Thursday, April 30, 2009

Digging a tunnel: lessons from Edmonton

This was from the Ottawa Citizen towards the end of 2006:

Transportation expert John Bakker has a few words of advice about a downtown tunnel for Ottawa's proposed light-rail transit line: Don't do it.

"Going into tunnels is about 10 times as expensive as going on the surface because you have to relocate utilities," Mr Bakker said yesterday. "And you have to build stations, which are really extensive works, and very disruptive, too. Afterwards, you have high operating costs because of the ventilation systems."

Mr. Bakker, a civil engineer and professor emeritus at the University of Alberta, was part of a team that in 1968 recommended a downtown tunnel for Edmonton's light-rail system.

Bakker wrote a report about transit tunnels for lobby group Transport 2000 soon after the Citizen story went to print. In that report, which appeared in the December 2006 issue of Transport Action, Bakker pointed to a number of costs associated with tunnels that can add up quickly:

- relocation of utilities
- construction and maintenance of escalators and elevators, as well as stairs
- protection of entrances from "outside elements", requiring more space
- ventilation costs, which includes construction of reversible fans
- back-up power capability
- illumination of stations
- clean-up of graffiti