As an engineer for a municipality in British Columbia, you get some pretty funny requests for assistance. Assuming the lakes freeze up over the next month, Rossland is hosting the annual Canadian Western Regional Pond Hockey Championships in January. Several of the ponds are going to be man-made, but there are hopes of using some natural lakes for a traditional feel to the event as well.
But the question came up – when is it safe to walk, drive a skidoo, car or truck on the ice? Interestingly, this is something that has been studied in detail for the ice roads that exist in Northern Canada, and even some in Southern BC, such as the one on Lake Windamere, near Invamere.
So I pulled out the trusty North West Territories guide to Ice Road construction and maintenance (pdf) and read up on the methods and safety precautions they take to ensure these roads are able to be used for heavy vehicles. Now you may say, “But I walk on frozen ponds all the time, or, what about those guys who go out ice fishing, what’s the big deal?” Firstly, there is the continuous duty to ensure suitable levels of risk management are being undertaken on all projects that the City assist with. But secondly, it is important to know just how much weight can be put on a frozen lake of a given depth – considering that there will be players, spectators, it may be necessary to have vehicles clearing the snow off the ice, ambulance access may be required, and any number of other scenarios.
So the upshot is that there are tables of thickness that can be used as a preliminary guide, but it is important to observe the consistency of the ice, and understand that many different conditional factors can radically change the safety of the ice. The number s below are for moving loads, static loads must be treated carefully, as the ice can creep under a static load. Read the pdf for more information.
We’re looking foward to the pond hockey tournament in January, if you are out this way, come drop in for some hockey the way it used to be played!