west side using the project’s excavator and from the east side with the roadheader. Click here for details on this progress.

As excavation on the west side proceeds crews will begin working on the waterproofing and concrete lining that must be in place before the final concrete is poured for the arch and roadway surface.

Work on the safety cross passages between bores four and three is ongoing. To date, crews have completed excavation of two of the seven cross passages.

July 2011

Excavation of the first of seven cross passages between bores four and three has started. The cross passages will serve as a safety feature for motorists when the new tunnel opens to traffic.

Click here to view the construction photo gallery.

Click here to view the current activity archive.