The tunnel is long and made up of six precast concrete sections (length: ; height: ; width: ). The sections were floated into position by barge and then sunk into a shallow trench that had been dug into the loose sand and silt of the river bed. The trench and tunnel sections were then covered over with a protective layer of rock— stones filled out on each side, plus a bed of stones on top. A structure located at each end of the tunnel houses the main ventilation and pumping equipment. Concrete retaining walls make up the approaches, which extend out about from the ventilation buildings. At its lowest point the roadway is about below sea level, making it the lowest section of roadway in Canada. The Fraser River flows into the Strait of Georgia about downstream from the tunnel.