Over the top

Stand on the metre-thick ice of a frozen lake and you do not need to see or hear a vehicle to know one is nearby.

You feel it, or more accurately, you feel the wave it creates. A vehicle moving on ice actually pushes a wave of water causing the ice to flex. Yes, ice bends – but only so much before it breaks.

If a trucker overdrives the wave, the ice can snap with severe consequences. For safety, and to protect the road, the speed limit is between ten and 30km per hour and trucks are spaced apart, limiting ice blowouts along the shoreline where the frozen ice road meets a land portage.

To reduce speed even further, the design of the ice road includes S-curves at the portages; and for those not paying attention, security officers use traditional police radar guns to record speeds. To the uninitiated, the sound of this ice cracking is eerie, even unnerving. But for those hauling freight north from Yellowknife, Canada, to the diamond mines, these “bumps” in the road are reassuring.

It’s the ice slowly releasing the wave’s energy. Hearing these thuds, like a mallet striking the underside of the ice, means the surface below is sound…

Driving on thin ice