The Thorold Tunnel, located in in the city of Thorold, in the Niagara Region of Ontario, is an underwater tunnel, carrying Highway 58 underneath the Welland Canal. Built between 1965 and 1967, the tunnel is 840 metres in length. It consists of two separate tubes, each two lanes wide. The westbound side has a sidewalk for pedestrians.
It is one of three tunnels under the Welland Canal (the other two being Main Street Tunnel and Townline Tunnel in Welland), and the only one constructed after the waterway opened.
This tunnel also had its concrete poured during the winter months of the year, which led to over-expansion of the concrete, resulting in some cracks in the concrete. Extensive work has been done to correct this issue during the Summer months of the year, closing half the tunnel down, diverting traffic to the other tube, reducing traffic to one lane.
The tunnel was constructed in stages. The Canal section was constructed during the winter months when the Canal was drained. A trench was dug, and concrete sections shaped like tubes were poured to form the tunnel. During the summer months, the end sections of the tunnel were constructed, allowing shipping to continue. A sidewalk was built on the westbound side of the tunnel, allowing access to pedestrians through the tunnel.
The air in the tunnel is constantly monitored for carbon monoxide and, if needed, using an elaborate fan system, can be changed within 20 seconds. The lighting in the tunnel is controlled by photosensors that operate the lights in stages to provide light levels comparable to those outside the tunnel. This is to reduce the chances of being blinded by a dark tunnel, or emerging from a well-lit tunnel into the darkness of night. Traffic signals are mounted to the ceiling to control traffic during maintenance or emergency situations within the tunnel.
- Length – 840 metres (or .84 kilometres)
- Height – 4.5 metres
- Lanes – two westbound, two eastbound
- Speed – 80 km-h
- Roof thickness – 1.8 metres of reinforced concrete
- Wall thickness – 1.5 to 1.8 metres of reinforced concrete, covered with epoxy paint
- Lighting – 2,300 HPS lamps
- Traffic volume – 24,300 vehicles pass through the tunnel daily
Enjoy your trip!