An Unspoken Risk on Winter Roads in Ontario
During winter in Ontario, road safety is commonly associated with the application of sand on snow- and ice-covered roads. The prevailing assumption is that sand “improves traction” and reduces skidding.
However, field observations, supported by scientific research, reveal a more troubling reality:
Under certain conditions, sand itself can be a direct cause of skidding.
This is neither exaggeration nor anecdotal speculation. It is a phenomenon that can be explained by physics and has been documented in scientific studies related to cold-region road engineering and tribology.
A Repeated Observation on Ontario Roads
In cities such as London, Ontario, and across many residential neighborhoods in the province, drivers frequently encounter the following scenario:
- The road surface is covered with smooth ice or compacted snow
- Driving conditions feel manageable at low speeds
- Immediately after sand is applied, vehicles begin to skid
- Most noticeably during:
- Braking
- Turning
- At intersections
The paradox is striking:
The road was more stable before sand was applied.
How Sand Turns from a Solution into a Problem
To understand this, we must move beyond the simplistic assumption that “any rough material increases traction.”
What actually happens?
- Sand is spread over a smooth icy surface
- Sand does not melt ice
- The granules remain loose and unattached
- When a tire passes over them:
- The tire does not bite into the surface
- It moves over rolling particles instead
- A mobile interfacial layer forms between the tire and the road
Result:
An immediate reduction in the effective friction coefficient → skidding.
In this situation, sand does not enhance traction; it effectively behaves like countless tiny ball bearings, facilitating loss of control.
What Physics Tells Us (Not Opinion)
From the standpoint of tribology (the science of friction):
- Effective traction requires stable surface contact
- Any mobile interfacial layer reduces friction
- Loose sand on ice = a mobile interfacial layer
This is why scientific studies have concluded that:
Direct tire–ice friction can be higher than tire–sand–ice friction when sand is loose and unsettled.
In other words, sand may:
- Create momentary loss of traction
- Surprise drivers
- Increase the likelihood of low-speed crashes
Why This Is a Real Risk in Ontario
Ontario’s winter conditions combine several risk factors:
- Temperatures that reduce the effectiveness of salt
- Extensive use of sand on urban and residential roads
- Dense networks of low-speed streets and intersections
As a result:
- Skidding often occurs without speeding
- And without reckless driving
- But due to a sudden change in road surface behavior caused by sand application
When Does Sand Become a Direct Cause of Skidding?
Sand becomes hazardous when the following conditions occur together:
- Smooth ice or compacted snow
- Recently applied sand
- No melting of the surface
- Traffic movement before the sand has settled
During this short but critical window, sand is a direct cause of skidding, not a secondary or incidental factor.
Why Is This Rarely Acknowledged?
Because:
- Sand is traditionally viewed as a safety measure
- Acknowledging its short-term risks requires policy adjustment
- Lack of public awareness shifts blame entirely onto drivers
Ignoring this reality, however, does not eliminate its consequences.
What Needs to Change
The solution is not to eliminate sand use, but to:
- Explicitly acknowledge that sand can cause skidding
- Recognize a post-application risk window in winter safety policies
- Warn drivers that roads may be more slippery immediately after sanding
- Reassess application timing, quantities, and surface conditions
A Clear Conclusion
- Yes, sand can cause skidding
- Not always, but under identifiable conditions
- Ignoring this fact leads to avoidable incidents
- Acknowledging it improves public safety
Sometimes, the danger does not come from the ice itself… but from how we attempt to treat it.
Scientific References
- Cold Regions Science and Technology
Comparison between rubber–ice and sand–ice friction and the effect of loose snow contamination - Tribology International
Preliminary study of the effect of fines on sanded-ice friction - U.S. Environmental Protection Agency (EPA)
Winter Road Maintenance and Deicing Practices - Massachusetts Department of Transportation
Road Treatment Types and Traction Performance