What price safety?
Or, put another way, how many fewer vehicle crashes on Flagstaff streets during the winter are worth hundreds of dead pine trees?
And of those crashes, how serious do they have to be?
Those are the key questions the Flagstaff City Council was considering earlier this month when it asked for an update on the city practice of applying tree-killing chemical de-icer instead of cinders to some city streets after a snowstorm.
After an hour of testimony and discussion, the council decided to pull the plug entirely on de-icer this coming winter.
Our question to the council: What was the rush? It’s not as though the next blizzard is right around the corner. And as the council itself acknowledged, the data had a lot of gaps that could stand to be closed.
The biggest problem with the city’s study was a lack of specificity. It used police reports of vehicle accidents on streets treated with de-icer on what it considered “snow days,” but it didn’t break down the severity of the crashes, the location or the amount of snow that fell.
Further, there was no comparison with comparable streets that weren’t treated with de-icer during the same storms.
And although the study covered more than a decade, it failed to adjust the accident rates for the increase in traffic during a period in which Flagstaff’s population grew by more than 25 percent.
None of this is really the fault of the public works employees who gathered the data. They are not, after all, statisticians.
But the city does employ people with those skills, and the council acknowledged during its discussion that it would have liked to have seen just the kind of details mentioned above.
As it was, the key figure of crashes-per-day did show a trend toward lower numbers after de-icer began to be applied in the winter of 2007-08. The previous two winters of all cinders had crash-per-day figures that were, on average, about 30 percent higher than in the succeeding de-icer winters.
But it’s also true that the number of crashes never rose above single digits on any given day, pre- or post-de-icer. Meanwhile, tree deaths from the chemical are estimated at more than 600, and the city has said that about 200 of those are on private property and not the responsibility of the city to remove.
That seems a little callous — if a private citizen caused the death of a city tree in a park by, say, running into it in a parking lot, we’re pretty sure the city would charge the citizen for the cost of removing it.
Also, according to the city, because city crews are already equipped to do the job, the annual cost to remove a total of 200 dead pines has amounted to just $10,000, far cheaper than a homeowner would have to pay.
We’d much prefer to see the city gather more specific data on locations and conditions where de-icer is much more effective than cinders in increasing safety — not just by a factor of 30 percent but perhaps 100 percent. These might include hills and higher-speed roads like Butler and Forest.
Given the fact that ADOT will continue to apply de-icer on state roads within the city like Route 66 and South Milton, drivers will need to adjust anyway to a mix of de-iced roads and those without the chemical. Going cold turkey on de-icer without all the facts seems premature, especially when we’re at least four months away from our first snowstorm of the winter.