Canadian Consulting Engineer
Studies raise concerns over Champlain BridgeTransportation Transportation Infrastructure
Two consulting engineering reports are at the centre of public concerns around the state of Montreal's Champlain Bridge.
Two consulting engineering reports are at the centre of public concerns around the state of Montreal’s Champlain Bridge.
On July 13 the Federal Bridge Corporation published the second of two reports about the bridge, which was completed in 1962 but is now undergoing major repairs.
The first report, released already back on March 21, was written by Delcan. It was an assessment of the bridge’s structural health based on its condition in 2010. The study found several deficiencies “some of which are very significant,” and carrying risks “which cannot altogether be quantified.”
Measuring 6 kilometres, the bridge is one of the busiest in Canada. It consists of a steel cantilevered main span supporting an orthotropic steel deck. The remainder of the bridge is pre-stressed concrete beams supporting a pre-stressed concrete deck.
Entitled “The Future of the Champlain Bridge Crossing,” the Delcan report said that the bridge was not designed for current seismic load requirements, and therefore could not be considered a “lifeline” bridge.
The Delcan report also said that while the bridge’s operator – Jacques Cartier and Champlain Bridge Incorporated – was conducting a methodical program of rehabilitation, the post-tensioning approach was not a long-term solution.
The report found that some of the problems are because originally the bridge was not designed to be resistant to corrosion. In its initial years the bridge was not salted, so corrosion was not a major issue. However that changed “soon thereafter” and as a result “the bridge has now suffered some significant deterioration of the concrete and steel which comprise the bridge, particularly on the bridge approaches where both the superstructure and the substructures have been adversely affected.”
The report also found that maintaining the bridge for 15 years and then replacing it would cost around the same as maintaining the existing bridge for another 50 years. “This is an unusual finding in the context of a bridge in reasonable condition and it suggests that this bridge is in very much poorer condition than would be typical for bridges of its age and importance,” said the report. It also noted also that the 1962 superstructure design had been selected as the least expensive of 28 alternatives.
The other study about the bridge, which was a pre-feasibility study, was only just made published on July 13, although it too was written early this spring.
The authors of the pre-feasibility study were Consortium BCDE, which consists of BPR, CIMA+, Dessau and Egis. They were commissioned to look at possible replacements for the existing bridge and an adjacent ice control structure in the St. Lawrence.
Entitled “Pre-Feasibility Study of the Replacement of the Existing Champlain Bridge” dated March 31, 2011, the BCDE report recommended that any new crossings be made downstream of the existing bridge partly to minimize the impact on the Ile des Soeurs. The report summarized different possible bridge types, including prefabricated box girders (the cheapest), and a composite bridge with V-shaped piers (one of the most expensive.) The tunnel design alternatives presented include one that has two bored tubes with two superimposed levels, with an upper level in each tube dedicated to road traffic, and the lower level dedicated to public transit and safety evacuation.
The Champlain Bridge is one of the busiest in Canada, with 156,000 vehicle crossings per year in 2009. It spans the St. Lawrence Seaway between Montreal and the South Shore, landing on Nun’s Island, and connecting to the Bonaventure Expressway.
The Jacques Cartier and Champlain Bridges Incorporated (JCCBI) is a subsidiary of the Federal Bridge Corporation, which is a crown corporation that reports to Transport Canada.
Because there had been delays in releasing the pre-feasibility report, the media and the public questioned whether the federal government was concealing information. Bob Rae, interim Liberal Leader, has said he believes there were other studies on the bridge that the government is not releasing.
For photos of current rehabilitatioin work, click here.