SECTOR | TRANSPORT, WATER - US
early real estate acquisition, adoption of best value contract structures such as A+B contracts (design- build), contract co-ordination, and reduction in back-of-house, ancillary space and station size. The initiatives have saved more than US$1.3 billion.
VIRGINIA - HRBT Main tunnelling for the Hampton Road-Bridge Tunnel Expansion (HRBT) project, in Virginia, has been nearing completion. The project involves construction of a twin tube
road tunnel with a single TBM. The parallel tunnels haven been bored sequentially - the TBM being turned around and re-launched to drive pack to the original starting point, and soon to reach that destination. The HRBT project is being developed by the Virginia
Above:
TBM nearing the finish on HRBT, in Virginia.
Below:
Single bore large- diameter pick for BART extension, in California.
Early work commences in late 2025, with heavy
civil construction starting in early 2026 and tunnel boring expected to begin in 2027. Phase 2’s first construction contract was awarded
in January 2024 for utility relocation work. The third contract covers construction of the underground space for the future station at 106 Street and Second Avenue. The fourth, and final, contract will cover the fit-out of the three stations, at 106, 116 and 125 Streets, and the systems for train service. The contract is in design. Second Avenue Subway Phase 2 is scheduled to
open in September 2032. Phase 1 opened in 2017. MTA said lessons learned
would help to complete Phase 2 tunnelling, including addressing utility relocation upfront to reduce the risk of unexpected costs or delays. Additional cost containment initiatives in Phase 2 include reuse of a tunnel portion built in the 1970s,
Department of Transportation (VDOT), and in a recent project update said that the TBM, ‘Mary’, was in the final stages and boring on the uphill climb through fine grained soils, such as clay. In June, the TBM set a record of 66 rings installed in a week, achieved in large part because of the work of the slurry treatment plant, which processes about 600 tons of soil per ring before the spoils are transferred to barges for transport to final disposal. VDOT said the slurry treatment plant made “make
quick work of the coarse-grained sandy soils found deep beneath the bay bottom.” It added though that the top layers of the bay stretch the plant to its limits in quickly processing the spoils, as fines require more time to separate from the slurry. Construction of the first tube saw the TBM
complete in 51 weeks, and it may be the second tube is bored slightly faster. Fit-out works are underway inside the first tunnel, including placement of the tunnel’s roadway base along the entire length of the tube, which allows completion of the tube’s new egress structures and drainage systems.
24 | January 2026
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