The bridge partially collapsed after a dump truck with its box raised slammed into it, causing long lines of traffic late into the evening.
Some cars stranded at the scene of the collision ran out of gas or drained their batteries, waiting for the scene to clear. Authorities handed out emergency blankets.
No one was seriously injured.
A woman who was driving behind the truck before the collision suffered minor injuries in the collapse, according to Quebec provincial police. The driver of the truck was taken to hospital to be treated for shock.
The highway is a major artery for thousands of drivers on the South Shore.
Collision specialists, as well as engineers and medical personnel, were on the scene late into the night assessing the damage, said Quebec provincial police spokesman Sgt. Claude Denis.
"When the collision happened, we were under obligation to stop traffic in both directions for the security of the population," Denis told CBC's Daybreak Montreal.
Denis said police have met with the driver involved in the accident, but he wouldn't disclose what he told investigators about why the truck's back was propped up while on the highway.
Denis said a similar accident occurred a few weeks ago in the Gatineau area. The driver in that case died, he said.
The footbridge in Longueuil links Marie-Victorin Park and Lemoyne Park. The collision happened near Normandie Street.
Longueuil police were called to the scene at 7:48 p.m. Tuesday.
The footbridge was destroyed after it was determined that the remaining structure wasn't solid.
Crews began tearing it down at about 3 a.m. this morning. The operation took about 30 minutes.
The mayor of Longueuil, Caroline St-Hilaire, said she's working with teams on-site to oversee the city's response.
Eyewitness Alain Collin said the truck was heading west carrying snow when it hit the overpass.Suggest a correction