NEW YORK, Aug 18: Millions of American commuters went back to work on Monday, gingerly putting their faith in a transport system that had left hundreds of thousands stranded in last week’s dramatic power outage.

After a weekend spent re-booting the electricity grid that collapsed across eight northeastern US states and the Canadian province of Ontario, the beginning of the week offered the first real test of the still fragile network.

In New York City, where commuters had been forced to tramp through subway tunnels to safety when the blackout hit on Thursday afternoon, officials adopted a business-as-usual approach.

“The subways are working, the buses are working. It’s a Monday morning in New York; that’s what you’d expect,” Mayor Michael Bloomberg said.

“Probably everything will be fine for now, and we just have to make sure that we learn from this,” Bloomberg said.

But power giant Consolidated Edison still urged people to try to conserve energy, amid concerns that the spike in demand as New York went back to work could trigger fresh rolling blackouts.

Despite repeated public warnings about the dangers of eating spoiled food, the health department reported a significant increase in the number of people seeking treatment for diarrhea and related illnesses at city hospital emergency rooms.

“This underscores the need to make sure that food that spoiled during the power outage is not consumed and is thrown out if there is any doubt as to its safety,” said Health Commissioner Thomas Friedman.

Grocery stores and restaurants — from five-star eateries to humble pizza huts — were forced to throw out tonnes of rotting produce over the weekend and struggled to restock their fridges before Monday.

Most of Toronto, Canada’s financial hub and its largest city, returned to normal, but at a less frenetic pace, with fewer cars on the roads, the subway system less crowded and civil servants deemed nonessential staying home.

Ontario Premier Ernie Eves, who on Sunday urged residents and businesses to halve consumption, said the province was getting off on a “good foot” with demand at around 16,500 megawatts early on Monday, compared to the normal 22,000-24,000 megawatts.

“This isn’t just a one-day thing. It’s a week-long thing,” Eves said of conservation efforts needed by both industry and the public. “The challenge is still there.”

In the “Motor City” of Detroit, the freeways hummed with traffic on Monday, the auto plants ratcheted up production and water flowed freely.

“We look to be in good shape. We don’t see any problems meeting demand through the week,” said John Austerberry, spokesman for local utility Detroit Edison.

“There may be some challenges Wednesday and Thursday when the weather warms up again, but by then we should have more of our big generators on line.”

The Big Three automakers instructed blue-collar workers who work in assembly, stamping and components plants in the greater Detroit area to bring bottled water and their own packed lunches to work.

The city of Detroit extended a water boil advisory through Monday, until it can test water supplies and ensure they are fit for human consumption.

The warning was issued last week after authorities recorded a serious loss of water pressure.

The city of Cleveland, Ohio, lifted an advisory on boiling water late Sunday. But officials warned that beaches in the area were still unsafe for swimming because of untreated sewage pouring into Lake Erie.

The same was true in the New York region after sewage plants that failed during the blackout dumped huge amounts of raw sewage into city waterways.

US Energy Secretary Spencer Abraham promised Sunday a swift investigation into the precise cause of the largest power outage in US history.

“Today we’re sending teams of investigators into the field all over the regions that were affected. We’ve got hundreds of thousands of miles of transmission lines that need to be explored, substations,” Abraham said.

Three transmission lines in Ohio have emerged as an early focus of the inquiry.

Ohio-based FirstEnergy Corp. said the three lines near Cleveland had tripped out hours before the blackout swept across the northeastern seaboard.

FirstEnergy admitted that the alarm function of the computerized system for monitoring the transmission and generation system was not operating. —AFP