Safety Guidelines For Ice Operations
General Ice Safety
- Documented ice thickness measurements must be obtained prior to any work starting on ice covered water bodies.
- The thickness of white ice over blue ice shall be recorded from each test hole.
- The load bearing capacity of the test area can be determined using your collected data with an approved ice capacity guideline for your area.
- Ice thickness cannot be taken for granted while testing. Many factors can affect ice thickness such as the natural freezing process (bays and shallow areas may freeze a number of days prior to the larger and deeper lake areas), currents by wind forced in narrow or shallow lake locations.
- Extreme caution must be taken when testing very thin ice crossings.
- Approved floatation gear is recommended on all test team and a recovered line on thin ice is essential.
- Team members should have a recovery plan in case a worker breaks through the ice.
The load bearing capacity depends on:
- Quality of the ice
- Blue ice is the densest, heaviest and the strongest
- White ice is lighter due to a higher air/water ratio yielding less overall strength.
- Thickness of the ice
- The thickness of blue and white ice must be considered in capacity calculations.
- Temperature of the ice
- Very cold ice can be very brittle where as warmer ice surfaces have more elastic properties.
- Larger ice crossings may experience noticeable cracking caused by internal stresses due to temperature driven expansion and contraction co-efficient.
- Speed must be regulated to minimize ice road damage.
- Hanging ice
- As water levels recede on lakes, ice may hang up on shoreline approaches. These areas have little capacity to support any weight.
Bearing Capacity of Freshwater Ice
The most accepted ice capacity guideline used in Canada, developed by Dr. Lorne Gold of the National Research Council of Canada. Dr. Gold dedicated most of his professional career to ice related engineering studies.
Ice Capacity Using the Gold Formula
P= allowable load capacity of the ice in kilograms.
H= Blue or natural ice thickness in centimeters
W= White ice (flood ice) thickness in centimeters
For solid blue ice:
P= 7.03 X H2
For blue and white ice combined:
P= 7.03 X (H + 1/2W)2
|2 = ||28|
|4 = ||112|
|6 = ||253|
|8 = ||450|
|10 = ||703|
|12 = ||1,012|
|14 = ||1,378|
|16 = ||1,780|
|18 = ||2,278|
|20 = ||2,812|
|22 = ||3,403|
|24 = ||4,049|
|26 = ||4,752|
|28 = ||5,512|
|30 = ||6,327|
|32 = ||7,199|
|34 = ||8,127|
|36 = ||9,111|
|38 = ||10,151|
|40 = ||11,248|
|42 = ||12,401|
|44 = ||13,610|
|46 = ||14,876|
|48 = ||16,197|
|50 = ||17,575|
|52 = ||19,000|
|54 = ||20,499|
|56 = ||22,046|
|58 = ||23,649|
|60 = ||25,308|
|62 = ||27,023|
|64 = ||28,795|
|66 = ||30,623|
|68 = ||32,507|
|70 = ||34,447|
|72 = ||36,443|
|74 = ||38,496|
|76 = ||40,605|
|78 = ||42,771|
|80 = ||44,992|
|82 = ||47,270|
|84 = ||49,604|
|86 = ||51,994|
|88 = ||54,440|
|90 = ||56,943|
|92 = ||59,502|
|94 = ||62,117|
|96 = ||64,788|
|98 = ||67,516|
|100 = ||70,300|
Ice Road Opening
- Snow ploughing operations can commence once the ice crossing has been marked out, tested and a determination made that the machinery used can be supported on worked area.
- To facilitate the natural ice thickening process the snow can be removed or if necessary compacted on the roadway.
- Windrows of snow placed on the roads edge often creak or deform the ice and sink.
- Avoid travelling near the snow windrow areas.
- The cold surface air temperature will now penetrate down through the ice to promote freezing.
Ice Road Hazards
- Extreme caution must be used around pressure ridges or open live cracks.
- These areas can be bridged or the road rerouted to a more favourable area.
- Slush is a result of the weight of snow covered exceeding the bearing capacity of the ice cover. As the ice gradually sinks, water flows up into the snow cover, which stops or slows the ice thickening process.
- Slush areas can be different difficult to plough off. Operators often run through these areas with a suitable machine to compact the snow and open up the wet areas to allow freezing.
- Slush covered areas will always have holes in the ice where the water has risen through. These holes can vary in size from a few inches to a few feet in diameter; the ice may be slightly weaker around these open areas.
- Operators should be aware that a break through could occur while working on open ice roads.
- Machines with cabs should have working escape hatches.
- Flotation/survival suit may be worn.
- Avoid the use of seat belts.
- Operators working in pairs will be able to offer assistance should a break through occur.
- Have a rescue plan ready.
- In most cases removing the snow from the ice surface will allow natural freezing to thicken the ice to a sufficient depth to support transportation equipment.
- Moving water or warm temperatures can slow or stop the natural thickening process.
- Flooding can be an option, which will allow the ice to form on the topside rather than the bottom of the road.
- Water is typically pumped on the ice in 1-2 inch lifts. Then allowed to freeze prior to re flooding.
Ice Road Operation
All ice crossings should be regulated to maximize the life of the road.
- Gross vehicles weight limits shall not exceed the safe loading capacity of the ice crossing. A moving vehicle will deflect the ice to a point where a hydrodynamic wave is generated.
- Speed will accelerate the stresses from the ice deflecting to a point where the ice may fail.
- Extreme caution must be used when large loads approach a very gradually rising shoreline.
- Large ice road operators will have different speed limits for crossing lakes based on ice thickness, ice quality and the lake bottom profile.
- A smaller lake and river crossing generally used 15 kilometres per hour as a speed guideline.
- Ice roads in general as seen from the topside are a maze of intersecting cracks induced by stresses of natural ice development (wind, temperature, cycles and moving loads).
- Safety guidelines have factored in the normal dry crack nature of the ice covers.
- Excessive new crack development, wet cracks, live cracks may require weight reductions, detours, or re flooding to stabilize the area.
Spring Ice Deterioration
- Warm temperatures will decay the ice, reducing its ability to support normal weights.
- Rays of sun penetrating bare blue ice will rapidly show deterioration.
- On going auger testing will determine if the ice is deteriorating to a point where load reductions are recommended.
Ice Safety Resources
Ice engineering and safety information can be found at:
- National Research Council of Canada
- Provincial Department of Highways Department
- US Army Cold Regions Research and Engineering Laboratory, Hanover New Hampshire U.S.A.
The information provided on this web site is only intended to be a general summary of information and bring awareness to the viewers of the need for safety while working on ice covers. The viewed information is not intended to take the place of Federal, Provincial, State or municipal written law or regulations of company work place safety guidelines. Always consult with your local authorities when working on ice covers. Big Ice and Ross Ind. will not be held responsible for any accidents, death, equipment loss or damage to do with, and not limited to : Ice thickness, Ice flooding procedures, Ice maintenance.