Broadway Subway Project Main Street Station
The Broadway Subway Project’s Main Street Station required micropile tie-down anchors and a forepoling umbrella system to prepare for tunnel boring machine breakout. TerraCana operated two drill rigs in parallel beneath a temporary deck on active Broadway Street, completing the full scope in three months to stay ahead of the arriving TBM.
The Challenge
The forepoling umbrella system had to be fully installed before the tunnel boring machine could break into Main Street Station. Any delay to the forepoling would delay the TBM, making this one of the most schedule-critical scopes on the Broadway Subway Project.
The work took place inside a deep excavation beneath a temporary deck supporting active traffic on Broadway Street, with multiple site activities running concurrently. Two 25-ton micropile drill rigs had to be hoisted into the excavation by crane before work could begin.
The Solution
TerraCana deployed two micropile rigs working in parallel, a Soilmec SM22 and a Casagrande C7-XP2, and ran extended shifts to complete the forepoling umbrella ahead of the tunnel boring machine’s arrival. The micropile anchors and forepoling system were designed by the owner’s engineer, EXP.
The team installed 27 micropile tie-down anchors at 219mm diameter to a depth of 11 metres. The forepoling umbrella consisted of 48 grouted steel pipe piles (114mm and 168mm diameter, up to 6 metres long) and 90 grout-only piles (168mm diameter, 13.5 metres long).
The Outcome
Technical Specifications
Key Outcomes
Project Partners
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