The restoration of the train shed roof (the roof covering the passenger platforms and tracks) is the major component of the Union Station renewal project. The objective is to restore the east and west portions of the shed totalling 30,000 square metres (300,000 square feet) and to replace the central 5,000 square metres (50,000 square feet) of the train shed with a large glass atrium. The train shed is a designated heritage structure, so GO Transit worked with Parks Canada in the overall design, ensuring that the heritage character will be preserved.
The glass atrium will float over the tracks, providing daylight at platform level and a visual connection from the station to the waterfront. The view of the roof, which is visible from offices and other tall buildings in the area, will be improved by a green roof, and photovoltaics (solar cells) may also be added. These changes would help reduce the “heat island” effect that raises temperatures in urban areas, reduce the concentration of rainwater run-off, and generate electricity to offset the needs of the station.