The electrical problem that halted two light rail trains New Year's Eve was caused by a buildup of dirt or grit on their roofs, according to the head of Ottawa's transit commission.

Rideau Transit Maintenance, the city's contractor, now has proper cleaning procedures in place for the accordion-like apparatus on the roofs of LRT trains, said Coun. Allan Hubley.

The apparatus connects the train to the electrical wires overhead that provide power.

'A little frustrating'

"[It's] a little frustrating that those procedures weren't in place ahead of time, but they're there now," said Hubley.

The first of the two trains lost power at Cyrville station at 5:02 p.m. Tuesday, just minutes after OC Transpo began offering free transit service for New Year's Eve.

A second train was immobilized at uOttawa station that same hour.

Hubley had no time to celebrate that evening as he, other city executives and Mayor Jim Watson dealt with the two troubled trains and figured out how to get people moving. The trains were stuck for hours while OC Transpo focused on getting riders onto backup buses.

No revellers should have been delayed by more than half an hour, Hubley added.

Kanata South Coun. Allan Hubley, the chair of the city's transit commission, said it was 'a little frustrating' that the problem cropped up on New Year's Eve, when transit was free. (Jean Delisle/CBC)

New problem

The dirty rooftop apparatus and its electrical connection is a new problem for Ottawa's LRT.

The LRT's on-board computer system, doors and track switches have been the problems most closely tracked in the months since the train's September launch.

During an update at transit commission on Dec. 18, transit staff reported fewer instances of each type of problem and said OC Transpo operators and Rideau Transit Group were getting quicker at resolving them.

"It's how fast we can deal with [problems] and fix them is what's important to me right now. We've got to get that system to a dependable state," said Hubley on Thursday.

The train has also been delayed in the past by cracks in the welding of the tracks.

In a statement, Rideau Transit Maintenance said it was investigating whether the presence of "salt mix mist and copper dust from the overhead wire" contributed to the train delays.

A team of engineers is investigating, they said.