Short answer: yes.
(And now the long answer…)
Before LRT, and we relied only on buses, there was a hard limit on how much service OC Transpo could provide and it was quickly becoming not enough. According to the agency’s website, only about 180 buses can travel through downtown every hour — there simply isn’t enough room for more. Transit ridership was about 9,500 to 10,000 people per hour, per direction during peak times.
Here’s some information from OC Transpo about how much Line 1 can carry now:
“The O-Train Confederation Line has a planned peak capacity of 10,700 passengers per hour in each direction, with the potential to grow to over 18,000 passengers per hour in each direction by 2031 and ultimately 24,000 passengers per hour in each direction … Each two-car train is 98 metres long and has the capacity to carry 600 passengers.”
So at present day, there is a small surplus of space for rush hour. Over time, the system is scalable. In fact, back when builders were bidding on the contract to build the line, they were required to explain how they would build a scalable system. The Rideau Transit Group, which won the contract and built the line, explained in a 2013 document (emphasis mine):
“The RTG proposal provides this capacity by providing a two-vehicle, 98-metre long train whose doors are accessible within the 90-metre long surface platforms. Once ridership rises above the 2031 level, the surface platforms can be easily lengthened at the surface stations to accommodate a variety of future operating scenarios and train lengths. The expandable platforms at surface stations can support a variety of possible approaches to adding long-term capacity including the possibility of future orders for longer vehicles combined into longer trains. All vertical circulation elements within stations have been sized for the ultimate capacity of the system. The three downtown underground stations are designed from opening day with a 120 metre platform to avoid any potential for costly excavation in the future. Public and emergency circulation elements have also been sized for these ultimate ridership volumes.”
So the subway stations are already designed for the ultimate capacity while the surface station platforms can be lengthened when required to meet growing ridership. In the nearer-term, additional train modules can be added and arrival frequencies increased to expand capacity without needing construction work. Someday we may need more capacity, and I suspect we’ll then be in a similar position as Toronto is now in seeking to build a relief line.