Why is working on ice a hazard?
Falling through ice can result in injuries from the fall, hypothermia, or drowning. Common hazards include:
This document covers general considerations when working on or near ice, for example, when driving on an ice road. For more detailed information about working on ice, see the resources at the end of the document. For information about working in cold temperatures, please see the following OSH Answers:
- general being or operating on ice that is damaged or where the ice strength is compromised
- general overloading the ice
- general being or operating on areas of thin ice
- physical being or working in the cold
- physical Cold Environments - Control Measures
- physical Cold Environments - Health Effects and First Aid
- physical Cold Environments - Overview
What are the characteristics of ice over water?
Fresh water freezes at 0°C, and sea (salt) water freezes at about -2°C.
The strength of the ice depends on many factors, including:
For example, solid, clear blue ice forms when water freezes and is generally considered to be the strongest type of ice. White opaque ice (also known as "snow ice" that is formed when there is air trapped in the ice) has a high air content and is not strong.
The strength or integrity of the ice is also affected by:
- context quality of the ice (clear, white, etc.)
- context colour of the ice
- context thickness of the ice
- context the presence of cracks
- context the ice and air temperatures during the several days before
- context snow cover
- context size and depth of water under the ice
- context if there is moving or calm water below the ice
- context dry or wet cracks
- context presence of snowbanks
- context thermal contraction or expansion cracks
- context warming of the ice
- context high winds
- context water level changes
How thick should the ice be before it is safe to walk or travel on?
Essentially, there is no absolutely "safe" ice.
Ice must have a minimum density to be considered safe to walk or travel on. The thickness and hardness required increase in proportion to the weight of the load and how it is distributed on the ice sheet.
Ice is constantly changing. In addition to the characteristics of the ice mentioned above, the ability of the ice to support a load depends on:
In addition, ice bends when a load is placed upon it. While the ice may appear rigid, ice will flex depending on its temperature, the weight of the load, etc. Cracking may occur when the ice is overloaded. Under extreme loads, the cracks can grow and merge to cause the ice to collapse.
If walking or working on foot,
Canadian Red Cross recommends that ice thickness should be a minimum of:
- context the weight and distribution of the load(s) on the ice
- context an unintended stationary load on the ice (when a load "sits" or stops on the ice)
- context the speed of the vehicle
- context other traffic or loads on the ice
- context frequency of loads
- context continuous use areas (such as ice crossings, parking areas, or bridge sites)
- context reduced ice thickness close to shorelines
- context minimum ice thickness must be at least 10 cm (4 inches) of clear, good quality ice
- context if you plan to be in one area for more than 2 hours, the ice must be at least 15 cm (6 inches)
- context check ice thickness by working and walking in pairs. Wear floatation suits and be at least 10 m apart (32 feet)
- context be trained in rescue and self-rescue techniques
- context do not work alone
- context 15 cm (6 inches) for skating, walking or skiing in small groups
- context 20 cm (almost 8 inches) for larger groups, such as skating parties
- context 25 cm (almost 10 inches) for snowmobiles or ATVs
What are emergency preparedness measures to follow when working on ice?
Have an emergency plan to be followed in the event of breakthrough. Plan how a rescue of a person who has fallen into the ice and water may be done. In addition, drivers in remote areas should be equipped with appropriate survival equipment and food rations if they are stranded for extended period of time during whiteout conditions.
General tips include:
Please see the OSH Answers on Protection from Drowning for more information.
- context Plans, including a planned route and a return time, should be left with a responsible person who will follow up.
- context Carry an axe or ice chisel, ice auger and air temperature thermometer to measure ice thickness and air temperature.
- context A cell phone, satellite phone or two-way radio is recommended for working at remote sites.
- context Carry safety equipment such as warning devices (pylons, reflectors, flares, flags) to warn others of danger, rope, and ice picks (keep in your pocket for easy access if you end up in the water), and carry a small personal safety kit that includes a first aid kit, pocket knife, compass, whistle, fire starter kit, etc.
- context Wear layers of clothing that provide protection from wind and low temperatures but that will not get in the way of your ability to swim or float if you fell through the ice.
- context Wear a personal floatation device (PFD) and mitten-like ice claws. However if you are in a vehicle and if the PFD may hamper your escape, do not wear one.
- context Wear appropriate footwear (rubber treads, crampons) to prevent slipping.
- context Buddy up. Never go out on the ice alone, and stay off the ice if there is any chance that it may be unsafe.
- context Equipment such as a snow shovel, candles, flashlight, waterproof matches/lighter, fire extinguisher, etc.