Engineering students across the country are racing concrete toboggans in London this weekend

Concrete toboggans built by engineering students from across the country will race down a London ski hill this weekend as the Great Northern Concrete Toboggan Race returns to the city.

The annual competition brings together university teams who design and build concrete sleds capable of reaching speeds of up to 80 km/h before competing head-to-head on snow and ice.

“It's very intense. It's very exciting. It’s a huge rush,” said Jess Van Den Heuvel, co-chair of the race organizing committee and past racer.

The Great Northern Concrete Toboggan Race, or GNCTR, is Canada's oldest and largest student engineering competition and is now in its 52nd year.

This year’s event features 18 teams from across Canada and the United States, including students from 16 Canadian universities and one college.

Teams are judged on engineering design, safety, project management and race performance, with the main race taking place Saturday at Boler Mountain following a technical exhibition Friday at RBC Place.

The concrete toboggans that race down the hill are the result of months of design and hands-on construction by student teams, many of whom begin work well before the winter season.

“It’s a very long process,” said Jack Warden, co-chair of the race organizing committee. “Usually, teams are starting to design these all the way back in like the summer, and then transitioning to ordering all of their materials.”

Warden said most teams complete much of the work themselves, from fabricating parts to assembling the final sled.

While the sleds are built for speed, they are also subject to strict weight limits with a limit of 350 pounds.

“The heavier your toboggan is, generally, the faster it will pick up speed on the way down the hill," said Warden. "But there’s pretty severe deductions for exceeding the 350 pounds.”

That pressure often becomes clear during the technical exhibition, when teams weigh their sleds for inspection.

“Half of that will be teams getting weighed in, realising they’re just over the weight limit and desperately trying to drill holes wherever they can,” said Van Den Heuvel.

While the races may look like a straight sprint downhill, race day performance is only one part of how teams are scored.