rubberboots
01-22-2015, 08:43 AM
With this warmer weather a lot of us are wondering about the safety of the ice. Here's some good information on travelling on ice. I cherry picked a few excerpts below but it's very worthwhile to read both of the links yourself.
This first link contains some very good information and an easy read although a bit long. One thing I notice is not enough guys know how detrimental speed is on the ice (when travelling in a vehicle). The wave created underwater is dangerous and you shouldn't exceed 15km/hr while driving on the ice. You could be creating hazerdous conditions for you or the poor soul travelling after you.
http://www.collectionscanada.gc.ca/eppp-archive/100/201/301/tbs-sct/tb_manual-ef/Pubs_pol/hrpubs/TBM_119/CHAP5_3_e.html
"Safety Guide for Operations Over Ice"
Excerpt:
3.4 Effects of speed
3.4.1 When a vehicle travels over an ice cover, a hydrodynamic or
resonance wave is set up in the underlying water. This wave
travels at a speed that depends upon the depth of the water,
the thickness of the cover and the degree of elasticity of the
ice. If the speed of the vehicle coincides with that of the
hydrodynamic wave, the stress on the cover due to the wave
reinforces that due to the vehicle, and can increase the
maximum stress in the ice to the point of failure. The wave
action tends to crack the ice in a checkerboard pattern.
3.4.2 Particular care should be exercised when approaching or
travelling close to shore, or over shallow water, because of
more severe stressing of the cover due to reflection of the
hydrodynamic wave. Roads and vehicle approaches should meet
the shoreline at an angle of not less than 45 degrees.
3.4.3 If the weight of a loaded vehicle is one-half or less than that
determined from Figure 1 as safe for the thickness of the ice
being used, speed is not critical. When the weight is greater,
and for ice thickness less than 30 inches (75 cm), speed should
be carefully controlled and in general be kept below 10 m/h
(15 km/h).
===============================
And some more information (keeping in mind this is talking about good solid ice):
From: http://lakeice.squarespace.com/bearing-strength/
Excerpt:
Ice sheet strength increases with the square of the thickness: 2" ice will support four times more load than 1" ice, all other factors being equal.
Body Weight Breakthrough: In Vermont we have established that the 180 lb breakthrough thickness for black ice is about 1.1". This corresponds to a flexural strength of about 150 psi. Breakthrough strength in this weight range is obviously what skaters and fishermen (on foot) care about most.
Safety Factor: Ice sheets have several common features that reduce their strength. Examples include wet cracks, changes in thickness, areas that froze later than what you are presently standing on, etc. Snow drifts can inhibit ice growth and reef currents, gas holes, etc can thin the ice from underneath. Also the load you impose on an ice sheet might change very quickly if three friends skate up to you for a conversation.
http://lakeice.squarespace.com/storage/MN%20DNR.JPG?__SQUARESPACE_CACHEVERSION=1356267213 019
This first link contains some very good information and an easy read although a bit long. One thing I notice is not enough guys know how detrimental speed is on the ice (when travelling in a vehicle). The wave created underwater is dangerous and you shouldn't exceed 15km/hr while driving on the ice. You could be creating hazerdous conditions for you or the poor soul travelling after you.
http://www.collectionscanada.gc.ca/eppp-archive/100/201/301/tbs-sct/tb_manual-ef/Pubs_pol/hrpubs/TBM_119/CHAP5_3_e.html
"Safety Guide for Operations Over Ice"
Excerpt:
3.4 Effects of speed
3.4.1 When a vehicle travels over an ice cover, a hydrodynamic or
resonance wave is set up in the underlying water. This wave
travels at a speed that depends upon the depth of the water,
the thickness of the cover and the degree of elasticity of the
ice. If the speed of the vehicle coincides with that of the
hydrodynamic wave, the stress on the cover due to the wave
reinforces that due to the vehicle, and can increase the
maximum stress in the ice to the point of failure. The wave
action tends to crack the ice in a checkerboard pattern.
3.4.2 Particular care should be exercised when approaching or
travelling close to shore, or over shallow water, because of
more severe stressing of the cover due to reflection of the
hydrodynamic wave. Roads and vehicle approaches should meet
the shoreline at an angle of not less than 45 degrees.
3.4.3 If the weight of a loaded vehicle is one-half or less than that
determined from Figure 1 as safe for the thickness of the ice
being used, speed is not critical. When the weight is greater,
and for ice thickness less than 30 inches (75 cm), speed should
be carefully controlled and in general be kept below 10 m/h
(15 km/h).
===============================
And some more information (keeping in mind this is talking about good solid ice):
From: http://lakeice.squarespace.com/bearing-strength/
Excerpt:
Ice sheet strength increases with the square of the thickness: 2" ice will support four times more load than 1" ice, all other factors being equal.
Body Weight Breakthrough: In Vermont we have established that the 180 lb breakthrough thickness for black ice is about 1.1". This corresponds to a flexural strength of about 150 psi. Breakthrough strength in this weight range is obviously what skaters and fishermen (on foot) care about most.
Safety Factor: Ice sheets have several common features that reduce their strength. Examples include wet cracks, changes in thickness, areas that froze later than what you are presently standing on, etc. Snow drifts can inhibit ice growth and reef currents, gas holes, etc can thin the ice from underneath. Also the load you impose on an ice sheet might change very quickly if three friends skate up to you for a conversation.
http://lakeice.squarespace.com/storage/MN%20DNR.JPG?__SQUARESPACE_CACHEVERSION=1356267213 019