The unspoken rule that governs behaviour on an escalator - stand on the right, walk on the left - is considered by many a measure of urban civilization.
Officially, though, it is a safety hazard.
It may come as a surprise that this long-standing accommodation between the hurried and the not-so-hurried in malls and subway stations runs counter to the advice of safety officials and the escalator industry.
No one, they say, should ever try to walk on an escalator.
In fact, the Toronto Transit Commission - the country's single largest escalator owner, with 294 - has removed all of the signs from its escalators that used to read: "Stand right, walk left."
Dexter Collins, the TTC's acting superintendent of elevating devices, said the decals were originally installed years ago at the busiest subway stations, Yonge-Bloor and St. George, where herds of rush-hour passengers change trains, taking escalators from platform to platform. Over the decades, the stickers migrated to all escalators across the system.
Then some employees of the provincial Technical Standards & Safety Authority, the agency that regulates and inspects escalators, noticed the decals at Islington Station - near the TSSA's headquarters - and brought them up in one of their regular meetings with the transit agency.
The TSSA, Mr. Collins said, recommended the signs' removal because they appeared to condone people walking on the escalators.
"I said, 'No problem,' I've never been big on that idea anyway," Mr. Collins said. "The intent is for the escalator to carry the people up the escalator. If they are capable of walking, they should be utilizing the stairs."
One province appears to be standing behind the escalator tradition, however. Kari-Ann Kuperis, a spokeswoman for Alberta's Ministry of Municipal Affairs and Housing, which oversees the provincial agency that regulates escalators, said "Stand right, walk left" decals are common in Alberta, and there are no plans to stop the practice.
Officials in Toronto acknowledge that walking on the left has become part of the culture and that they are powerless to control those who tempt fate and insist on walking up escalators. No one will be arrested in mid-stride. But both agencies say at the very least, the TTC should not appear to be condoning it.
Mr. Collins said 138 people were injured on TTC escalators last year, most often because of a fall. The majority, he says, are elderly people - a growing group on the system - who get knocked over by an impatient escalator-walker.
"We have some young whippersnapper whizzing by, nudging them because he's got some place to go or something to do," Mr. Collins said. "It seems to be the elderly who are paying for it."
TSSA spokeswoman Bernadette Celis said there was no "formal safety requirement or regulation" banning the "Stand right, walk left" decals, and that her agency's principal mandate is the proper maintenance and mechanical safety features on escalators.
"But from our perspective, we always promote that any kind of movement on an escalator is discouraged," she said.
The industry-funded Elevator Escalator Safety Foundation of Canada, a wing of the U.S. group based in Mobile, Ala., distributes safety materials, mostly aimed at children. They also agree that walking up an escalator is a bad idea, and say escalator-education campaigns are being updated to emphasize it.
"Any time you start moving, it adds potential for an accident," spokeswoman Leslie Schraeder said. "It's definitely the foundation's advice with escalators to step on carefully, hold the handrail, ride all the way to the top, and then step off."
She added that you shouldn't even walk on a deactivated escalator, as the stairs are taller than standard stair height, putting you at risk of tripping. As for "Stand right, walk left," it is the official safe advice for that horizontal cousin of the escalator, the moving walkway, she said.
Last November - after the TTC had already agreed to remove its decals - an accident on a GO Transit escalator at Union Station sent six people to hospital, one with very serious injuries. Witnesses said the device appeared to suddenly go into overdrive, speeding up and piling people on top of one another. The TSSA says it is still investigating the incident.
Every few years, news reports surface of catastrophic-sounding escalator accidents. Last year, after a handful of escalator incidents involving plastic clogs similar to those marketed by Crocs Inc., the company issued a statement insisting its footwear was safe. In 2004, 16 Montreal high-school students were sent to hospital after an escalator stopped suddenly.
By the numbers
Number of TTC riders injured on escalators last year
Number needing a trip to hospital
Number injured on stairs
Estimated number of escalator riders daily in North America
Number of escalator accidents in Ontario in 2005
Number of injuries considered serious
Fun escalator facts
World's first escalator: Coney Island, N.Y., 1894
Canada's first escalator: Eaton's department store, Toronto, 1904
Canada's longest escalator: York Mills subway station, 148 steps
Sources: Technical Standards and Safety Authority, The Globe and Mail