Curious Alaska: How and where does salt get used on Anchorage roads in winter?

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Question: Why don’t we salt the roads?

Alaska’s long, cold and snowy winters can make for driving mayhem.

Maintaining Anchorage’s city and state roads involves a complex jigsaw puzzle of logistics to ensure that roadways are plowed, salted and sanded enough to be safe for drivers.

But the use of salt on roads in and around Anchorage varies. Salt is actually used on the roads here, but how frequently depends on weather conditions, which street is being maintained and, often, whether it’s managed by the state or city.

Around 15 years ago, the Municipality of Anchorage, which is in charge of maintaining more than half of roads in Anchorage, decided to stop the widespread use of salt in favor of sand, essentially small pieces of aggregate gravel, according to Paul VanLandingham, street maintenance manager for the city.

“Obviously, salt cuts through the snow and ice a little bit faster than anything else,” VanLandingham said. But that snow would get hauled off by municipal trucks and sit in snow dump sites, getting into the storm drain system and melting into the ground.

“This creates environmental issues that we’ve chosen to get away from as a municipality over the years,” VanLandingham said.

The salt ends up running into local creeks and streams that feed Cook Inlet and can hurt fish and other wildlife, said Kristi Bischofberger, watershed manager for the municipality.

So the city built places to store the sand aggregate for the winter in a warm, dry place, which eliminated the need for salt to be mixed into the sand. That was previously necessary to keep the sand from freezing into a more solid mass.

“If (the sand) were open to the outside moisture and temperatures, it would freeze and it would require salt to keep it pliable,” Bischofberger said.

That’s not to say the city avoids salt usage altogether. They use a type of liquid salt called magnesium chloride instead in targeted ways, like during freeze-thaw cycles that ice up the road and in hillier areas, according to VanLandingham.

“Because we’ve reduced our salt in the area, we can have more flexibility for using it where it’s most important,” Bischofberger said.

The city also uses the liquid come springtime once the larger sand particles have been broken down by cars. The pieces start to go airborne as the roads dry out, Bischofberger said.

Crews sweep up the particles, but they also put down salt and other liquid to essentially glue the small sand particles there while they work to pick the pieces up.

There are limitations to how effective salt can be on winter roadways. For example, a recent havoc-wreaking storm brought significant rain and snow to Interior Alaska, coating roadways in a thick layer of ice that made for treacherous driving conditions. State transportation officials said the ice was like “cement on top of the pavement.” In that situation, crews could groove the surface of the ice or place gravel to increase traction, but using salt or brine wouldn’t be effective since the road surfaces were too cold.

The Alaska Department of Transportation and Public Facilities — which is in charge of maintaining faster roadways like the Glenn Highway — uses salt on Anchorage-area roadways, except it’s in the form of brine, said Kurt Koehler, superintendent of maintenance and operations in the Anchorage district.

The crews directly apply the mixture of salt and water to roadways and also mix it with sand to help sand stick to the road better. Crews have to apply finer sand than the municipal aggregate on state-maintained roads because cars go so fast that they could flick larger pieces into windshields, Koehler said.

But fine sand poses its own environmental issues, Koehler said. Come spring, the dusty particles blow into the air after the snow melts off and also get into city storm drain systems, which takes a lot of labor to clean up, he said.

The state previously used sand mixed with salt — a third of which would immediately roll off the road — before traffic would also blow it off the road, prompting crews to revisit the same spots over and over again.

Now, using the brine has allowed them to use less sand and only slightly increase salt usage, Koehler said. The brine helps the sand stick to the road, keeping it in place longer, creating a better driving surface and saving the state money, he said.

“We’re getting a better quality product on the road and having to repeat locations less often,” Koehler said.

Plus, the salt in the brine is diluted by water — it’s slightly saltier than Cook Inlet, Koehler said — which means there’s also less salt compared to using straight rock salt on the road.

“Too much sand and too much salt are both problems, right?” said Bischofberger, with the city. “They’re both sources of pollutants, but when you try to balance them in the best way possible, then you can manage your pollutant sources in the best way for safety.”