Winter is fast approaching the northern hemisphere and at the time of this writing there is freezing precipitation in the Dakotas. It’s simply that time of the year.
During a recent conversation with a meteorologist from the National Weather Service, I inquired about the long range forecast for the Midwestern United States this coming winter. He said their most reliable forecast is calling for a mild El Niño cycle with warmer temperatures and more precipitation than last winter.
Since my initial interpretation of this forecast is for distinct snow events and ice potential, let’s talk about how such events are treated by those who are in that business.
For a while I’ve been toying with the idea of diving into specifics about the science of snow removal – and it is indeed a science. Yes, I do deal with such things at work although on the managerial end of things.
Snow removal is more than just driving around and slinging material so let’s sort through this process one item at a time.
“Salt” is as generic as the word “car”. The salts used are generally magnesium chloride, calcium chloride, and sodium chloride. The choice on which to use is that of each individual entity maintaining the roadway, but as a rule of thumb magnesium chloride is more corrosive than calcium chloride which is more corrosive than sodium chloride. For those who have forgotten their chemistry, sodium chloride is table salt.
Calcium chloride can be obtained as a flake, pellet, or in liquid form. Sodium chloride is generally obtained in its raw, granular form. The color of sodium chloride will vary greatly by source location.
Personally I’m not a fan of either magnesium chloride nor calcium chloride, but that is just my opinion. In addition to eating motorists cars and snow equipment, the runoff tends to do nasty things to pavements and bridge structures. Calcium chloride, being hydroscopic, will absorb moisture, allowing residual material on pavements to sweat which can lead to refreeze.
It is also not uncommon to mix a little calcium chloride with sodium chloride. It will create what is sometimes called a “hot load”.
Sodium chloride used to be cheap but that is no longer the case. One can figure a ton of sodium chloride will cost as much, but often more, than a ton of hot asphalt. One gives two years of use, the other maybe about two hours.
It is also my understanding salt producers mine only so many tons per year for highway use. This means agencies ought be judicious in using it as replenishment during the winter can sometimes be a challenge, particularly when there will be competition for it.
Throughout the rest of this piece, if you see the word “salt” I am referring to sodium chloride.
Methods used in snow removal will vary considerably depending upon who maintains the road. Is the owner/maintainer the state, the city, the county, a township, or a road district? Don’t expect each to exercise the exact same methodology; while snow removal is a science there are those, just like with anything, who have found something that works and are reluctant to deviate even if an improvement can be made.
Think of this as the difference between fuel injection and carburetors; both work, but one is more precise.
In general one can expect larger entities to demonstrate a higher degree of finesse in snow removal. But again that is a generalized statement as boiling down the practices of many states, counties, and cities into something digestible isn’t an easy feat.
So when you are driving around in the winter and see some profound differences in how various roads have been treated, it isn’t necessarily due to “those lazy bums” at the highway department; the roads you use could be maintained by two entirely different entities with completely different methodologies. It might also be prioritization by the same owner, but we’ll talk more on that later.
As a rule of thumb, one can figure if the road has a number (I-44, US 60, Route 29) it’s owned/maintained by the state. Roads having names (Broadway, Metcalf Avenue, etc.) are not. Keep in mind some cities do name stretches of highway with a local name, such as US 61 through my old home of Hannibal being dubbed “McMasters Boulevard”; the roadsigns saying US 61 are a dead giveaway for what it really is and that locally given name is not recognized by the owner/maintainer.
Last winter I told a television reporter that winter storms are like people – there are similarities, but no two are alike. Think about all the variables: which direction is it coming from, is it building or dwindling, what time of day is it, what is the ambient temperature, is the temperature falling/rising, what is the ground temperature, what is the wind doing, what is the humidity, is it going to be preceded by rain, and what is the storm’s history? These are all important pieces of the puzzle.
Predicting what the storm is actually going to do is simply an educated guess. Like meeting a person, you don’t fully know its personality until you meet it – and it often takes some time to figure it out, just like with a new acquaintance.
If it’s snowing the roads are going to be slick; the people in the snow plows are working diligently to minimize the amount of time it’s slick and they cannot be everywhere at once. There is no winning against Mother Nature if she feels the need to be contrary.
These are often used to provide traction on some roads. Mixed with salt at various rates (anticipate x loader buckets of one with y loader buckets of another, with the salt ending up at around 20% to 30%) these abrasives are often sand, cinders, small aggregate, or manufactured sand. These materials will often depend upon local availability and could easily be something not listed here.
Cinders are useful as their black color works wonders in melting snow since any amount of daylight will warm them considerably and prompt a lot of melting. In my area cinders are the remains of burned coal, typically from electric power plants. These cinders, like most, are full of fun things like cadmium, arsenic, and chromium; despite testing showing these heavy metals aren’t leaching into water, I still don’t like cinders. Too much burning caused them to become powdery and this can present air pollution concerns when stockpiled. Cinders have a nifty habit of clogging storm sewers.
Coal fired power plants are a political hot button in the US these days so all I will say is the lack of cinder availability has provided opportunities to use other materials.
The other abrasives mentioned provide excellent traction, particularly manufactured sand due to its angularity. A lot of this material is also delightfully cheap.
There is an entire industry dedicated to snow removal. In addition to spreaders and plows for trucks made by companies such as Henderson, Viking, and Swenson, there are a number of other chemicals that can be used to amplify and/or treat sodium chloride.
One common chemical is beet juice. This is the waste product from processing sugar beets, which is one of the two prime sources of sugar in the world. Smelling like dirty feet, beet juice is a terrific substitute for calcium chloride as it is comparable in ice melting ability without being corrosive. It may give equipment and vehicles a mild brownish tinge but it washes right off with soap and water.
Beet juice can also help minimize clumping of salt. Treating a stockpile, or even a truckload, of salt with beet juice will keep it flowing. Much like the salt in a water softener can bridge and leave a void beneath the surface, similar can happen in truck-mounted spreaders. A shot of beet juice will help reduce bridging, particularly if the salt is not of a uniform gradation.
Many agencies use a combination of salt brine and beet juice. It works great in treating bridge decks to prevent icing as well as in treating roads ahead of a storm. The sugar content is enough that it will stick to the pavement so treatment of a bridge deck on, say, Thursday, will still hold frost at bay on Monday providing there has been no rain.
Just don’t dope your beet juice and salt brine cocktail with calcium chloride – if done incorrectly it can turn into a sticky, snotty mess.
One common source of angst with motorists is when they follow a spreader truck and are convinced the truck is not spreading material.
A lot of this is timing and this driver is often witnessing only a snapshot in time. In some jurisdictions hills and curves are treated first and that could be what the motorist witnessed. However, it could also be the application rate of the material.
The spreaders on many trucks are calibrated and are often tied into the hydraulic system of the truck. If an operator puts down straight salt at a rate of 200 pounds per lane mile (one lane of road one mile long is one lane mile; a two lane road one mile long will be one centerline mile and two lane miles) the application rate is quite sufficient for melting frozen precipitation but the fan of material is not readily perceptible to the human eye. It isn’t until straight salt is spread at a rate of about 800 pounds per lane mile does it become visible. At that point one is wasting material.
Another consideration is one of multiple trips. If one sees a truck and the plow is not down and no material is being spread, despite there being a skiff of snow on the road, there is the possibility of the road having been treated but the chemical not having yet done its work – or that truck is heading back to its home base for more material. Sometimes seeing a plow truck with the plow in the air makes sense as no operator wants to plow precious salt into the ditch when it’s needed on the road surface.
Like most things in life, priorities need to be identified. If a person is responsible for roads ranging from interstate highways to low volume routes, where do you start? Odds are there are more motorists on the interstate and that is where the priority should be. Lower volume roads are not unimportant but to do the most good for the greatest number of people in the shortest time possible, they should be treated secondarily.
An employee once belligerently asked why interstates are treated first, as he thought the minor roads should be the priority so people could get to work and the grocery store. My response was elaboration upon how it makes no sense to give low volume routes priority as trucks making deliveries to the grocery stores will be stuck in a parking lot otherwise known as an interstate and nobody cares to visit a grocery store with empty shelves.
It’s understandable the most important road to anyone is the one in front of their house. In an ideal world all roads would be treated equally, but the world is not a perfect place. The prioritization is also a matter of…
Trucks and Equipment
Nothing about snow equipment is cheap. One can figure a 350 horsepower tandem-axle dump truck to cost around $150,000; bump up the power and the price goes up accordingly. That’s just for the truck; a new spreader and plow can add another $40,000 or so to this.
For a historical perspective, I’ve seen purchase orders from 1999 that show comparable dump trucks for $50,000. Emission controls have been a huge driver in the cost increases of trucks over the last decade.
One piece of equipment that is seeing more use throughout the country is the Tow-Plow. Here’s a video of it in action. Trucks pulling a tow-plow generally operate best if equipped with engines in the 425 horsepower range. The tow-plow is a Missouri invention.
The tow-plow is a good aid in gang-plowing (seen in the lead picture). On multi-lane facilities it is best to plow and treat all lanes as simultaneously as possible. Otherwise, traffic will throw slush back and forth between lanes, making cleanup that much more difficult.
It also works well in keeping shoulders pushed back as with deeper snows it is easily possible to create a shelf of snow from the shoulder not being addressed as frequently as the mainline.
This video shows how to operate a Tow-Plow along with the complexity of controls inside a New York state plow truck; the truck isn’t overly unique in how it’s been equipped and how controls are arranged. It’s a very good video.
Other not uncommon equipment for plow trucks are belly plows. These work great, particularly with icepack, but the down pressure can also wreak havoc on weaker pavements.
Also used are wing plows. Wing plows are excellent for clearing snow on the shoulder of the highway.
However, the King Kong of snow removal apparatus could arguably be the snow blower. Able to blast copious amounts of snow well out of the way, these are used in various locales. The only downside is they require a certain amount of snow to function so normal fluctuations in the winter weather cycle lead to inconsistent use. And they aren’t inexpensive.
Putting a drizzle of salt brine and/or beet juice on the roadway isn’t the magic bullet; rather, it’s an optimistic endeavor that might reap benefits later on. Like some medical conditions in which the suspect organ has to be removed for diagnosis, nobody knows if treating ahead of time is successful until the storm is underway.
If all goes as planned, this treatment will slow the bonding of snow and ice to the roadway. But, as mentioned earlier, the world is not a perfect place as rain or conditions causing initial melting to refreeze will negate any positives of pretreating. There is a sentiment that treating ahead of a storm is a magic elixir; it’s not and blindly treating ahead of time can also be highly counterproductive.
If rain is in the forecast, don’t even think about treating ahead of time unless there is a forecasted window between the rain and freezing precipitation. Otherwise, it’s a waste of time and material.
Snow versus Ice
Oddly, heavy snows are, to a certain point, the least challenging as it’s a matter of let it fall, push it off. It’s entirely possible to use next to no salt in heavier events as removal will consist primarily of pushing snow.
Lighter snows, ironically, are much tougher. First, drivers seem to think a small snow shouldn’t be any big deal, which couldn’t be further from actuality. Second, the likelihood of freezing always tends to be higher as the heavier snows work as insulation.
Ice is insidious. Using copious amounts of salt, staying ahead of ice is a true challenge and this is where ground temperature can make or break a person. Sure the air temperature can be just above freezing but if the ground is frozen and it’s raining, guess what results? It’s not unusual to melt ice only to have everything refreeze in minutes. Cycle times often cannot be short enough.
Let’s just say none of it is fun, but there is an inverse relationship between precipitation depth and level of challenge – to a point. After a certain depth of snow, it gets to be a real bear as there is so much weight your equipment may not be able to push it.
Comparison of States
While storms are like people with no two being alike, similar can be said about each of the states in the US. The same no doubt holds true for each country in comparison to the others on its continent. So let’s get a feel for several states inhabited by CC’ers. This information was gleaned from winter maintenance data provided by state departments of transportation to Clear Roads for the winter of 2016-2017.
So let’s break this down by state. Keep in mind some things, primarily material usage and cost, will change from winter to winter.
Oregon: Located in the scenic Pacific Northwest, the State of Oregon maintains 19,090 lane miles of highway. The winter of ’16-’17 saw salt prices averaging $80 per ton with a total usage of 1,218 tons. The Oregon DOT has 519 plow trucks and 29 snow blowers.
On this map Oregon has been given a yellow color.
Indiana: Maintaining 26,507 lane miles of roads, the Indiana DOT (purple as seen here) has over twice as many trucks as Oregon with 1,080. Salt was noticeably cheaper in Indiana than in Oregon, averaging $71 per ton and the Indiana DOT used 185,754 tons in that winter. They have no snow blowers.
For figuring work load, Indiana has 24.5 lane miles per truck, the lowest of the outlined states.
Massachusetts: One of the geographically small states in the Northeast, Massachusetts loves its salt using 515,624 tons of salt at an average cost of $70 per ton. The Massachusetts DOT reported having 16,000 lane miles but also having the same number of centerline miles; one of these numbers is obviously wrong.
The Massachusetts DOT has 400 plow trucks and six snow blowers.
Colorado: The state of Colorado, a green and square state as seen in this map, maintains 23,000 lane miles and 892 plow trucks. With salt averaging $69 per ton, Colorado was much more judicious than Massachusetts, using 200,047 tons of salt. They have 42 snow blowers to complement their snow fleet.
Illinois: Coming in second place for most material used is Illinois with 304,500 tons used in ’16-’17. The average cost for salt was the cheapest examined at $65 per ton. With 43,186 lane miles and 1,747 trucks, the Illinois DOT has the second lowest ratio of miles per truck of any state seen here.
Illinois is seen here in yellow.
Missouri: Being a light blue and located right in the middle of the country, it’s easy to forget Missouri has the sixth largest highway system in the United States with 77,000 lane miles. That many miles will necessitate more trucks with the Missouri DOT having 1,538 trucks – roughly the number of Oregon and Indiana combined – but only two snow blowers.
With salt prices the same as in Colorado at $69 per ton, Missouri used only 70,000 tons during the winter of ’16’-17. If looking at work load a second time, Missouri has 50.0 miles per truck, over twice that of Illinois and Indiana. Oregon is the next closest at 36.8 miles per truck.
Perhaps there aren’t any, but I wanted to present this to give everyone some insight into the challenges, costs, and methodology of snow removal. As with a number of other things in life, it is much more complex than what meets the eye.
So for those of us in the Northern Hemisphere, let’s hope for a very light winter.
Pictures obtained from various sources.