Note: This article originally appeared in Traffic Technology International.
Ensuring roads are safe to use is top priority for highways agencies during the winter months. Tom Stone finds out how Michigan DOT is staying ahead of the game in the face of record snowfalls
Winter began early in Michigan. Just as in 2013, mid-November 2014 saw the northern state blanketed in the kind of deep snow residents are more used to seeing in January. In fact, on November 20, 2014, the Grand Rapids region officially announced its snowiest November on record with still 10 days of the month left to go (28.4in had fallen by 7:00pm that day; the previous record of 28.2in was set in 1895). But at least Michigan residents can take comfort from the fact that state snowplows are operating at maximum efficiency – controlled using an advanced system implemented by the DOT just in time for the early whiteouts.
The new efficiency began with the paperwork. In an innovative agreement, MDOT contracted Delcan Technologies (DTI), a Parsons Company, to provide both web-based Automatic Vehicle Location (AVL) and a Maintenance Decision Support System (MDSS). “Most states and agencies have two separate contracts,” says Tim Croze, engineer manager for the MDOT region support unit. “We’ve combined them into one. That way, we don’t have to get in between two vendors and tell them what kind of protocol to use for data and stuff like that. They work it out between themselves. DTI provides AVL GPS for our snowplow trucks. We get data from temperature sensors on our trucks and we know when the blades are down or up and the application rate of the deicing material.”
DTI is also contracted to provide the MDSS and weather forecasting components – even though the company itself does not offer this type of service. “They’ve subcontracted it to Iteris,” explains Croze. “We knew there wasn’t one vendor that provided both services, but we wanted our AVL data to feed right into the MDSS, since we are collecting weather data from snowplows.”
Critically, the kind of weather forecasting needed to direct snowplows not only on the correct routes, but also in the application of the correct type and amounts of deicing chemicals in real time, is highly detailed. A regular weather forecast can tell you what is about to fall from the sky and what the air temperature will be. However, what it can’t predict is the exact effects of this weather on pavement condition. This is due to the variable nature of many influencing factors, including pavement characteristics, environmental influences and atmospheric conditions, as well as previous maintenance activities and traffic levels.
This is where HiCAPS (Highway Condition Analysis and Prediction System), developed by Iteris, comes into play. The MDOT report AVL/GPS Use For Winter Maintenance states, “HiCAPS forecasts pavement and bridge deck temperatures using complex models to represent heat and moisture exchanges between the road, the atmosphere and pavement substrate. A key distinction setting HiCAPS apart from other models in the industry is the coupling between the mass and energy balances in the model. In simple terms, this means that when moisture (as snow, rain, frost, dew) is deposited onto the road, it also transfers energy to or from the road, and that evaporation or sublimation of moisture from the road requires the road to have an adequate amount of energy available to support those processes.”
This kind of super-accurate forecast meant that recently an MDOT supervisor was able to call in more operators several hours before the TV news predicted snow. “If you are planning to do something outside, you turn on the local news for a weather forecast,” says Croze. “But the forecast we get is weather, plus it’s forecasting what that weather is going to do to our roadways. It provides us with treatment recommendations based on science. So we know if we should treat our road with salt or some other chemical. And it gives us an application rate because we know the temperature of the roadway and how much snow is falling. So there’s a formula that tells us how much salt to apply to be just enough to melt the snow and ice.” This means precious resources are conserved, without compromising safety.
The USDOT’s assistant secretary for research and technology, Gregory Winfree, agrees efficiency in winter maintenance is paramount: “Forecasting and planning is a key consideration,” he says. “Salt and equipment repair and maintenance have very real budgetary impacts on the state.”
“Iteris updates its forecast every hour, or as necessary,” adds Croze. “Treatment recommendations are updated almost immediately. They are sent to the driver via a monitor in the cab. And they are posted online so supervisors can monitor the situation.” It’s this monitoring that initially created more problems than it solved…
Winning hearts and minds
While MDOT and its contractors concentrated on the technical side of the system, they failed to anticipate there would be problems of a more human nature. Many snowplow operators initially regarded the new system with suspicion. Some viewed it not as a helpful aid to more efficient working, but as unnecessary interference – an unwelcome eye over the shoulder.
A key lesson learned, outlined in the MDOT report, was that, “A great deal of effort is needed to promote buy-in for these technologies. To gain buy-in, it is necessary to focus more on how these tools can help with current tasks and reduce manual reporting of labor, equipment and material usage by the operator so they can focus on their maintenance activities. If buy-in, or at least tolerance, of these technologies cannot be accomplished at all levels, it will be difficult to maintain a successful program.”
One of Croze’s coworkers is Collin Castle, connected vehicle technical manager at MDOT. He is looking at ways of using the weather information in the snowplow system for a wider benefit. “We see our snowplows driving around and we know the conditions of the roadway, so we take that knowledge and couple it with other types of weather information such as radar signatures and fixed environmental sensor stations, and advisories and warnings,” says Castle. “We take that all into account and determine a location where we can provide traveler information via a roadside sign or the Mi Drive website.”
Castle is even looking to a future where it won’t be necessary to log on to a website or even look at a sign to obtain such information. He is developing roadside units that will communicate directly with vehicles.
“We could be receiving information as to characteristics of the freeway or weather,” he says. “We could then take that information and process it, and then return it back to give them some value about current situations, potentially. We’re looking at it from a two-way perspective. We can receive information off the vehicles that can give us a better understanding of how the roadway is operating from a mobility/weather/ incident perspective. But, in turn, we can provide that information back to the motorist.”
The same DSRC technology that is used for V2V and V2I is also being put to use in developing new guidance systems for snowplows. “The state of Michigan is partnering with our Intelligent Transportation Joint Programs Office in using DSRC technology to assist its plows,” reveals the USDOT’s Winfree. “Part of it is using DSRC so that the plows know what the boundaries of the roads are. I used to live in a very snowy state up north and it wasn’t uncommon for a plow to knock your mailbox over – they couldn’t see the curb. By extension, they would damage the plow blades so that’s an extra cost. DSRC technology will address all that.”
The other side of winter
Once all the snow and ice has finally melted from the roads and spring returns to the Great Lakes, MDOT is planning ways to use its forecasting technology for other purposes.
“We are looking at ways of expanding the use of this tool into other maintenance functions, not just winter maintenance,” says Croze. “We do things like herbicide spraying on our roadsides. There are very specific parameters that we need to work at. We can’t have a whole lot of wind or rain. So we think we can use this MDSS program to help us in our roadside herbicide spraying applications as well.”
As weather forecasting, and more specifically pavement forecasting, become more and more accurate, its potential applications are becoming evermore varied, as are the number of ways such information can be accessed. It seems likely that the connected vehicle of the future could add weathermen to the growing list of professions it may render redundant.