Award of the design-build contract to construct the US$850 million Parallel Thimble Shoals Tunnel in Virginia, USA, is expected next month (May) following submission by the four shortlisted joint venture contractors of their final technical and price proposals.

Alignment of Parallel Thimble Shoals Tunnel

Concept design of TBM excavation

The project involves construction by a choice of either immersed tube tunnel (ITT) or TBM of a 1,760m parallel two-lane traffic tube to increase capacity at one of the two tunnelled sections along the iconic 38km Chesapeake Bay Bridge Tunnel connection between Virginia’s eastern shore and the Norfolk and South Hampton Roads region.

The four prequalified consortia bidding for the job – which were shortlisted from an original list that also included the Salini-Impregilo/Healy/GLF JV, are:

• AWVC TunnelBuilders (Archer Western/Vinci Construction), who are successfully prequalified to present either an immersed tube (ITT) or bored tunnel technical and pricing proposal
• BTM JV (Bouygues/Traylor/Manson), ITT and bored tunnel
• Dragados/Schiavione JV, bored tunnel only
• SKW Tunnel Builders (Skanska/Kiewit/Weeks Marine), ITT tunnel only

The project is being financed 34% through bonds raised by the private owner – the Chesapeake Bay Bridge and Tunnel District (CBBTD) – against future toll income; plus additional TIFIA loans (33%), a US$50 million loan from the Virginia Transportation Infrastructure Bank (5%), and existing CBBTD capital receipts. Owner design is by Jacobs, Cowi and HNTB. Conceptual design of the TBM alternative specifies a machine of 13.9m diameter and a concrete segmental lining of 450mm thickness.

All the shortlisted companies have substantial experience of constructing similar infrastructure, with the SKW Tunnel Builders team (Skanska/Kiewit/Weeks Marine) currently nearing completion of the immersed tube Midtown Tunnel crossing of the Elizabeth River between Norfolk and Portsmouth, also in Virginia.

Once the winning bidder is selected a period of design-build final design will be entered into, with Notice to Proceed expected to be granted in July (2016). The project already has the necessary regulatory approvals, having been issued in July 2015 with a Finding of No Significant Impact (FONSI) by the Federal Highways Administration.

RFQs will be issued in less than two weeks time for construction of the USA’s latest mega-project – the mile-long billion-dollar Parallel Thimble Shoal Tunnel in Chesapeake Bay, Virginia.

37km Bridge Bay Tunnel features two tunnels

The new 5,710ft (1,740m) tunnel, which is already on a list of 45 major transportation projects that can expect to receive at least partial Federal funding, will double capacity at one of two tunnel choke points along the 37km-long Chesapeake Bay Bridge Tunnel connecting Virginia’s eastern shore and the Norfolk and South Hampton Roads region.

Additional funding is to come from the issuing of corporate bonds by the owner, Chesapeake Bay Bridge and Tunnel District (CBBT), which will be levied against future toll income. Currently 10,000 vehicles a day pay approximately $15 a time to use the crossing, a usage level that is expected to increase significantly in the coming years.

Procurement by CBBT for construction of the design-build project will allow successfully prequalified contractors/joint ventures to present either bored or immersed tunnel solutions. CBBT has already issued a Notice of Intent to Issue a Request for Qualifiers on 12 May. The deadline for submissions is 6 July. Up to four contractors or joint venture contractors will be shortlisted on 11 August 2015 to present full proposals and move to the final bidding stage. Contract award is expected in mid-2016.

Thimble Shoal Tunnel southern (Hampton) approach

Project scope will include:

• 5,710 ft (1,740m) of two-lane tunnel with a channel depth of 67ft (20m) plus 3ft (1m) of over-dredge and 10ft (3m) of cover over the tunnel
• widening of Portal Islands Nos. 1 and 2 to accommodate the new tunnel and associated ventilation buildings
• trestle extension spans from the existing wye-areas to the expanded portal islands with approximately 1,800 ft (549m) of 2-lane spans and approximately 400ft (122m) of 3-lane spans
• 1,300 ft (396m) of two 12-ft lanes of at-grade and depressed southbound roadway on both Portal Island Nos. 1 and 2 providing connection between the trestle extension spans and the tunnel portals

• tunnel finish, ventilation, lighting, emergency egress, approach lighting, electric primary and secondary power distribution system, emergency generators, tunnel drainage system, fire alarm and detection system, fire protection system, lightning protection, communication systems, intrusion detection and alarm system, Supervisory Control and Data Acquisition System (SCADA), Intelligent Transportation System (ITS), traffic monitoring and control devices, and island maintenance roadways.

Jacobs Engineering is appointed in a lead role as the owner’s Design Manager, with preliminary tunnel design being undertaken as part of the same contract by COWI and HNTB. Since these companies are all contracted to the owner team, they will not be allowed to play a part in any of the construction bids.

The Chesapeake Bay Bridge Tunnel was originally built between 1960-64 as a two-lane highway, mostly on raised trellises in the shallower stretches of the Bay, but featuring four bridges and a pair of mile-long immersed tube tunnels anchored between four man-made islands at the Bay’s two deep channel locations – to facilitate the passage of heavy shipping.

Original steel elements, manufactured in Texas, feature a 24ft wide two-lane road deck with 13ft 6in clearance

The trellis sections of the structure were dualled at a cost of $200 million between 1995-99, enabling repairs to the original road deck and the ability to divert traffic to the other deck in the event of accidents. However, the 51-year-old tunnels continue to act as a choke point where traffic must move from two lanes in each direction down to just a single lane, in bidirectional flow, a situation that has prompted CBBT to fast-track the installation of a parallel tunnel under the (southern) Thimble Shoal channel.

In addition, regular maintenance work results in 1,400 hours of tunnel lane closures every year, and no alternative route exists in the event of an accident inside the tunnel.

One of the likely bidders is the Parallel Crossing Consortium (PCC) of Skanska USA/Kiewit/Weeks Marine/Parsons Brinckerhoff, which last year (2014) submitted an unsolicited proposal to CBBT, valued at $800 million, for an immersed tube solution.

Chesapeake Bay Bridge Tunnel cross section

The same consortium is currently midway through construction of the nearby Midtown immersed tunnel linking Portsmouth and Norfolk under the Elizabeth River. In its proposal PCC stated: “No other team of companies and individuals can match PC2’s recent and proven experience in designing and constructing immersed tunnels, and can be prepared to immediately begin production of tunnel segments in 2016.” The 11 tunnel segments for the Elizabeth River Crossing project were manufactured in dry dock in Baltimore, from where they were barged to the jobsite along a route that passed over the Thimble Shoal tunnel.

CBBT examined the proposal, and opened a 90-day window for other joint ventures to submit rival bids, but after none were forthcoming a resolution was passed in April 2014 by the Board to terminate further consideration of PCC’s proposal.

The resolution was taken after both the CBBT’s financial adviser and its strategic adviser (infrastructure and engineering firm Moffat and Nichol) identified the project as “an ideal candidate for a design-build project delivery method,” rather than the equity financing arrangement as offered by PCC. CBBT was also concerned that the financial proposal as offered would have meant passing responsibility for maintenance for the new tunnel to the joint venture, rather than keeping the whole of the Bay Bridge Tunnel as a single entity. It was also felt that a competitive design-build procurement would ensure financial competition and the potential for finding extra value through innovative solutions.

The slightly shorter Chesapeake Channel Tunnel, to the north of Thimble Shoal, is considered to be of lesser priority because the shipping lane above it is not as frequently used and therefore it is less at risk of being damaged. In the medium term, however, there are plans to build a parallel tunnel at this location also.