Dragados/Schiavone Awarded Thimble Shoal Tunnel Contract

A submarine passes through Thimble Shoal Channel as the jack-up barge for the tunnel borings works in the background. A new tunnel will be constructed across the channel to increase capacity and allow unimpeded shipping.

A submarine passes through Thimble Shoal Channel as the jack-up barge for the tunnel borings works in the background. A new tunnel will be constructed across the channel to increase capacity and allow unimpeded shipping.

The Chesapeake Bay Bridge and Tunnel Commission has awarded the Dragados Team a contract to construct a new parallel tunnel at the Thimble Shoal Channel. This award marks the end of a 3.5-year project development and procurement process that leveraged a lowest price, technically acceptable acquisition strategy. The Dragados Team, a joint venture composed of Dragados USA Inc. and Schiavone Construction Company LLC, submitted the lowest price proposal at $755,987,318.

The Dragados Team’s proposal included a bored tunnel and construction will begin on Island 1 in the fall of 2017.  Total construction of the parallel tunnel at the Thimble Shoal Channel is expected to take approximately five years.

According to Commission Chairman Frederick Stant, “This has been a well-managed project with a thoroughly competitive procurement.  We look forward to working with the Dragados Team for the successful construction of this critical infrastructure.”

Dragados USA, Inc. is a wholly-owned subsidiary of Dragados, one of the construction arms of the ACS Group. Operating in 68 countries, ACS was ranked #1 on the 2015 ENR Top International Contractors List.

RELATED: Revised Bids Received for Thimble Shoal Tunnel

Dragados has built over 900 miles of tunnels; 5,300 miles of highways; and 1,500 bridges.  Dragados USA has worked, and is presently working, on major tunnel, infrastructure and dam construction projects, including the East Side Access Caverns and Tunnels in New York City; the I-595 Corridor Roadway Improvements Project in Broward County, Florida; the Portsmouth Bypass in Ohio; the SR99 Bored Tunnel Project in Seattle; and the Calaveras Dam in San Francisco, California.

Schiavone Construction, also a Dragados company, has major contracts in construction, repair, replacement and reconstruction of tunnels for rail and mass transit systems, including the East Side Access, Second Avenue Subway, and No. 7 Subway Extension projects in New York, as well as bridges and highways, deep foundations, treatment plants and marine work.

The Final Procurement Phase

On May 27, 2016, the Commission invited each of the three teams that had submitted fully compliant proposals by the original due date of April 29, 2016, to submit revised proposals for a re-scoped project.  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 for the project.

HNTB Named CM for Thimble Shoal TunnelThe re-scoping of the project was focused solely on the reduction of costs by reducing or eliminating non-critical elements of the project without compromising the technical safety factor of the design, customer safety and maintenance life cycle priorities that are specified in the technical requirements of the RFP documents.

The conceptual design for the project RFP initially included the widening of the man-made islands 250 ft to the west of the existing islands to provide physical space for either an immersed tunnel or bored tunnel to transition to the existing trestle alignment of the CBBT.

RELATED: HNTB Named CM for Thimble Shoal Tunnel

Jeff Holland, Executive Director of the CBBT, states that “The project was originally envisioned with a substantial expansion of the portal islands.  As such, the expanded southern island would have created space for the future public amenities at little additional cost.  When all of the teams competing for the project focused on reducing cost, it became apparent that island expansion could be very limited or non-existent.  As a result, the inclusion of the space sizing for the public amenities of a restaurant, retail shop and 200 additional parking spots that would otherwise require substantial island expansion became cost prohibitive and not necessary to meet the basic mission of the CBBT: providing the traveling public with a safe, cost effective, and unique driving experience across the scenic Chesapeake Bay. This scope change, combined with others, allowed the Commission to substantially reduce the cost of the project by nearly $260 million from the low price received during the first phase of design-build proposal prices.”

The fishing pier at Island 1 will be renovated during the construction project and will re-open to the public in 2022, upon completion of the project.

Tunnel Construction

The Dragados Team has proposed to construct a bored tunnel for the new Parallel Thimble Shoal Tunnel.  Construction will begin on Island 1 with the construction of a large pit.  The tunnel boring machine (TBM) will be delivered to the site in several large pieces and will be assembled in the bottom of the excavated pit.  After assembly of the TBM, construction of the tunnel will begin.

The TBM will excavate and build the tunnel as the machine progresses from Island 1 to Island 2.  As the machine excavates, the soil will be conveyed back to Island 1 for removal.  At the same time, new precast concrete tunnel segments will be delivered to the TBM.  The TBM will be equipped with automatic controls that will precisely place the precast concrete tunnel segments as the TBM progresses.  After the TBM reaches Island 2, the machine will be disassembled and removed from the site.  After the tunnel liner is installed, construction crews will install the final roadway, lighting, and mechanical systems.

RELATED: Final Segment Placed for Virginia’s Elizabeth River Tunnels

The public can learn more about this project design, construction, join Project Connect, and view a video of a TBM by visiting the CBBT project website.

Jeff Holland concludes, “While there are many entities and people to thank for the success of this project’s development, procurement and environmental assessment, the CBBT Commission especially acknowledges FHWA and the Commonwealth’s Secretary of Transportation Aubrey L. Layne Jr. and the Virginia P3 Office.”

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