The late-December ice storm that knocked out electrical power for 300,000 customers in Toronto once again raised the question that follows such events: what if all of the power lines in the city were buried? Roadbuilders asked a further question: what effect would burying all of Toronto’s electrical utilities have on road construction budgets?
About 11,000 kilometres of Toronto’s electrical utilities are already buried. Toronto Hydro CEO, Anthony Haines, provided a staggering cost estimate of between $14 and $15 billion to bury the city’s more than 15,000 kilometres of currently elevated electrical utilities.
Toronto Hydro spokesperson Tanya Bruckmueller points out that much of the budget would involve the construction costs of burying electrical lines under roads, the only available real estate in many neighbourhoods. If electrical utilities were buried, she says, future electrical line repair and maintenance would also involve increased road utility cuts. Currently, the city provides permits for an estimated 55,000 road cuts each year.
Mississauga fared considerably better than Toronto during the December ice storm, with a peak of 25,000 outages and with customer power restored far more quickly. That outcome was attributed, in part, to the fact that about two-thirds of the almost 3,400 kilometres of utility line managed by Enersource is already underground.
“However, it has no effect on road budgets,” says Karen Ras, director, corporate relations with Enersource. “In Mississauga almost all of the electrical lines are buried in grassed-over areas in boulevard spaces.”
Harry Orton, an independent hydro consultant based in Vancouver, says that the choice to bury electrical cables is largely based on policy, not cost, noting that in Denmark and other countries all electrical lines are now buried, including high-voltage transmission lines.
“You have to look at the lifetime cost of your choice, including road costs,” he says. “Sometimes the lifetime cost is one to one over 30 years.”
Orton recalls engineer Stuart Hicks convincing Vancouver to begin “undergrounding” its electrical utilities in 1969.
“It was a Cadillac system using ducts through which you drew the cables,” he says. “He was criticized severely at the time regarding the construction cost and the disruption to traffic and the public, but that gentleman had a lot of foresight and it paid off tremendously for BC Hydro. There are few road cuts or traffic problems—it’s all handled through manholes, and you can replace a length of line within a day.”
The City of Anaheim, Calif., is taking the long view at undergrounding its electrical utilities. The city stopped installing overhead lines in 1990 and began a project to incrementally bury its existing power lines along major road arteries over a 50-year span. Using that approach, utility customers are paying a premium of just four per cent on their bills to complete the project. With no available boulevard space, 90 per cent of electrical utilities must be buried under roadways.
Mark Vukojevic, Public Works city engineer and Fred Barvarz, Anaheim Public Utilities’ transmission and distribution manager, work closely to ensure that undergrounding doesn’t take a toll on roads or traffic.
“We’re working on a rolling five-year plan for underground conversion,” says Vukojevic. “We create a series of underground conversion districts one street at a time and give residents and businesses a lot of advance notice about what we’re doing.”
Wherever possible, the work is coordinated to align with sewer, water or other road work so that the projects can be combined, reducing construction and traffic impact.
“All other utilities, from telephone to data and cable television are mandated by the city to share the same trench,” says Barvarz. “They also share the road construction cost of the conversion.”
Construction crews complete road cuts in lengths of 100 to 200 feet per day. The cuts are typically backfilled by the end of the day, and paved by the next.
“In terms of repair and maintenance for the underground electric system, we rarely experience any digging or road cuts,” says Barvarz. “After the initial undergrounding, it doesn’t really affect the road construction budget.”
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