Troublesome LRT restraining rails are on the move. What are they? - Action News
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Ottawa

Troublesome LRT restraining rails are on the move. What are they?

The safety rails that guard against derailments have to be moved by one to two millimetres before OC Transpo can relaunch service. Here's what they do and why Ottawa's are a problem.

Safety device is rubbing against wheels in a way that can damage train parts

Rails curve off into the distance, with orange on an inner rail
These restraining rails, which have been painted orange, need to be moved about 1 to 2 millimetres. (Michel Aspirot/CBC)

Work has begun to move the safety railsthat guard against derailmentsalong Ottawa's light rail transit line, according to OC Transpo.

The rails will move just one or two millimetres, ashiftthe light-rail transit system's builder and maintainer say should help ensure the heavy metal bars no longer damage parts of the train.

The move is yet another measure tomitigate against the risk of another system failure until a permanent fix is ready and a necessary fix before service can relaunch.

Restraining rails are a fixture on all sorts of rail infrastructure, and experts say the consistent contact that Rideau Transit Maintenance has been observingbetween the rails and the train wheelsis not meant to happen.

The issue is related to problemsthat caused the most recent damage to a bearing, andtwo earlier derailments.

What is a restraining rail?

Richard Holder, the city of Ottawa's director of engineering services, calls the rails a "passive safety device" located within curves. Theyrunparallel to the rail at a distance of about two inches.

"The only times that we would expect contact [between the rail and the back of the wheel] would be if there was a risk of derailment," he told reporters earlier this week.

"If a train, for whatever reason, was travelling around a corner and the outside wheels started to climb the outside rail, at that point there would be in contact with a restraining rail and a derailment would be prevented."
White-and-red light-rail vehicles sit inside a maintenance garage. Lots of criss-crossing tracks are visible.
Ottawa's light-rail vehicle fleet has been undergoing checks and maintenance since the trains were pulled out of service on July 17, 2023. (Michel Aspirot/CBC)

That climbing happens because of the force exerted on a train as it rounds a curve at high speed.

Rene Amilcar, the general manager for transit services, likens it to a driver accelerating a car around the corner and unbalancing the vehicle to the point that two of its wheels lift off the road.

"It's normal with your car," she said to media. "We want all the wheels to be on the rail ... the restraining rail will force the high rail, as we call it, to stay on the rail."

WATCH| This is what Ottawa's restraining rails look like

What is a restraining rail and what does it look like?

1 year ago
Duration 0:40
Ottawa officials and LRT stakeholders are looking into concerns with the train system's restraining rails. These rails have been doing something experts agree they should not: consistently rubbing against wheels.

Why are Ottawa's restraining rails a problem?

The problem with Ottawa's restraining rails is related to a broader issue with the system that has been widely reported on for years: tight curves in the system's east end.

The city highlighted eightproblematic areas, particularly those located near Hurdman station.

Some of these curves were identified by Mott MacDonald, a British firm hired by the city of Ottawa, as areas that have suffered fromwheel corrugation "a periodic wear of the rail surface into peaks and troughs" and rolling contact fatigue, wherethe rail head becomes crackeddue to "contact forces between the wheel and the rail."

Little orno corrugation was found in areas with straight track or shallow curves.

The 2022 report warned of premature deterioration of the light-rail vehicles and "increased maintenance."

Last year's public inquiry into various issues with the rail system also identified concerns over the "rail inclination" or degree of sloping at the curves.

When asked about that issue on Thursday, Holder said there's "no risk of derailment" because of the current wheel-rail interface.
A metal rail with ridges
This photograph, showing rail corrogation at a sharp curve west of Hurdman station, was included in an independent review of the LRT done by Mott MacDonald Canada Ltd. (Source: Mott MacDonald)

Why wasn't this contact issue identified before?

Contact with the restraining rail has been a known issue for a while, but was only identified as a pressing concern in a recent safety note from trainmaker Alstom and system builder Rideau Transit Group.

The city and RTG have said the issue is not a design defect, but a problem with maintenance.

"That is mainly due to the fact that we've been running the system for three years and all systems go through a process of wear, both of the wheels and of the rails," said Holder. "We're currently dealing with that new situation."

Nicholas Truchon, RTG's chief executive officer, said this will not become a recurring issue, because the last two weeks has helped "clarify" parameters that will allow maintenance crews to more effectively make adjustments.
Tracks go around a curve. In the distance, restraining rails, located within the curve are painted bright orange.
Restraining rails, painted orange at this curve west of Hurdman station, are designed to stop trains from derailing. (Jean-Sbastien Marier/Radio-Canada)

Why will it take ten days to move them?

The restraining rails are now being moved by amillimetre or two, a process that'sset to take a full ten days.

That meansteams will need to begin testing trains before work on the rails has been completed,ifthecity wants to meetits goal of reopening the Confederation Line to passengers on August 14.

"It's true that it seems relatively easy to move something one or two millimetres," said Enrique Martinez Asensio, RTM general manager. "But the reality is that the restraining rail is a very heavy steel profile that is bolted to the frame components of the track."

Specialized machines are required and crews need to be trained, he said.

"It's just a few millimetres, but we are talking about a lot of work."
An overhead view of train tracks in summer
An inquiry into Ottawa's problem-ridden light-rail transit system suggested it might be necessary to relay the track around the sharpest curves. (Michel Aspirot/CBC)