Stop the trains – there’s a 2,400-tonne structure coming

A huge concrete tunnel weighing 2,400 tonnes (half a million pounds) was pushed and nudged into place below a CN Railway line in Burlington, west of Toronto near Lake Ontario on Thanksgiving weekend. After the last commuter train had gone by the spot on Friday afternoon, three rail lines were removed, leaving one track open for freight trains.

The King Road Grade Separation Underpass project involved digging out 800 loads of fill below the railway tracks to leave space for a four-sided concrete structure measuring 17 metres wide, 18 metres long and 8 metres high. Built on site, the structure was pushed into the tunnel using a unique system of hydraulic rams.

Consulting engineers on the project are Hatch Mott MacDonald and AMEC Earth and Environmental.

The push started on Sunday afternoon and took four hours. After it was in place, crews started to fill in the space around it and regraded the area above.

Nearly 100 trains pass over the tunnel every day, which is why the city chose Thanksgiving weekend to make the big move when traffic was relatively light. By Tuesday morning at 5 a.m. the commuter tracks were back in place.

The next stage of the project is to build an aqueduct to allow a tributary of Indian Creek to flow over the realigned road on the north side of the railway. The new King Road is scheduled for completion in 2013.

To watch a video of the “B-Roll” click here.