Testing conducted to assess whether the city's LRT system could withstand an Ottawa winter was mostly done through laboratory simulations and didn't involve driving the vehicles outside, the city says.

The winter-weather tests, administered in early 2017 inside the National Research Council's "climate chamber," simulated cold, wind, rain, snow and ice conditions and temperatures ranging from –38 C to 38 C, the city said in a summary of the test results posted on Wednesday's city council agenda.

The purpose was to determine whether the Alstom Citadis Spirit light rail vehicles could continue running and keep riders comfortable in a climate with extreme weather and temperature swings.

City officials said the vehicles passed most of the tests.

"The climatic testing of the Citadis Spirit LRV generally demonstrated that the vehicles can withstand Ottawa's most severe weather conditions and provide a safe and comfortable ride for customers," the summary said.

"Seeing that the majority of climatic tests passed without issues and a sound rationale explains each of the deviations, the overall climate comfort and climatic conditions test were considered as passed."

The testing method raises the question of whether the simulation was rigorous enough, as the Confederation Line experienced a litany of problems during its first winter in service.

From switch failures to sensors fooled by blowing snow to power losses, city transportation officials blamed weather for many of the issues which led to delays and replacement buses.

Rideau Transit Group (RTG), the corporate partnership that built the system, would not consent to release of the full results of the 39 tests. Councillors will be able to view the results in the city clerk's office.

The vehicles failed four tests mainly due to issues related to water leaks but the city says Alstom subsequently fixed those problems.

The only testing conducted outside was a series of supplemental tests conducted in OC Transpo's Belfast Yard which involved defrosting the front windshield and some temperature tests.