Movement by rail has always been a significant mode of transferring people and products from one place to another and when the railroad came to Lambton County that certainly was no less true. Since rail travel was swiftly becoming the transportation mode of choice great advances were made in a relatively short span of time. Sarnia, Ontario and Port Huron, Michigan have the distinction of sharing the world’s first international submarine railroad tunnel. “Employing innovative construction methods, the tunnel was completed in a relatively short time, the two bores from opposite shores meeting only a fraction of an inch off center. First employing steam locomotive power, the tunnel was later wired for electric operation until the diesel retired it in the 1950s,” (Anderson, 8.)

The location of the tunnel between Sarnia and Port Huron was decided upon due to the geological makeup of the area. The tunnel was built in the blue clay above solid rock. The tunnelling shields were assembled on site, on either side of the river and lowered into the excavations prepared for them. Workers within the shelter of the shield dug out the clay and passed it back for crews to remove it to the surface. As the shields advanced follow up crews would line the tunnel with cast iron plate sections whose joints were calked and waterproofed. The average advance per day was ten feet. As crews from both sides of the river advanced towards each other no one knew for sure if both ends would meet in the middle. They did however, while only being off by a fraction of an inch. This is a marvel of technology by 21 st century standards but to think that this feat was completed in the 1890s is astounding. The tunnel’s chief engineer was Joseph Hobson who was well known at the time for his engineering accomplishments (Gerry Elder.)

The first St. Clair Rail Tunnel was built in 1890 and opened September 19, 1891.

Total length of the tunnel, portal to portal, 1837.3 metres (6028 feet).

At its lowest point the top of the tunnel is 40 feet below the surface of the river.

The cast iron lining is made up of 4000 rings of 13 segments plus a key piece at top with a total weight of 25 454 tonnes.

Total workforce was 600-700 workers whose average wages per hour were 17.5 cents for diggers, 15 cents for erectors and 12.5 cents for others. When men started working under air pressure, a bonus of one dollar per day was added (Elder.)

In 1993 construction began on the second St. Clair River Tunnel. The second tunnel became a necessity when double stack freight carriers came into standard use. The original tunnel was simply not built for trains and containers of such a large size.

Second one opened April 5, 1995

Total Length of the Tunnel: approximately 1868 metres (6130 feet)

Outside Diameter: 9.5 metres (31 feet, 2 inches)

Inside Diameter: 8.4 metres (27 feet, 6 inches)

River Depth: 35 feet

Tunnel Lining Segments:

Precast steel reinforced concrete rings: 1256

Each ring: 6 segments and a key, 1.5 metres wide (5 feet), 40 centimetres (16 inches) thick

Weight approximately 7 tonnes

Grand total: 8792 pieces

Unlike the tunnel constructed in the 1890s the one constructed in the 1990s was not dug by man but rather by a boring machine called Excalibore.

Excalibore was 9.5 metres (31 feet, 3 inches) in diameter. Its length was 98.2 metres (322 feet) and weighed 724 tonnes.

The cutting head: articulated design: movement of up to 1.8 degrees, 12 flood controlled doors, 200 spade type teeth, 53 back loading ripper teeth, 53 back loading twin disc cutters, powered by eight 300 horsepower motors, rotation speed of cutting head: min – 1.5 rpm to a max of 2.5 rpm.

Propulsion: total thrust 6000 tonnes

30 cylinders by 200 tonnes each