According to research, the general guidelines to the safe ice thickness when driving on an ice road is:
- Snowmobile & ATVs: 5-7 inches
- Car & small pick-up’s: 8-12 inches
- Medium Trucks: 12-15 inches
Ice-roads are usually declared when the ice thickness exceeds 7.9 inches (20 cm).
The limitations therefore for ice road traffic would normally include a speed limit of 19 mph or 30km/h; sometimes less in certain areas.
Proceed with caution if your reading is at least 4 inches as 4 inches is the general safety depth for walking. Ice more than 5 inches thick is possible to hold a snowmobile or ATV and ice more than 8 inches thick is likely to support a small vehicle or pick-up truck.
For any large rigs, the ice needs to be at least 40+ inches. If your reading is less than 4 inches it is safer to keep off of the ice.
Below are more in-depth indicators as to the thickness that ice should be when driving an arrangement of different vehicles:
- 2 ½ ton truck – 8 inches
- 3 ½ ton truck – 9 inches
- 7-8 ton truck – 10 inches
- ATV/Snowmobile – 4 inches
Do You Need Special Tires To Drive On Ice?
Essentially, you would need good traction and therefore you would need good tires.
Always make sure that your tires are properly inflated and have plenty of treads left on them before you attempt to drive on an ice road.
If you drive on ice roads it would be recommended to switch to snow tires every winter.
Snow tires are made of softer tires than all-weather tires and therefore they have a better grip on the road. They are also mandatory in may countries like Norway and Sweden so be sure to check the rules before you drive there.
Over and above this, snow tires have specially designed tread patterns which allow for better reaction on ice and snow.
Snow chains can also be used and because they can be kept in your vehicle at all times, it becomes a lifesaver if you find yourself caught in a snow storm.
However, when using snow chains, you will not be able to drive faster than 48 kilometers per hour.
Vehicles that are four-wheel-drive (4WD) can hug icy roads better than a two-wheel-drive although even four-wheel-drive vehicles would need snow tires or snow chains to handle more extreme winter weather.
Often sand and salt are used together to improve the roads as they each provide a different function in improving traction.
Salt dissolves into the ice road and decreases the freezing temperature of the ice and sand provides a gritty surface for the tires to adhere to.
Tips For When Driving On Icy Roads
Driving on ice or snow is very intimidating and can be extremely dangerous.
So the recommendation is that people really should rather stay off of the roads unless it is completely necessary.
- Wear dry shoes when driving as a wet shoe could cause your foot to slip off the pedal.
- Pull away in second gear and very slowly lift your foot off the clutch to avoid a wheel-spin. Using high gears can reduce revs and increase traction.
- Uphill – Before heading up the hill ensure that there is nobody behind you and drive at a constant speed, avoiding having to change gear whilst you are on the hill.
- Downhill – Slow down before the hill. Use a low gear and try to avoid breaking.
- If you have to use your breaks, apply them very gently.
- If you do get stuck, straighten the steering wheel and clear the snow from the wheels. Put an old rug or sack in front of the driving wheels to give the tires some grip.
There is no difference between driving a manual car or an automatic car; all should drive cautiously and avoid braking harshly.
Harsh braking can cause the car to slip and slide on the ice and the driver can lose control.
Ice Road Truckers Ice Thickness
Generally, to support the heaviest rigs as with Ice Road Truckers would be at least 40+ inches. This occurs essentially from February and continues until April. The landscape of the trucker’s route is generally white, so they can become very weary.
At the end of the two-month season, the ice can thicken up to 60 inches.
The road closes because the snow melts on the land and turns the road to gumbo, not because the lakes can’t bear the weight.
With ice being at a depth of 16 inches, Sno-Cats are sent out to clear the insulating snow. The road is then flooded to create ice on the surface and help increase the depth.
At 29 inches the first lightly loaded transport trucks can head out.
The dipping of the mercury sustains the thickness of the ice and therefore truckers who are hauling 70-ton rigs are not afraid to drive on the ice. It is the warm temperatures that occur that lead to the melting of the ice.
Due to this, traffic becomes less and therefore it decreases the number of goods being hauled.
The most fragile area of the ice is on the shoreline, where it is warmest and thinnest. Sometimes, if the trucker has been driving too fast an axle will breakthrough and the driver will need to leap from the truck and wait with one of his convoys until the ice thickens again before he can properly lift the transport out.
Ice gains in the thickness of an inch every couple of days.
Once there is a minimum of 42 inches of ice measured in the center and at each edge of the 50-meter wide roadway, it can carry whatever the load trucks can haul.
Guidelines for Ice Road Truckers
- If you drive over ice that is just 36 inches with a massive truck, you will hear a sound much like the sound of shattering glass. The surface will likely give way and the trucker will have to jump to safety within seconds. The shock of freezing air and frigid water can trigger a fatal heart attack.
- The speed limit of 35km/h even down to 15 km/h is required in some areas when entering and leaving the portages between lakes to ensure that the truck’s weight does not cause waves under the surface. These waves can damage the road or dislodge the ice from the shoreline and create a hazard.
- No stopping or drinking on the ice – Concentrated weight and heat from a truck would damage the ice and therefore could cause it to no longer be able to support a 60-ton truckload.
- Trucks are to travel in convoys of three and four, spaced half a kilometer apart.
How to Check Ice Thickness
When trying to ascertain the thickness of the ice you need to make a hole in the ice and then insert a measuring tape into the hole.
Hook it onto the edge of the ice, then take the measurement.
Some ways of making the hole are:
- Cordless Drill and wood auger bit – using tape, mark an 18” wood auger bit at safe ice depths of a 4” 6” and 12” and cut vertical holes in the ice with a cordless drill. The flutes in the bit will force ice chips out of the hole. The markings on the bit will identify the depth you have drilled, upon hitting the water. A tape measure into the hole, hooked onto the underside of the ice will confirm the depth.
- Ice chisel or Spud – Stab the chisel into the ice, repeatedly until the hole is made. A tape measure into the hole, hooked onto the underside of the ice will confirm the depth.
- Chainsaw – Cut a 12-by-12 inch square into the ice. Once it is floating raise it or tilt it to take the measurement. Ensure the square goes back into the hole to re-freeze and also ensure to insert a stick to flag the hazard.
- Homemade test pole – a 60″ long hardwood dowel of 2″ diameters are ideal for a test poker stick. Pre-drill a 3/16″ pilot hole 4″ deep in one end. Add some PL premium adhesive into the hole and then insert a 10″ nail about 5 inches deep. Grind the head of the nail into a sharp point.
Whatever method you end up using, always ensure that you repeat it in more than one area of the ice as there is huge variability in just a few steps away.
Ideally, check the ice thickness every 150 feet.
The act of clearing snow quickly makes the ice thicker by exposing the road directly to sub-freezing air (temperatures as low as -50°C or -58°F).
The safest ice to even walk on is black ice or newly formed ice. Grey ice is deemed unsafe as it indicates the presence of water. If you are not sure, rather stay off the ice altogether.