Not uncommon, London, Ontario has seen a couple of intense weather systems in November, 2025 called “snow squalls” which provide an example of a localized road safety problem that may not be recognized by persons living outside the area.
It is frequently encountered that various “experts” give their advice about how to avoid collisions. When it comes to snowfall and winter road conditions advisements such as “If you see snow, go slow” are popular and they seem to make common sense. And when drivers are involved in collisions many persons express their opinions that those drivers are obviously stupid, or similar expressions. And when large numbers of collisions occur in wintery weather it seems logical that drivers become “stupider” under those conditions, and then smarter again when winter weather conditions are gone. That unscientific logic is popular, but not logical.
While there are many collisions, and many complex causes of those collisions, many do not want to accept that winter weather creates scenarios that are sometimes difficult to predict. Even in a short amount of driving experience a person can recognize that a smooth and dry road surface can provide a good level of safety because a driver can slow down or stop quickly without losing control of their vehicle. And it is also appreciated that snowy or icy road surfaces provide the direct opposite. And it seems like a simple matter of just identifying if you are riding on a smooth and dry surface or snowy, icy surface. And if drivers are unable to recognize the difference then they are “stupid”.
Through our many years of collision reconstruction we are aware that these simple conclusions are far from accurate. In-between those extremes of dry and icy surfaces there is a continuum where road surface condition changes become difficult to detect. As an example, the photo below was taken this morning, November 17th, on a roadway in London where traffic had beaten down the snowfall and created a hard-packed surface. Looking at that surface we might observe that it is shiny. But is the surface like a sheet of ice, or is it just wet, hardpacked snow?
An icy road surface could have a coefficient of friction of about .05, whereas the hardpacked wet surface could have a value of about .4. If you were travelling on an icy surface at 35 km/h it would take you about 100 metres (about 20 car lengths) to come to a stop. Yet on the hardpacked wet surface you might stop in about 13 metres (just over 2 car lengths). What if you were travelling at 35 km/h, approaching a busy intersection, and you applied heavy braking, but you slid into the intersection and were struck in your driver’s side by the front of a large transport truck? Looking down from Cloud #9 you would be able to hear all those experts claiming that you were stupid for travelling so fast on this obviously icy surface. And maybe some of those experts might experience the same predicament but it would be too late to change their mind because they would be sitting beside you on Cloud #9.
There are many instances where long-distance drivers passing through an area experience a change in weather conditions such as a snow squall. While driving for many hours they might experience dry road conditions turning into a wet surface and then progressing into a semi-snow, slush, and then progressing toward the wetness turning into ice. Looking down at the road surface a driver cannot readily appreciate whether the shiny surface is indicative of wetness or icy-ness. And the difference in tire force can be huge.
Similar results occur when snowfall exists on roadsides and a strong wind blows snow onto the road in a narrow band creating a snowdrift. A driver approaching such an accumulation of snow is often unaware of what kind of conditions exist. While snow may be visible on the road from a long distance it cannot be known if the snow is just an inch deep or several inches deep. And again this matters. An inch of snow may be inconsequential. Six inches of snow may cause a loss-of-control and a precarious consequence.
The point of this elongated discussion is that cute rhymes about seeing snow and going slow are of little help in informing drivers of what they should know. Drivers should be informed that they will have difficulty in judging the characteristics of road surfaces and misjudgment could mean death. So explanations and examples can help.
Sudden snow squalls can create a winter wonderland that is pretty to see but causes unique road safety problems.
Transient safety problems that can be created during snow squalls when intense snowfall adheres to everything, including important signage. In the example shown below, from the morning of November 17th, snow has attached itself to a cycling lane sign, a stop sign, and a pedestrian crossing sign. Not a matter to be considered lightly. However if a collision occurred would an investigator capture this happening, or could the snow fall off the signage before it is detected?
In other instances snow plowing is often a point of contention with drivers. When roads are not plowed drivers want to know why. However the nature of snow squalls is that they change direction often just by a few kilometres. And if one drove a few kilometres to the east or west of London on November 17th one would suddenly come across bare pavement. So it is sometimes difficult for the Transportation Department in the City of London to know how much snow has fallen and where.
When roads are not plowed additional problems occur that may not be obvious. While a large percentage of vehicles have the same track width they travel within the wheel tracks of similar vehicles. But when a larger vehicle is present, such as a truck or bus, the wider track width means that the wheels no longer fit in the typical wheel tracks of beaten snow. This means that the wheels of these larger vehicles end up plowing through the deep snow that has not been pressed down by previous traffic. This causes the snow to be thrown up and to the sides, and in to the lanes of opposing traffic. Drivers in those opposing lanes can suddenly become blinded by a wave of snow thrown into their windshield.
And as a final example, sudden snow squalls not only disrupt the plans of motor vehicle drivers but also those who heroically attempt to use active transportation to combat climate change. Under normal circumstances the efficiency of cycling can be greatly admired as much cargo can be carried in a cargo bike or hauled with a mini-trailer attached to its rear. Sudden snow squalls create conditions that make this efficiency difficult to attain.
In the following photos an example of a cyclist is shown hauling a mini-trailer on Hale Street in east London. The rider has been travelling southbound on a fairly level surface but then approaches the upgrade toward the elevated roundabout at Trafalgar. He stops, dismounts and then begins to walk his bike into the roadside snow.
We then observe that the cargo the cyclist was hauling in the mini-trailer stands up, and its a boy. The progress up the slope becomes easier when the cargo itself can carry itself. But many times the cargo is just stagnant cargo and more difficult to deal with.
The dilemma here is that the cyclist could be tempted to push his bike back onto the bare road surface where travelling up the slope would be easier. But he and his passenger are also not wearing helmets. They are not wearing any bright or reflective clothing and neither the bike nor the trailer is equipped with a light.
This is how cyclists can become involved in a collision. And regrettably, without thinking about their additional safety measures they become partially at fault for their consequence.
Examples like the ones shown in this article are common events that weather creates whenever a sudden snow storm brews. They are special in the vicinity of London and southwestern Ontario when a narrow band of snow, a snow squall, develops and concentrates a large amount of snow in a narrow area of only a few kilometres in width. Shifting winds mean that the squalls also shift location such that it is difficult to predict a squall’s location or where it will move, making road safety a particularly difficult matter.
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