HRCP making good progress on HRBT scheme29 July 2020
Preparations are well under way in Norfolk, Virginia for the expansion of the Hampton Roads Bridge-Tunnel (HRBT) scheme – the largest transportation project ever undertaken by the Virginia Department of Transportation.
Crews and subcontractors working for Hampton Roads Connector Partners (HRCP) are busy on the South Island constructing a 20m-deep assembly and launch pit. From here in February 2022, a TBM will begin boring the 2.4km-long twin tunnels beneath the estuary of the Elizabeth and James rivers.
It is envisaged the TBM will take around a year to tunnel from the South Island toward the North Island (Norfolk to Hampton), excavating through the soft, over-consolidated sands and clays of the Yorktown formation. After a period of around four months needed to turn the TBM around, it will take the machine another year to bore a parallel tunnel back to the South Island.
Forming part of the US$3.8bn HRBT expansion project, the addition of the twin two-lane 14m-diameter tunnels is aimed to ease congestion in the existing tunnels to which they will be parallel, although 15m deeper.
The ambitious project has so far not suffered any slowdown from the coronavirus pandemic. Due for completion in 2025, it also includes replacement and rebuilding of 28 marine bridges and widening of 10 miles of Interstate I-64.
The original tunnels, built in 1957 but added to in the 1970s, comprised 23 immersed steel tubes entered through portals on two man-made islands (North and South). These are both linked to the mainland by trestle bridges.