For more than 150 years, the waters of the St. Lawrence River have beat against the limestone supports of the Victoria Bridge, and for just as long, trains have carried passengers and goods to and from Montreal.

While the other bridges that link Montreal to the South Shore are in constant need of repair - the Mercier Bridge is undergoing major renovations, while the Champlain Bridge may need to be replaced - the Victoria Bridge was built strong to last long.

The construction of the bridge began in 1864 when more than 3,000 workers, mostly Irish, began constructing the span for the Grand Trunk Railway. They laboured to build supports and hoist wrought iron into place for the tube that would surround the single train track.

The stone for the supports came from Pointe Claire, while the remainder of the materials arrived from the U.K.

"The tubular bridge was wrought iron and they brought that all over from England like a Meccano set," said Concordia mechanical engineering professor Hugh McQueen, describing piecemeal model construction sets.

Five years later, in 1859, the Victoria Bridge was finished, and the first passenger train rolled across it on Dec. 17 of that year.

At 2.7 kilometres, it was the longest bridge in the world at the time. It was then - and still is - solidly built.

"People didn't understand the strength of the metals back at that period and so they used a very high safety factor. This means that the bridge is much stronger than one imagines," said McQueen.

By the 1890s, the Grand Trunk needed to expand the bridge. Over a two-year period, workers installed trusses over the tube, and built a second track and two roadways cantilevered out from the bridge to accommodate pedestrians and carts. Without disrupting train traffic, they dismantled the tube and re-christened the bridge the Victoria Jubilee in honour of Queen Victoria's 60-year reign.

While there have been a number of changes over the years, including a new configuration when the St. Lawrence Seaway was built, the Victoria Bridge continues to serve the same purpose it always has.

"The Victoria Bridge is still extremely important for CN. It's a vital infrastructure for us because it's the link between eastern Canada, western Canada and the United States," explained Julie Senecal of CN Railway.

The bridge doesn't need corrosive salt during the winter and with regular maintenance that's carried out by CN, there's no reason the Victoria won't last decades longer.