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Project spotlight: Traction power substation installation

Image - Project spotlight: Traction power substation installation

What moves you? Well, if you asked a train on O-Train Line 1 it would say electricity.

Line 1 trains currently travel between Tunney’s Pasture and Blair stations drawing power from overhead wires known as the Overhead Catenary System (OCS). These wires draw their energy from a Traction Power Substation (TPSS) which plays a critical role in providing our vehicles with power.

In the future, you’ll be able to travel emission free from Moodie Drive and Algonquin College in the west, through downtown to Trim Road in the east. 

Let’s catch up on how we’re charging ahead with Traction Power Substation installation on the O-Train East and West extensions.

What’s a Traction Power Substation (TPSS)?

The TPSS transforms incoming power from an electricity provider (such as Hydro Ottawa or Hydro One) to the required voltage for the operation of the O-Train system. Typically, incoming voltages to TPSS in Ottawa are 13.2kV or 27kV (alternating current). They are a standard component of light rail systems across Canada.

On Line 1, TPSSs can be found strategically located across the system. You may recognize them adjacent to the tracks in various areas near stations. They look similar to a shipping container and are approximately 5 metres wide, 18.5 metres long, and 4 metres high on average. 

There will be eight TPSSs installed in the west and five in the east.

TPSS on road by O-Train West Extension

TPSS stored nearby the O-Train West Extension ahead of installation.

How are they delivered to Ottawa?

The TPSS are built in Edmonton and must travel to Ottawa by truck. Because of the width and size of the TPSS, the route for delivery needs to be carefully planned to allow the large load trucks to manoeuvre from one province to another. Considerations such as highway width, construction activities, and more, were taken while planning. Once the TPSS arrives, road closures are put into place to allow for the large trucks to make a safe deliver to the sites.

Watch the delivery to Convent Glen Station

TPSS on large transport truck

TPSS on a truck preparing to travel to Ottawa.


Before the TPSS get delivered, crews prepare the future site for installation. This includes utility work, pouring a concrete slab to anchor the TPSS and preparing the connections to the OCS. Once installed, the TPSS will be energized by Hydro Ottawa and connected to the OCS wires.

All five TPSS have already been delivered and installed on the O-Train East Extension.  The remaining will continue to be delivered through construction in the west. In some cases, the TPSS is built on site (known as stick-built) for a variety of reasons. Standard TPSS installations are prefabricated and delivered, a process done at most sites along the O-Train extensions. The TPSS location is selected in the vicinity from where required power needs to be drawn for that segment of the alignment. However, real estate availability, environmental issues, architectural design input, public and community feedback are a few of the general factors considered when selecting a site. Any of these factors may influence the decision to build the TPSS at the site rather than bring in a preassembled unit. Lincoln Fields and Sherbourne stations are the only two built on-site.

For more information on the O-Train Extension project, please visit the O-Train Extension website, follow OC Transpo on Facebook, Twitter, and Instagram, and sign up for the LRT newsletter.