How a mere inch of snow turned DC into a total nightmare

On Wednesday evening, Washington, DC received a mere inch of snow during rush hour — and it turned into a total clusterfuck.

The roads were already cold, so that thin layer of snow turned into slippery ice. Road crews were slow to clear and salt the streets because they were overly focused on preparing for the big blizzard expected to hit this Friday. And everyone was trying to get home for the evening.

The result? Horrific traffic jams for miles:

Virtually every highway and byway in the region was backed up, some barely moving for hours. Icy exit ramps were blocked off. Some drivers simply gave up, abandoned their cars, and got out to walk:

There were dozens and dozens of accidents around DC, Maryland, and Virginia:

This has triggered endless griping/mockery/anguish about how DC can’t even handle an inch of snow. That’s not entirely true. An inch of snow is often no big deal for the city. It’s just that this particular inch was a nightmare for a few idiosyncratic reasons:

1) An inch of snow when it’s cold can be more dangerous than, say, four or five inches. A thin layer freezes more easily than a thick layer, there’s less traction, and it can be harder to see in the dark. That leads to driver overconfidence, more accidents, traffic jams, general doom, etc.

2) As Jason Samenow of Capital Weather Gang details here, there was a communications breakdown around forecasting last night’s snow. The media has been hyping the big blizzard set to hit the East Coast Friday, and, as a result, no one was focused on the snow set to hit DC Wednesday evening. A few forecasters understood that icy roads were a real risk, but they struggled to make themselves heard.

”The National Weather Service made a solid call by issuing an advisory and led some social media outreach,” Samenow writes, “but it did not release a special weather statement or coordinate with media in an effort to advertise the threat. In other words, this was a weather-enterprise-wide communication failure.”

3) Because of the communications snafu, Samenow notes, DC road crews found themselves slow to deploy salt and other chemicals to de-ice the roads. The region has the resources to clear the streets — but everyone was stockpiling for the historic snowpocalypse coming on Friday.

(There were other misfires elsewhere: Virginia officials decided not to pretreat roads on Wednesday because forecasts suggested temperatures might be so low that the treatment would only make things worse. Maryland officials didn’t pretreat the roads because their forecasts underestimated the risk of icy conditions. By the time everyone realized the roads needed serious attention, traffic jams were ubiquitous.)

4) There’s a final important factor that gets underappreciated, but is pointed out by economist Bryan Caplan here. The first snow of the season is typically the most dangerous — likely because drivers have forgotten how to navigate snowy and icy roads.

There’s academic research to back this up. In a 2004 paper in the American Journal of Public Health, Daniel Eisenberg and Kenneth Warner examined federal accident statistics across the United States between 1975 and 2000.

“The first snowy day of the year,” they concluded, “was substantially more dangerous than other snow days in terms of fatalities.” This was true even in Midwestern states that pride themselves on handling snowfall.

More specifically, the researchers found that fatal accidents were 14 percent more common on the first snowy day of the year, compared with other snowy days. It seems to take a blizzard or two for people to remember to slow down and drive more carefully.

So that inch of snow in DC wasn’t just an inch of snow. It was a perfect confluence of horrible conditions. Everyone was focused on a different storm, the roads were icy, and drivers were unprepared for winter weather. A nightmare all around.

Update: Over at Greater Greater Washington, Dan Malouff makes a good point about yesterday’s traffic mess. Suburban roads are far more prone to catastrophic weather breakdowns than urban street grids — because there are fewer alternatives when things go badly awry.

Further reading: Here’s our rundown of the massive blizzard set to hit the East Coast starting Friday.