Concrete Toboggans Teach Serious Engineering Lessons
John Hayes posted on March 07, 2013 |

There are lots of engineering competitions, but we’ve got a special place in our hearts for the concrete toboggan race. While not as inherently oxymoronic as the concrete canoe competition, it’s a great example of engineering reflecting the local geography – in this case the cold Canadian winter.

This year the competition was held in Vancouver BC, site of the 2010 winter Olympics.

As you would expect with an engineering competition, the Great Northern Concrete Toboggan Race features a number of design constraints including number of occupants and weight.

Toboggans are judged based on their concrete mix, their brake and steering designs and of course their performance on the hill.

There is also a (non-concrete) roll bar required. Watch the video at 6:00 to see why the roll-bar is essential. The rest of the racing in the video starts at 4:00. Enjoy.

This winter the competition winner was the 110 engineer squad from Western University, captained by Rob Volcko, a 4th year structural civil engineering student. Rob told us a few design considerations for building a winning sled:

The design
The rider configuration: Toboggans usually have 5 riders in a line like a bobsled or a 1-2-2 configuration with the person in the front steering. The Western team switched to the 1-2-2 design for 2013 to reduce weight shifting so the toboggan was easier to control.

Rob Volcko, Engineering student

Post-tensioned hollow box section concrete skis: The team designed a system for post-tensioning that included:

  • 2 pieces of high strength threaded steel rod
  • electrical conduits acting as ducts
  • 1/2" thick steel anchorage plates at both ends of the skis
  • hex nuts on both ends of the skis that could be tightened

The ski profile: All surfaces in contact with the snow have to be concrete, but flat surfaces don’t lend themselves well to steering. The Western toboggan skis featured inward grooves to reduce fishtailing and outward fins to cut into the snow to enhance steering.

The students draw the designs in traditional CAD packages and submit them along with a 100+ page technical report to the judging committee. And while experience can be passes along from team member to team member, no design reuse is allowed.

The importance of testing
In prior years the team was designing and constructing right up until race day. For the 2013 sled they completed construction in December, so they had time to test at a local ski hill. Not only did this allow the engineers to make adjustments, it also gave them confidence that their toboggan would actually make it down the hill.

The toboggans all weigh close to (but not more than) 300 lbs, so you can’t exactly ride up the chair lift with one, and pushing them uphill isn’t realistic either. However, they will fit in a pick-up truck so that’s how the Western team got theirs to the top of the hill.

Here are a few more links if you want to learn more:

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