The downtown tunnel planned as part of Ottawa’s future light rail system could be shortened by almost one third, according to a geotechnical survey released last month.
Originally designed to run for 3.2 kilometres from about Bronson Avenue to Lees Avenue, the tunnel might need to be shortened by up to 900 metres due to unexpectedly deep bedrock, according to the report.
Tunnelling through the bedrock, the solid rock lying beneath soil, would require more complex methods in order to complete the tunnel.
David Jeanes, president of the sustainable transportation lobby group Transport Action, says that while he is not opposed to studying the tunnel as an option, the results of phase one suggest that a re-evaluation of the entire plan might be in order.
“We’re stuck with the highest-cost solution,” he says, “They should have considered a ‘plan B’.”
Jeanes and other critics suggest the city should consider a second plan, such as putting a surface-rail system through the downtown core along the same lines as the system in place in Calgary.
Ata Khan, a specialist in transportation systems and professor at Carleton University, says that while it would be cheaper, a surface track through the downtown area in Ottawa is just not feasible.
He says it would take time for drivers to adjust to sharing the roads with the trains which could potentially cause major traffic problems.
He also suggests the surface-rail option could lead to accidents when drivers do not pay sufficient attention to barriers announcing oncoming trains.
By building the tunnel the city would have complete control, ensuring the trains have the right of way, which would help the system to run smoothly and efficiently, according to Khan.
City engineers are still considering solutions to the unexpected soil conditions, including shortening the tunnel and relocating the University of Ottawa “Campus” stop above ground.
The first phase of the three-part geotechnical survey, released in December by Golder Associates, found a few minor issues with the planned route of the downtown tunnel.
Officials say that even unexpected results do not necessarily spell disaster for the light rail tunnel.
Khan says the changes the engineers have proposed so far should not seriously affect the final project.
“There is no problem putting the Campus station above ground from an infrastructure point of view,” he says. “The system should still work.”
While other issues have been highlighted, such as loose rock under the Rideau Centre and a fault line running under O’Connor Street, these are manageable problems that can be dealt with using regular engineering techniques, according to the report.
Kanata-area councillor Marianne Wilkinson, chair of the city’s transportation committee, said the subterranean conditions unearthed so far are manageable.
“The little fault line they found is not a huge problem,” she says. “They just have to make sure that they deal with it properly during construction.”
Wilkinson says that there is a whole series of options for creating the tunnel and that the preliminary results should not affect the project significantly as a whole.
The results of phase two of the testing are due to be released in the spring, while the results of the final phase will be issued in November of this year.
Although the price of the light rail project jumped to $2.1 billion in October 2009, $400 million more than the city’s December 2008 estimate, there has been no indication as of yet that the price of the project will be changing again.
Wilkinson stresses that city council will not know for sure what changes must be made, or how it will affect the cost of the project, until all the results of the testing are in.