The Wisconsin Transportation Information Center (TIC), the Wisconsin Local Technology Assistance Program (LTAP) center's Winter 2009 Crossroads newsletter contains a timely review of how salt-strapped Wisconsin cities and counties are coping with expected short supplies of salt this winter. The story starts on page 4.

Bottom line: agencies are assigning a new priority to careful use of salt -- what we've been preaching as Sensible Salting for fully 40 years now. And they're considering alternative deicers. Studies like the NCHRP Report 577 have found salt the best for most storm conditions, but it's a responsible exercise for agencies to look at options. The story also reports, and laments, that some agencies are turning back the clock and expanding their planned use of salt/sand mixes.

A sidebar story beginning on page 7 asks: "Why not sand/salt mix?" and answers:

In fact, the assumption that sand-to-salt ratios of 50/50, 60/40, 70/30 or 75/25 are effective treatments is misguided. TIC agrees instead with research that shows mixing salt and sand (beyond the 2-5 percent salt needed to freeze proof sand stock piles) does not improve the effectiveness of either material.

Weigh the facts

Sand and salt work at cross-purposes. Sand improves traction when it is on top of ice or snow pack. In a salt/sand mix, as the salt begins to melt the snow pack, the sand sinks and mixes with the snow pack. Once the sand is gone from the surface, it does nothing to improve trac tion. Sand mixed with salt also reduces the melting effectiveness of the salt.

There are other costs of using a salt/sand mix to consider. It usually increases the overall application rate, so actual reduction in salt use and cost savings may be less than expected.

For example, in a change from applying salt at an application rate of 300 lbs per lane mile to a 75/25 sand/salt mix applied at 800 lbs per lane mile, the salt component of the mixture is 200 lbs per lane mile for a 33 percent reduction. Assuming a salt price of $60 per ton and a sand price of $4 per ton in this scenario, material costs go down only $1.80 per lane mile. Adjust the equation to a sand/salt ratio of 70/30 and the savings are $0.68 per lane mile. And mixing two-thirds sand with one-third salt saves nothing in material costs over straight salt.

If the route is 10 centerline miles (20 lane miles) or more, it may take an additional trip to the yard to refill the sand/salt mix. The labor and equipment costs for this trip wipe out the nominal savings on materials. Add to that the resource outlay for sand cleanup in the spring and the cost of the mixture is higher

The key point we all need to keep in mind is the life-saving, jobs-preserving mission of snowfighters. We cannot sacrifice public safety at the alter of professed fiscal concerns. If next summer's roadway rights-of-way grow a bit shaggier through less frequent mowing, that price is far more acceptable than one school bus skidding into a ditch this winter.