The calcium chloride brine is used as a pre-wetter before the snow starts as an attempt to get ahead of snow accumulating. Once the snow starts salt is used. Once the temperature drops below a certain degree plain salt starts losing it's ability to melt snow. The salt then gets treated with liquid calcium chloride so it can start melting snow again. The reason salt is used is because it is the most effective plus lowest cost method to melt snow. There are several alternatives to salt but they don't work as well and cost more money. In my state people demand the streets be clear of snow instantly and don't think about the long term damage done to cars and the environment. To meet that demand government officials dump tons of salt on the road. Me, I'd love it if salt was not used. Since people want snow free roads to drive on salt will continue to be used until a better low cost alternative is available. Or even better, people should learn how to drive on roads that have a little snow on them so salting isn't needed.