EPBM for Thimble Shoals parallel tunnel 10 Aug 2017

Peter Kenyon, TunnelTalk

Herrenknecht is selected by the Chesapeake Tunnel JV (CTJV) of Dragados and Schiavone to supply the 12.8m diameter EPBM that will excavate the 1,740m long Thimble Shoals parallel two-lane highway tunnel under Chesapeake Bay in Virginia, USA.

Roger Escoda, Project Manager for CTJV, told TunnelTalk: “The Technical Requirements were open to use either an EPB or a slurry machine. The choice was made by the contractor and based on our experience in the geological conditions depicted by the geotechnical baseline report at the time of the bid process.” The parallel drive under the central section of the 37km long Chesapeake Bay Bridge Tunnel is expected to encounter geological conditions comprising sand and soft and stiff clay layers.

Alignment of Parallel Thimble Shoals Tunnel
Alignment of Parallel Thimble Shoals Tunnel
Concept design of TBM excavation
Concept design of TBM excavation

Operating pressures of between 0.5 and 4.5 bar are expected as the EPBM completes its scheduled 12-month drive under the 20m deep shipping channel between two man-made islands. The existing pair of immersed tube tunnels, constructed between 1960 and 1964, provide single lane traffic in each direction and are a regular choke point as the two-lane traffic on the trellis bridge roadway filter into single lanes through the tunnel.

The EPB machine will be manufactured at the Herrenknecht factory in Germany and transported to the jobsite in October 2018 for a launch scheduled in Winter 2019.

“One of the greatest challenges of this project is logistics,” said Escoda. “The TBM will have to be assembled and disassembled on the small size of both the islands.

The launch island must also accommodate all the ancillary equipment for completing the tunnel. The team is highly focused on the logistical process on both islands in order to optimize production rates and reduce stoppage times.”

Three maintenance stops are scheduled as the TBM progresses, all of which will be performed under hyperbaric conditions. The machine will be fitted with two pressurized man locks each capable of accommodating six technicians and each capable of withstanding 5.5 bar pressure. With design of the machine ongoing, it is not yet decided which company will supply the manlocks.

Also in final design is the configuration of the cutting tools, which will include disc cutters, scrapers and rippers welded at different heights for different penetration rates, according to Escoda.

“The combination between the different kinds of cutting tools, along with the selected soil conditioning systems, will cope with expected geological conditions,” said Escoda. “Foam and bentonite will be used for soil conditioning to improve the distribution of pressures in the mixing chamber and through the 22m long screw conveyor and reduce wear.” There is no stone crusher and 24 openings on the cutterhead will provide an opening ratio of 45%.

A continuous conveyor mucking system will carry muck from the TBM to a muck bin at the working site for onward disposal, explained Escoda.

A contract to supply the concrete lining segments is awarded to CSI, which will establish a casting yard in Chesapeake for transport to the jobsite by truck. Moulds supplied by Cleco will cast the 460mm thick x 3.8m–3.9m long x 1.2m wide (18in x 12ft 6in- 12ft 11in x 6ft 6in) segments.

Final breakthrough is scheduled for winter 2020.

Revised bids for Thimble Shoals Tunnel 20 July 2016

TunnelTalk reporting

Revised technical proposals are in for the Parallel Thimble Shoals Tunnel in Virginia, USA, after those that were originally submitted by the three joint venture teams came in approximately US$290 million more than the Engineer’s Estimate.

Table 1. Initial and revised de-scoped bids
Bidder JV Partners May bid Revised bid
BTM JV Buoygues TP
1,016,046,800 848,452,987
AWVC Archer Western
1,071,683,000 785,883,000
Dragados Team Dragados USA
1,092,000,000 755,987,318

After receiving the original bids in May, all of which came at US$1 billion plus, the owner, Chesapeake Bay Bridge District (CBBD) “re-scoped” the project. In a statement released earlier this week CBBT said: “The District determined that the best interests of the Project would be served by re-engaging with all of these shortlisted teams to re-scope the Project after all of the original price proposals exceeded the cost estimate.”

The statement goes on: “The re-scoping of the Project was focused solely on the reduction of costs by reducing or eliminating unnecessary elements of the Project without compromising the quality or performance specified in the Technical Requirements of the RFP documents. Specifically, (1) scope changes that would increase the long-term cost of operating and maintaining the tunnel were not considered; (2) re-allocation of construction risks between the CBBT and the Design-Build Teams were not considered; and (3) changes to the Comprehensive Agreement, or contract, were not considered.”

CBBT will not at this stage identify exactly how the project has been scaled back, pending a special board meeting on July 27. This meeting is expected to evaluate the proposals and select one of the JV teams.

The re-scoped bids have turned the bidding table upside down – from being the highest bidder the Dragados Team is now the lowest bidder (having reduced its price by US$346 million), and from being the lowest bidder the BTM JV comprising Archer Western and Vinci is now the highest bidder (having reduced its price by approximately US$168 million).

All three bidders have proposed a bored tunnel solution, although the owner had indicated that an immersed tube solution would be considered.

Thimble Shoals contract award imminent 27 Apr 2016

TunnelTalk reporting

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
Alignment of Parallel Thimble Shoals Tunnel
Concept design of TBM excavation
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 for USA Bay Bridge Tunnel expansion 23 Apr 2015

Peter Kenyon, TunnelTalk

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
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
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
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.


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