The Welland By-pass, completed in 1973, was a massive construction project on the Welland Canal in Ontario, Canada. A new channel long was constructed, providing a shorter, more direct alignment between Port Robinson and Port Colborne and by-passing downtown Welland. The project helped improve navigation along the canal and alleviated problems the presence of a busy ship canal was causing in Welland. Background Although the city of Welland had originally grown around the canal, by the 1960s the constant interruptions in the flow of the vehicular and rail traffic through the city became bothersome. A single ship would hold up traffic for at least ten minutes as it travelled under a vertical lift bridge. In periods of heavy ship traffic, a bridge might stay raised for multiple ships to pass, and long lines of cars, trucks and buses could be delayed more than 30 minutes. Additionally, many railroad yards and lines originally built on Welland's outskirts now found themselves in the middle of a growing city; the heavily used rail lines from Toronto to Buffalo were suffering delays, as well. The old route, established in 1932 with the building of the fourth Welland Canal, was also inconvenient to the ships since it was twisting and narrow. The five vertical lift bridges and a railroad swing bridge, all within close distance of one another, made the manoeuvring tricky and the journey stressful. Captains complained of bulky buildings on the canal's edge blocking the line of sight. One of them commented, "The main thing every Lakes captain used to dread was Bridge 15 [built during the 3rd canal era, but in use until 1972], a railway bridge in the town of Welland with an abutment in the middle... I think every captain on the Lakes must have [scraped it] at one time or another." Construction The by-pass project was a massive undertaking: 16.2 km² (4,000 acres) of land was expropriated for the construction. Approximately 50 million cubic metres of material was excavated. The new channel is wide, as compared to the width of the old channel. The channel's minimum depth is . Two tunnels, the Main Street Tunnel and the Townline Tunnel, were constructed to allow vehicles and trains to pass beneath the canal. To complement this, an aqueduct, to convey the Welland River under the new canal alignment, was built. The aqueduct's design is what is known as a four-tube inverted-syphon