Parallel Thimble Shoal Tunnel (PTST)
Virginia, USA
TBM EPB
Construction method
1.935 m
Excavated length
11.89m/13.25m
Internal Diameter / Excavation
1 TBM
TBM number
45 m
Depth
The Parallel Thimble Shoal Tunnel (PTST) project eliminates a major bottleneck on the Chesapeake Bay Bridge-Tunnel, one of the most iconic pieces of transportation infrastructure in the United States.
The project involves constructing a new tunnel that enhances the connection originally established in the 1930s—which was previously improved by the creation of the Bay Bridge-Tunnel in the 1960s. The new structure spans 1,935 meters beneath the Thimble Shoal Channel, doubling the existing crossing's capacity and significantly improving the infrastructure's safety and service levels.
FlatironDragados (USA) is executing the work using a large-diameter Earth Pressure Balance (EPB) tunnel boring machine, implementing a particularly complex solution due to the tunnel's shallow cover, its sub-sea alignment, and the ground's poor geotechnical characteristics.
The project includes two traffic lanes, shoulders, and a separate emergency evacuation corridor, thereby bolstering the resilience and operational capability of this strategic East Coast corridor.
Project data
Project data
·
1,935 m tunnel length
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New tunnel beneath Thimble Shoal Channel
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267,000 m³ excavation volume
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11.89 m internal diameter
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13.25 m excavation diameter
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Excavated using an EPB TBM
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Two traffic lanes plus shoulders
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Dedicated emergency evacuation corridor
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Part of the Chesapeake Bay Bridge-Tunnel corridor
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