Broadway Subway nears the official start of tunnelling using boring machines

May 31 2022, 10:04 pm

The start of tunnel boring for SkyTrain’s Millennium Line Broadway Station grows near.

The provincial government stated today all of the parts of the two tunnel boring machines (TBMs) that will be used to dig twin tunnels have now arrived.

Final preparations are now being made to create the concrete foundation for the tunnel boring pit and staging area at the intersection of Great Northern Way and Thornton Street, which doubles as the eventual underground volume for Great Northern Way-Emily Carr Station.

Large cranes have now been erected at the tunnel boring pit in preparation for lifting the TBM component parts into the pit for assembly.

After assembly later this summer, the machines will be launched separately from the pit — travelling a distance of five km, passing through four subway station volumes currently being excavated under Broadway. The TBMs will end their journey at Cypress Street, just east of the future Arbutus Station.

If all goes as planned, the twin tunnels will take about one year to dig.

broadway subway skytrain tunnel boring machine tbm

Broadway Subway tunnel boring pit preparation progress at the site of Great Northern Way-Emily Carr Station, as of May 29, 2022. (Kenneth Chan/Daily Hive)

In its bulletin today, the provincial government adds both machines will be named in the coming weeks, following tunnel boring tradition, and a ceremony some time this summer will mark the official start of tunnelling.

Each machine is six metres wide, 150 metres long (about twice the length of an Expo/Millennium line station platform), and weighs nearly one million kilograms. The TBMs will dig about 18 metres length of tunnel per day, with excavation generating about 200,000 cubic metres of soil that will be moved on a conveyor system out of the tunnels at the tunnel boring pit.

The tunnels will be about 15 metres below ground, reaching a maximum depth of 20 metres at Broadway-City Hall Station to dive beneath the Canada Line tunnel.

Each TBM will be manned by eight to 12 staff controlling the machines and monitoring the vitals of the operation.

The machines were built by German manufacturer Herrenknecht, and the tunnel contractor is Italian tunneller Ghella.

The project also includes a 700-metre elevated guideway span between the existing VCC-Clark Station and the tunnel portal just east of Great Northern Way-Emily Carr Station.

Ghella is part of the project contractor consortium with Spanish engineering giant Acciona, which together are building the project under a $1.73 billion contract with the provincial government. After geotechnical studies, planning and design work, and land acquisition costs are accounted for, the entire subway project carries a total cost of $2.83 billion.

Upon opening in late 2025, the Broadway Extension of the Millennium Line to Arbutus is anticipated to see about 140,000 boardings per day.

Until the Millennium Line is further extended to the University of British Columbia, passengers will complete the remaining journey to the campus on a truncated 99 B-Line route from the Arbutus Station bus exchange. TransLink previously projected the truncated 99 B-Line will reach capacity during peak hours upon the opening of the subway in 2025.

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