Bryan Caplan  

Forgetting How to Drive in the Snow

Forgetting: The Basic Facts... Hire Locally...
Last night, less than one inch of snow caused massive traffic jams in DC.  Hypothesis, inspired by today's post on forgetting: Holding snowfall constant, the traffic jams will be most severe at the start of every snow season, then decline.  The reason: At the start of the snow season, people's snow driving skills have atrophied from disuse.  Practice revives them, but only as long as the snow - and the practice - continues.

Related thought: At first glance, snow driving is a physical skill, which would normally decay at a relatively slow rate.  But on second thought, it's mostly cognitive.  Remembering to drive slowly and leave buffer zones is a matter of concentration, not dexterity.

HT: Dan Lin

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COMMENTS (15 to date)
Greg writes:

If it's any consolation, this pattern repeats itself every year in every Canadian city every winter, though it's funniest in Vancouver. At the first snowfall, there are scores of accidents and fender benders, then everyone remembers to slow down and increase following distances.

Jj writes:

There's also a whole new batch of people who are driving in snow for the very first time.

Pierre writes:

Greg is right. I've experienced this effect in both Vancouver and in Edmonton. Also, in Vancouver, if it hasn't rained for an extended period of time, it's "common knowledge" that the roads are "more slippery" the first day we experience heavy rainfall.

Carl writes:

We got 1.6 inches of snow, not "less than an inch". The snow fell on ground that had been freezing for three days and immediately turned to ice. The roads weren't treated. Nobody can drive well on ice.

The "DC drivers are so silly an inch of snow shuts down the city" angle could not be more played out.

anomdebus writes:

Why can't it be both?
Do you expect drivers to adapt as fast the first time they drive in snow as drivers who have learned in the past how to drive in snow?

Greg writes:

I guess I have two points:

  • This phenomenon doesn't require people who rarely see snow. It happens regularly to Canadians, including those who religiously change to snow tires every year; and
  • It's not like riding a bike. People who have not ridden for years can hop right on and instantly go for it. This requires a conscious shift in driving behaviour, like remembering how to walk on ice (keep your centre of mass further forward).

JK Brown writes:

Well, the sad fact is that just a few, even one, drivers, who don't adapt to the conditions, can create havoc. Many drivers adapt to the weather conditions, but it is very difficult to adjust for the highly variable "other driver" conditions one will encounter. The latter is similar to why it is safer to drive the average speed of the traffic rather than worry about the posted speed limit.

And in DC, there is the mixing of Southern drivers with less experience and idiot Northern drivers who don't understand that snow is different down south and they don't treat/plow the roads the same.

Not to mention, the first snow hitting surface warmed roads that melt the snow leaving a film of water on the surface. In cold climes, the road is froze, which inhibits melt. Even traffic melting is quickly refrozen and broken up before it can form sheet ice.

LD Bottorff writes:

Too many people think that there is skill involved in driving on snow and ice. A bigger issue is judgement. No amount of skill allows you to weave in and out of lanes when there is snow and ice on the road. Go to Youtube and search for Russian drivers. You'll see plenty of wrecks. Russian drivers should be used to winter conditions, but there are plenty of them who don't understand that you can't control your vehicle when you drive fast on snow and ice.

Urstoff writes:

Seems to be less about the DC drivers (as other people point out, everyone has to adapt, even Canadians) and more that DC traffic is so bad in general that even minor things destroy the whole system.

bill writes:

I've read that in normal conditions, the difference between a crowded road that's moving at 50mph and stop and go traffic that averages 20mph can be as small as 5%-10% more cars. So if snow makes most drivers seek a couple extra car lengths cushion... I guess that means at rush hour it's surprising traffic moved at all.

blink writes:

I agree that forgetting plays a role here, but there are other hypotheses. First, conditions -- holding snowfall constant as you suggest -- may improve after roads are treated. By comparison, roads are particularly slick with the first rain following a dry spell, so we expect more accidents (controlling for rainfall) quite apart from forgetting effects. Second, care increases due to more frequent reminders about dangerous weather, independent of forgetting how to drive. Simply seeing snow piled up alongside the road prompts caution.

Separately, on your their of learning, we should also see a maintenance effect. Controlling for snowfall again, shorter times between last and first snowfall of the season should also lead to fewer accidents.

Tim Worstall writes:

We get exactly the same thing here in Central Europe (Bohemia). We do get snow every winter but the first couple of days are always chaos.

Jeff writes:

I grew up in Chicago, so I know snow. I've lived in Northern Virginia since 1988, and I have to agree with Carl: The snow on Wednesday created some of the slickest road conditions I've seen here in years. Something about the temperature and the lack of salt on the roads meant Wednesday's road conditions here were really, really bad. Much worse than what we'd normally get from that much snow.

David Friedman writes:

There is a game, sometimes called labyrinthspiel, in which you turn two handles to control the tilt in two directions of a wooden maze. The objective is to roll a metal ball through the maze while avoiding holes. The trick is not overshooting, allowing for the fact that when the maze goes level the ball stops accelerating but does not stop moving.

It is, I think, good training for driving in the snow. Probably also for controlling Fed monetary policy.

khodge writes:

The problem in Denver is that there are many people from many different states that have many different driving styles, such as drivers who are confident in their snow skills being impatient with drivers from warmer climes (a generic problem beyond snow-driving skills).

A secondary problem is that, with the proliferation of 4-wheel drives, too many drivers with too little experience don't seem to realize that, on ice, 4-wheel drive does not equal 4-wheel stop.

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