Union Station is the busiest passenger transportation facility in Canada, serving approximately 250,000 passengers each day. By adding a second subway platform and expanding the concourse to include a single TTC fare-paid area and pedestrian by-pass routes, the TTC will reduce overcrowding and improve passenger circulation.

The Union Station Second Subway Platform and Concourse Improvements Project is one of Waterfront Toronto's (WT) priority projects. The Toronto Transit Commission is the proponent of this project and has managed the planning, design and now the construction of the project.