Why bridges are better than culverts

Hey there, time traveller!
This article was published 28/12/2018 (390 days ago), so information in it may no longer be current.

Imagine that you are floating down the urban Seine River from the floodway to the Red River. You will encounter 20 river crossings on your 26-kilometre adventure.

Thirteen river crossings are bridges. The Seine has two train bridges, three vehicle bridges (Fermor, Royalwood, and Creek Bend), and eight pedestrian bridges.

Bridges are the best type of river crossing. They do not limit the amount of water the river can carry. They can often be built without disturbing the river so the impact on fish and habitat is minimal. The natural river bottom, banks, and riparian plants can be retained. Bridges do not block fish and other aquatic animals. Terrestrial animals like deer can travel safely under the bridge along the shore (Fermor Bridge). Unless the river is running high, you should be able to easily float beneath most Seine River bridges except the smaller footbridges (Niakwa Trail, Windsor Park and St. Boniface Golf Courses).

At the other seven river crossings, embankments were built (instead of bridges) to support roads or train tracks crossing the river. Culverts were installed for the river to pass through the embankments.

A culvert is a tunnel or pipe. If you float through a large culvert, you will see concrete or metal to your sides and overhead. Culverts with open bottoms are better than those with closed bottoms because they retain the natural stream substrate.

A culvert that spans the active channel will often allow fish and other aquatic species to pass through. If culverts are narrower than the natural channel, they constrict the flow of water. This increases its velocity. Depending on the length of the culvert and the velocity of the water, fish may be unable to swim through the culvert.

Unlike bridges, river crossings with embankments and culverts block the movement of terrestrial species. Deer, foxes, raccoons, coyotes, rabbits, and people travelling the river corridor will walk up the embankment and across the road or railway tracks rather than swimming through a culvert.

The province is planning upgrades to Highway 100 (South Perimeter). This presents an opportunity to replace the 65-year-old box culvert on the Seine with a new bridge to allow wildlife and people to move safely under the wider highway. The project also proposes two new crossings on the Seine.

Would you prefer bridges or culverts? Public open houses are planned for Jan. 14, 17, and 22.

Michele Kading is a community correspondent for St. Vital and the executive director of Save Our Seine.