Snow-covered trucks have triggered the overheight warning monitors at the Squirrel Hill and Fort Pitt tunnels 35 times since last night, causing major traffic headaches.

PennDOT this morning issued an advisory asking tractor-trailer drivers to abide by a state law requiring all motorists to remove snow and ice from their vehicles before driving.

Sensors in place on the approaches to the tunnels are designed to detect overheight trucks and flash a warning to them.

When the overheight sensors are triggered, the red signals are activated at the entrance to the tunnels to prevent too-tall trucks from entering and causing damage. The trucks are ordered to turn around, PennDOT spokesman Jim Struzzi said. That can take several minutes, causing severe backups at peak times.

"It really caused some problems this morning at rush hour," Mr. Struzzi said.

Snow-covered trucks triggered the warning system 25 times last night and five times this morning at the inbound Squirrel Hill Tunnels and three times last night and twice this morning at the Fort Pitt Tunnels, he said.

"In addition, some trucks are still entering the tunnels (despite the red signals), causing the snow and ice to be pushed from the trucks onto other vehicles and the roadway creating extreme safety hazards," Mr. Struzzi said.

State law imposes fines of $200 to $1,000 if snow or ice dislodged from a vehicle causes a death or serious injury.

PennDOT said state police will be increasing enforcement in the tunnel areas to ensure drivers are complying with the law.

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