LRT wires 'melted' during January ice storm, transit commission hears

An accumulation of ice during a storm in early January triggered a series of failures that knockedOttawa's LRTsystem out of commission for days, the city's transit commission heard Thursday.

During the storm, which began on the evening of Jan. 4, ice began to form along the overhead cable system that powers the Confederation Line.

According to Richard Holder, the city's director of engineering services, the buildup wasparticularly heavy in a section near the Rideau River, betweenHurdman and uOttawa stations.

The Confederation Line remained partially closed from Jan. 5 to the evening of Jan. 10, while crews laboured tode-ice the cables and remove immobilized vehicles, including rescue trains.

Storm pushed limits of system

The LRT's overhead catenarysystem is designed to handle12.5 millimetres of ice accumulation. Onthe evening of Jan. 4, Environment Canada reported 4.3 millimetres of freezing rain per hour falling over Ottawa,Holder told commissioners.

"So we were already getting close to the threshold of our design," he said.

Even with the ice accumulation, the trains managed to keep moving until they reached the Rideau River microclimate, where the open water made for greater humidity and heavier ice buildup on the overhead wires.

That led tosignificant arcing, causing bright flashes and sparks where the trains'pantographs the roof-mounted apparatus that transmits power to the vehicle lost contact with the overhead wires,halting the trains on a stretch of trackbetween Lees and Hurdman stations.

When a recovery train was dispatched to help, its slow speed causedmore problems, Holder explained.

"The contact wires basically melted," he said,describing thesingle-strand wires that aresuspended from the catenary cable by droppers.

"Normally, when a vehicle is moving fast and we get arcing, the arcing ... is spread out over a larger area. With the vehicles basically stationary, that arcing all occurred in the same section, creating a huge amount of energy, a huge amount of heat generated, and the contact wire melted."

Two rescue vehicles eventually became stuck, a spokesperson for the city said.

On Jan. 6, crews were dispatched to remove the ice by hand along the entire middle section of the Confederation Line a distance of more than five kilometres.

Workers also had to replace the damaged wires and perform safety checks that took days,Holder said.

Heating wires, de-icingspray considered

Holder outlined several fixes that couldpotentially prevent ice accumulation from causing a similar multi-day failure.

A working group is looking atusing antifreeze, similar to steps taken by the Toronto Transit Commission (TTC). Other ideasinclude better monitoring of the equipment and procuring diesel vehicles to rescue immobilized trains.

"If we have issues with the power supply such as what occurredin early January, then we cannot use an electric vehicle for recovery," Holder said.

The group is also looking at the idea of equipping a maintenance vehicle with a specialice-breaking pantograph, as well as heating thecables to prevent ice from forming in vulnerable areassuch as near the Rideau River.

Since the Confederation Line opened three years ago, Holder saidit has experienced ice accumulation more than 50 times without incident.According to the working group's analysis, LRTtrains beginto break down when more than 6 or 7 millimetres of ice forms on the overhead wires.