The new Champlain Bridge corridor project in Montreal, Canada will cost up to $4.5 billion, and is planned for completion on December 1, 2018. But what’s wrong with the current bridge? Why was the decision made to build a new one, with such a large price tag?
Spark-Notes (Easy Read)
This section provides a quick, non-technical summary of this post. For more details, including some more technical information, continue to the following section.
- Current Champlain Bridge, open to traffic in 1962.
- Designed by engineers at SNC.
- Designated a life-line route off the island during emergencies.
- A 2011 report found that the main span was in good condition, but the concrete girders were deteriorating faster then expected.
- If one of these beams fails, the bridge could collapse.
If the new bridge is finished on time, experts predict that a total of $550 million will have been spent on repairs. In October 2017, experts announced that it would cost an additional $250 million to keep the current bridge in service until 2020.
As a result of this assessment, and after years of discussions, the government of Canada finally decided to proceed with construction of the new Champlain Bridge. Stay tuned for a future post on the construction of the New Champlain Bridge!
Detailed Notes (Technical)
This section provides more details and technical information, expanding on the points discussed in the spark-notes section.
Condition of the existing bridge
For years, experts were discussing potential options for repairing or replacing the existing bridge. However, the findings from the study conducted by the engineering firm Delcan (see full report) was the catalyst that started the process of designing and building the new bridge. The study was commissioned in August of 2010 to determine the current state of the Champlain Bridge. Although the bridge is considered a lifeline for the island of Montreal, it was found that the bridge would not be able to withstand extreme seismic events.
The steel main span superstructure was found to be in relatively good condition, but the prestressed concrete girders, used for the approach spans, exhibited significant deterioration from the salt water running off the bridge roadway. The condition of the steel reinforcement in these girders cannot be determined, due to the potential dangers of damaging the pre-stressed strands. However, there is evidence of damaged and broken strands inside the concrete. The report also found that failure of the edge girders could lead to the progressive collapse of the bridge.
These findings confirmed that critical repair work was needed on the existing bridge in order to maintain its safety in service. However, the cost to repair the bridge over the next 40 years was found to be equal to the cost to maintain the existing bridge for 15 years while building a new bridge. This point made it very clear to all parties involved that a new bridge was needed – and fast.
Repair work needed
At first glance, the current Champlain bridge looks like it is using every bridge rehabilitation technique ever invented. For civil engineering students at the city’s various universities, it would be a perfect case study, and an easy field trip.
Sensors have been placed across the length of the entire bridge, to monitor its behaviour and deflection during service. In addition, the following repair techniques have been applied:
- A total of 74 steel truss supports have been installed under concrete edge girders, found to be in critical condition.
- External post-tensioning applied longitudinally along the edge girders.
- External post-tensioning applied transversely along the pier caps.
- External fibre reinforced polymer (FRP) wrap applied applied to the exterior of many girders.
Assuming that the new bridge is delivered on schedule, the total repair bill is expected to reach $550 million (CBC). But with the majority of repairs completed on the existing bridge, and the new bridge planned for completion in December 2018, it seems that Montrealers can rest assured:
The life-line crossing across the Saint Lawrence – one of the busiest bridges in Canada – will continue to be a safe choice for everyone.
For more photos, visit: Existing Champlain Bridge Photo Album
For more information, see below resources:
https://www.bridgeweb.com/New-reports-highlight-latest-action-needed-at-Champlain-Bridge/3691
http://www.nrcresearchpress.com/doi/pdf/10.1139/l96-941
http://montrealgazette.com/news/local-news/holding-it-together-on-the-champlain-bridge
Great article, and a perfect restart of Structural Digest. Keep it up.
very good article and explanation.
thank you Rami