User:NorthernRaven/Deh Cho Bridge

The Deh Cho Bridge, currently under construction since 2008, will be a 1.1 km bridge across a 1.6 km span of the Mackenzie River on Highway 3 near Fort Providence, NWT, Canada. Although difficulties have been encountered during construction, it is currently anticipated to be open to traffic in late 2011.

History
NWT Highway 1 (or the Yellowknife Highway) must cross over a kilometre of open water on the Mackenzie River south of Fort Providence, with no bridge at this location. Historically, a seasonal ferry service has been provided (roughly mid-May until December or January), with an ice road maintained across the frozen river from December to April. During the spring "breakup" season, due to hazards from floating or jammed ice there is a 3-4 week period (from mid-April to mid-May) between the closing of the ice road and the start of ferry service. No vehicles can cross during this period, and supplies for Yellowknife and other highway communities north of the river must either be relayed across by helicopter, sent by air freight, or wait until ferry operations begin. A similar but shorter "freezeup" period used to occur in December/January between the end of ferry operations and the opening of the ice road, but since the early 1980s ferry operations have generally been able to extend until the ice road is open.

This closing of the crossing creates added transportation inconveniences and costs for residents north of the river, especially for perishable items such as food. A bridge has been of interest since the highway was opened, but various proposals for a bridge had difficulty establishing financial feasibility given the limited traffic volumes and the estimated construction and maintenance costs involved.

Initial proposal and development
In 2002 the Fort Providence Combined Council Alliance (composed of the area's Dene, Metis and Hamlet leaders) indicated it would pursue a proposal to build a bridge, and a Memorandum of Intent was drafted between the Alliance and the GNWT. The Deh Cho Bridge Corporation (DCBC) was incorporated, and presented a proposal to the Government of the NWT to finance and build the bridge as a public-private partnership. The DCBC would arrange financing, construction and operation of the bridge, which would be leased back to the GNWT for a period of 35 years, in return for annual payments and the proceeds of a toll on commercial vehicle traffic crossing the bridge. After the lease period, ownership of the the bridge would revert to the GNWT.

A feasibility study was commissioned, traffic analysis done, and a cost-benefit analysis study based on this was undertaken for the GNWT during 2002-2003. Capital construction costs were estimated at $55 million.

The GNWT passed enabling legislation (the Deh Cho Bridge Act) in June 2003, allowing it to enter into concession agreements for a bridge. DCBC received $3 million in funding from the federal Indian and Northern Affairs Canada department in 2004, and initially hoped to complete agreements with the GNWT and begin construction in that year.

However, the bridge proposal required regulatory review from the Mackenzie Valley Environmental Impact Review Board, which was finalized in March 2005. Requirements for final engineering and financial plans further delayed a concession agreement with the GNWT.

By 2007, citing inflationary increases in infrastructure construction costs, the proposed capital costs had risen to $165 million. This necessitated similar scale increases in the proposed annual payments from the GNWT to the DCBC over the life of the agreement to keep the project financially viable.

Concession Agreement
After lengthy negotiation, in 2007 public statements by the GNWT and others indicated that final agreements were close with the DCBC. A ceremonial celebration occurred in Fort Providence in August 2007 to mark the decision to proceed.

On September 28, 2007, after lengthy negotiation, the GNWT entered into the Deh Cho Bridge Project Concession Agreement with the DCBC. Further amendments were made February 22, 2008, although the document was not made public until after that time.

Proposed tolls
The Concession Agreement includes provision for tolls for use of the bridge. Tolls will only be charged to commercial vehicles; private vehicle traffic will not pay any toll.

The toll rates are defined for three types of commercial vehicles based on the number of axles. A basic rate for "tractor-trains" of 7 axles or more is defined, with "tractor-trailers" of 4-6 axles paying 60% of this rate, and "straight trucks" with 2-3 axles paying 25%.

The formula for the rates is based on inflation adjustments on the completion of the bridge, but based on 2009 data the full Tractor-Train rate would be about $260.

Design
The original design was completed by JR Spronken and Associates Ltd. of Calgary in 2002. Following the GNWT's independent review, performed by its consultants BPTEC of Edmonton and T. Y. Lin International of San Francisco, recommendations for changes to the superstructure design were made. Infinity Engineering Group of Vancouver is carrying out the necessary redesign.

The superstructure is a two lane, nine-span composite steel truss bridge with a cable assisted main span of 190m. The approach spans are symmetrical about the centre of the bridge and have successive lengths of 90m, 112.5m, 112.5m and 112.5m. The total length of the bridge is 1,045m. The superstructure consists of two 4.5m deep Warren trusses with a transverse spacing of 7.32m and a 235mm thick precast composite deck. The truss members are built up I-sections. Two A-pylons, located at Pier IV South and Pier IV North, each support two cable planes. Each cable plane consists of six cables that are connected to the main truss through an outrigger system.

Construction
Actual construction began in June 2008, with an estimated opening date of late 2010. Work was completed on the approaches and support piers, although the final approved designs for the superstructure were not yet complete. The four piers on the south side were put in place in 2008, and three of the four northern piers during 2009.

Delay and redesign
During final approval of the bridge plans by the GNWT and its outside technical advisors, inadequacies relating to the design of the superstructure were discovered. A delay in the construction schedule to allow for investigation of design changes was announced, and the opening date pushed back by at least a year to late 2011.

General contractor terminated
As of December 30, 2009, Atcon's role as general contractor for bridge construction was terminated by the DCBC. It was announced that an agreement could not be reached on a price for the revised superstructure. The DCBC also bought out Atcon's equity position in the corporation, nominally $2 million (although it may not have been fully funded at the time).

Announcement of cost increase
On February 12, 2010, the GNWT announced that costs associated with the redesign and delay had increased the costs of the bridge by at least $15 million, to $182 million. The DCBC's project management was also replaced. The NWT Legislature was to be asked to approve $15 million in additional funding to cover the increased costs.