A buildup of ice during an early January storm triggered a series of outages that left Ottawa’s LRT system inoperative for days, the city’s transit commission heard Thursday.
During the storm, which began on the evening of January 4, ice formed along the overhead wire system that supplies power to the Confederation Line.
According to Richard Holder, the city’s director of engineering services, the buildup was particularly heavy on a section near the Rideau River between Hurdman and uOttawa stations.
The Confederation Line remained partially closed from January 5 through the evening of January 10 while crews worked to de-ice cables and remove immobilized vehicles, including rescue trains.
Storm has exceeded the limits of the system
The catenary system of the LRT is designed for an ice accumulation of 12.5 mm. On the evening of Jan. 4, Environment Canada reported 1.7 inches (4.3 millimeters) per hour of freezing rain falling over Ottawa, Holder told commissioners.
“So we were already approaching the threshold of our design,” he said.
Despite the ice accumulation, the trains managed to keep going until they reached the microclimate of the Rideau River, where the open water made for more moisture – and more ice build-up on the overhead wires.
This resulted in significant arcing, causing bright flashes and sparks where the trains’ pantographs – the roof-mounted device that transmits electricity to the vehicle – lost contact with the overhead wires and the trains continued on a section of track between Lees and Lees stations Hurdman stopped.
When a recovery train was sent to help, its slow speed caused further problems, Holder explained.
“The contact wires practically melted,” he says, describing the individual wires that are hung up on the catenary cable with droppers.
“Typically when a vehicle is moving fast and we get arcing, the arcing is … spread out over a larger area. When the vehicles are basically stationary, this arcing all occurred in the same section and generated a huge amount of energy, a great heat build-up and the contact wire melted.”
Two emergency vehicles eventually got stuck, a city spokesman said.
On January 6, crews were dispatched to manually clear the ice along the entire middle section of the Confederation Line — a distance of more than three miles.
Workers also had to replace the damaged cables and perform safety checks that took days, Holder said.
Heating wires, de-icing spray taken into account
Holder outlined several fixes that could potentially prevent an ice buildup from causing a similar multi-day outage.
A working group is addressing antifreeze use, similar to steps taken by the Toronto Transit Commission (TTC). Other ideas include better monitoring of equipment and procurement of diesel vehicles to rescue stranded trains.
“If we have power problems like the ones we experienced in early January, we can’t use an electric vehicle for recovery,” Holder said.
The group is also exploring the idea of fitting a maintenance vehicle with a special ice-breaking pantograph and heating the cables to prevent ice from forming in vulnerable areas like near the Rideau River.
Since the Confederation Line opened three years ago, Holder said there have been more than 50 incidents of ice accumulation. According to the working group’s analysis, LRT trains start to break down when more than 6 or 7 millimeters of ice forms on the overhead wires.
