Difference in Winter Road Treatments NH

Difference in Winter Road Treatments NH

Alex Dobbins

I am writing this quite late, specifically the day before publishing; however, this is also the day after a 2 hour delay. I have only noticed the roads being salted in the presence of ice this winter; however, I noticed when driving to school yesterday, my neighborhood had been sanded instead. This got me wondering… what are roads treated with depending on different factors and conditions?

Regular rock salt

This is easily the most common anti-ice solution --- rock salt is applied to roads usually during a storm, in temperatures above 15-20°F, since that is when it is most effective.

Rock salt + magnesium chloride or calcium chloride

At temperatures below 15°F, regular rock salt becomes significantly less effective, meaning that a different anti-icing treatment should be used. Usually, regular rock salt is mixed with a chemical like magnesium chloride or calcium chloride, as the rock salt can still provide good traction, whilst the assisting chemicals are much more effective at lower temperatures, usually well into the negatives.

Sand

Sand is used in lieu of salt to help assist with traction on slick roads, usually at lower temps. It also works better in cases when snow is compact/packed. It can also be used as a pre-treatment if it is too cold for anything else, or if the pavement is wet, meaning a salt brine will likely be ineffective.

Salt brine

As opposed to the other options, this one is applied before storms; the pavement must be dry. A 23% concentration of salt mixed with other chemicals is applied to dry pavement before a storm, and this makes it harder for any snow or ice to physically bond to the pavement--- reduces the need for lots of salt, and makes plowing easier.

Factors

There are many factors other than current weather conditions that go into towns & transportation departments choosing what treatment to use; cost is a major one. Regular rock salt and sand are extremely cheap (most state transportation departments have a large stock of sand) - cheap options that work quickly. Magnesium & calcium chloride are both significantly more expensive, and have other negatives like having to be used at specific times to be effective. 

Apart from cost, environmental impact is a major consideration. Anything including salt or sand can contaminate waterways and wells, and impact wildlife. There is essentially no treatment that does not negatively impact the environment in some way. 

Additionally, impact on vehicles is a big factor. The use of salt on roads causes vehicles to rust, as when the salt mixes with water, it causes steel to oxidize (rust) quicker. Over time, and after many winters, this weakens and destroys the steel beams that hold vehicles up, and can completely total a car after a while. Fortunately, modern cars usually come with good undercoatings that protect those important beams from being impacted so quickly.

Works Cited

https://www.michigan.gov/mdot/-/media/Project/Websites/MDOT/Programs/Highway-Programs/Environmental-Efforts/Stormwater-Management/Education/Articles/Winter-Road-Maintenance.pdf?rev=7d993fa5fe2f4e1fb3531f066a745f77&hash=54040AC3ED8AF69144FB8CAB3C96C29B 

https://www.mass.gov/info-details/road-treatment-types#:~:text=Sand%20*%20Sand%20is%20inexpensive%20and%20effective,roadsides%2C%20and%20storm%20drains%20and%20disposed%20of. 

https://www.newenglandrust.com/car-rust-from-salt