Ottawa’s light rail tunnel will likely need to be shortened to deal with a deeper than expected bedrock, officials working on the project said Tuesday.
“The bedrock near the University of Ottawa is two to 10 metres deeper than anticipated and that’s why the team suggested shortening the tunnel and coming to the surface sooner,” said Gary Craig, the city’s chief of rail, engineering and construction. Craig and other officials at city hall presented an update on preliminary engineering work on the light rail project.
Craig said shortening the 3.2-kilometre tunnel by as much as 900 metres will save some of the projected $700-million cost of the tunnel. But Craig said those savings will likely be balanced out by increased costs in other parts of the tunnel.
Fault lines detected in the downtown core by the light rail team were anticipated and can be dealt with using standard engineering techniques, Craig said.
Spots where ground conditions differ from projections will be studied in phases two and three of the preliminary geotechnical survey, said John Jenson, director of the city’s rail implementation office. The second phase of the survey is set to go ahead in the spring of 2011 and updated results will be posted to the light rail project’s website, ottawalightrail.ca.