Ice is not nice under vehicle wheels, so our maintenance contractors use brine for anti-icing and de-icing, to help keep highways safe in winter.
Brine is crystal salt (sodium chloride) blended with water – a powerful agent that we draw upon to stop ice from forming on roads, or to transform existing ice and compact snow into liquid. Adding salt lowers the freezing point of water – almost like magic.
Typically the mix, created at a brine making facility, is about 77 per cent water and 23 per cent salt.
Anti-icing – Prevention is our Intention
When the forecast shows a snowstorm is coming, or when the weather is near freezing, or dew or fog could turn to ice, brine is used in a proactive way.
It’s distributed as an anti-icing liquid that prevents snow and ice from forming and bonding to the road. It also softens small accumulations of snow, so that plows can clear the roads to the pavement we all like to drive on.
Anti-icing brine may also be applied as winter is beginning to tighten or loosen its grip – when temperatures are less extreme and humidity is such that dew and fog can form ice. In drier, colder parts of BC, such as the Peace District, it’s more often a shoulder season tool because chillier winter temperatures go below the effective level of brine.
De-Icing – Softening Up Fresh or Compact Snow/Ice
Brine applied to existing snow and ice, makes it easier for plows to remove wintry accumulations from highways and bring the road back to bare and black.
When used as a reactive winter road treatment, it breaks the bond of snow and ice already on the highway and dissolves downward and until it reaches the pavement. Brine effectively melts snow and ice and stops freezing when temperatures are -9 C or warming.
Sometimes, before de-icing, ice blading is done. This puts small indents into compacted snow and ice, helping de-cing agents penetrate to the road.
Once de-icers are applied, a plow may be sent in to finish the job and clear the way. De-icers are not usually expected to clear every bit of ice and snow on the road on the first application. The goal is to keep the roads wet, preventing re-freeze, while our contractors work to remove the ice and snow.
Brine Blends and When to Use Them
Brine can be blended with other chlorides, like calcium or magnesium chloride, in different concentrations for different effects. Some brine blends act faster than others and some work better at lower temperatures.
Each type of chloride has properties to melt ice to a maximum freeze point. However, the closer it gets to that freeze point, the more prone it is to refreezing – which no one wants! Calcium chloride solution has significantly lower freezing point (below -50 C) compared to sodium chloride solution (-20 C).
Our maintenance specifications require contractors to clear highways that are classified as A, B or C, to bare pavement at -9 C or warmer, within specific time frames. Highway maintenance contractors apply brine to compact and ice, and monitor conditions with the aim of staying clear of refreezing. Short timeframes are set out for the contractors, for after they apply de-icing, to remove the slush and broken compact (so it doesn’t return to a hard, slippery, frozen state.)
Summoning data from various weather forecasts, contractors make their winter road treatment decisions based on the best information they have. This includes pavement temperature, air temperature, relative humidity, and the dew point (humidity in the air creates moistures on surfaces like roads). Road temperatures and other atmospheric conditions will dictate what brine solution will be used.
Brine applications are modified through all phases of a storm, based on thorough analyses of forecasted intensity and duration, temperature and type of precipitation.
Maintenance contractors are in the know about what works where, in their service areas.
“The best type of granular level decision-making comes from those who are experienced on the ground,” says Rocky Mountain District Manager Katie Ward. “Every area has micro-climates and local knowledge is extremely helpful, as well as pavement temperature readings and weather forecasts. Most ministry vehicles and maintenance contractor vehicles are equipped to detect road temperatures.”
Why Not Rock Salt ?
Brine is a staple among contractors’ large selection of recognized products to apply to reduce or remove slippery surfaces and keep roads safe and open. Treatments include various liquid anti-icers and de-icers, sand for traction, a sand/solid salt mixture, pre-wetted sand (where de-icing brine is added to sand before or during application), and solid salts.
So why pick (liquid) brine over (solid) rock salt?
It’s about choosing the right tool for the job. Brine works right away, while rock salt which needs time to liquify before it’s effective. Depending on the anticipated forecast, a contractor may choose one tool over the other. Salt brine is more effective at lower temperatures than rock salt, and it stays on the road in dry conditions, whereas rock salt can bounce off or be blown off hard surfaces like ice or pavement. Check out Mainroad Group’s video that outlines these and other benefits of brine over rock salt.
That said, sometimes rock salt – a traditional approach – is put to work. This type of de-icer is most effective when pavement temperatures are -6° C or warming. The solid form can continue working over a longer period of time versus straight liquid. However, well-graded (vs. smooth) compact is necessary to create a surface that enables rock salt to settle in and not get blown away by traffic or wind.
Driver Tip: Wash your vehicle with soap and water after winter storms and at the end of winter, to remove residue from brine, sand and salt. Be sure to spray underneath too!
Winter offers a whole range of weather conditions that can change quickly and make travel tricky. Brine makes ice vanish or keeps it away, to help you move safely on your way.
More about winter maintenance:
- A Look at Winter Maintenance on B.C. Highways (video)
- How BC Highway Maintenance Contracts Have Changed for the Better
- Why are Some Roads Plowed More Than Others?
- Winter Traction – Why Small Rocks, Instead of Sand
- Our Avalanche Crews Know Snow Flow
Tell us what your biggest challenge for winter driving is – snow, freezing rain, slush, ice or…?