August 2001

Bridge Icing Accidents Eliminated in the First Year of System Operation

Accidents on an Ontario bridge prone to black ice formation were completely eliminated during the 2000-2001 winter. This dramatic improvement, from 14 icerelated

accidents the previous winter, can be attributed to the installation of the first automated anti-icing bridge spray system in Canada. The system, Fixed Anti-icing

Spray Technology (FAST) has the potential for widespread use at problem locations.

The bridge, a ramp at the Highway 401-416 interchange near Prescott, developed icing problems the first winter it was opened. Moisture from the nearby St. Lawrence

River condensing on the deck, bridge geometry, and the numerous freeze/thaw cycles that occur in the area, combined to create frequent icing conditions that crews

couldn’t accurately forecast. The Ministry of Transportation of Ontario, anxious to find a solution, approached Mark F. Pinet & Associates Limited of Ottawa.

Mark Pinet, President, Mark F. Pinet & Associates, noted “the solution we came up with was to link a Road Weather Installation System (RWIS), which monitored moisture, air temperature, humidity, precipitation and pavement conditions, to a system that can spray anti-icing chemicals on the deck surface.” When the RWIS determines that icing conditions have developed, a signal to spray is automatically generated, and if desired there

is no need for human intervention. “If we can have a system where the black ice doesn’t develop, that would be the goal across the province and we would have far

safer highways during the winter time,” said The Honourable, Brad Clark, Ontario’s Minister of Transportation.

Another benefit to the system is that smaller amounts of chemicals can be used due to the constant monitoring of deck conditions. The reduced impact on the concrete and steel in the bridge is expected to both lessen rehabilitation costs and extend structure life.

FAST could also reduce legal liability, if a May 2001 decision of the Ontario Court of Appeals is any indication. In that case, the province was found liable for a 1988 accident in which a driver lost control while crossing a bridge on Highway 401 and suffered severe

brain damage. Damages of $4 million were awarded after finding that road crews had not responded to weather reports calling for frost.

For more information on the FAST system, contact

Mark F. Pinet & Associates Limited at (613) 825-5716 or by email