Most people don't think about their local highway departments unless they're inconvenienced by road construction, for instance, or a bad plowing job during a snowstorm. That's how governments work after all---people don't give them much thought until something goes wrong.
In Colorado, which sports some of the country’s worst (or best, depending on your view) weather, keeping the highways open when snowfall is measured in feet is a monumental task. Some mountain passes in the state get more than 400 inches of snow per year. The law requiring that big rigs carry chains to help with traction in winter weather is in effect from September to June. Loveland Pass, at 11,990 feet and with a steep 6.7 percent grade, is kept open all winter for trucks hauling hazardous materials that can't go through the famous Eisenhower Tunnel.
All told, Colorado's Department of Transportation (CDOT) has one of the toughest jobs of any highway department in the country: keeping the roads open even with all that white stuff. They work with state and federal agencies, follow weather a thousand miles and many days away, move employees all over the state, and track a plowload of data points, right down to pavement temperature, to push back against Mother Nature.
It begins with the National Weather Service, which has a number of forecasting offices around the state. CDOT, responsible for more than 9,000 miles of road (more than 23,000 lane miles), receives daily briefings about what's brewing off the Pacific Coast that could impact the state more than 72 hours out. As storms approach, forecasters with the Colorado Avalanche Information Center provide more imminent forecasts.
When a big storm is imminent, CDOT holds briefings every 12 hours and all affected agencies are invited, including the state patrol, county-level Office of Emergency Management personnel and sheriff’s departments. "Everybody's invited to participate and get an update on the status of the storm and to see how we can help each other,” says Kyle Lester, CDOT's director of highway maintenance.
As the rough weather closes in, the supervisors of the state’s eight “maintenance sections,” each with 100-220 employees, begin calculating staffing levels, the status of equipment (like plow trucks and front end loaders), and stockpiles of "product" like salt, sand, and magnesium chloride, a liquid deicer. CDOT aims to have 80 percent readiness on both people and equipment. Product needs to be planned far in advance, to ensure ample supplies of the many tons of materials that plows will spread on the road over the course of a winter.
In the 24 hours before a weather event arrives, CDOT pulls data from traffic management company Iteris. That info gets plugged into its Maintenance Decision Support System (MDSS), basically a computer system that connects plow trucks, supervisors, and statewide CDOT managers with localized estimates on things like pavement temperature and snowfall rates.
"Once we verify that the storm's coming, we start applying product,” says Lester. That product is usually magnesium chloride, a liquid deicer that lowers the freezing point of a roadway by approximately 10 degrees Fahrenheit. CDOT believes the liquid is better for the environment than solid forms of salt, because the byproduct can't wash into streams as much. It's also an improvement over sand which can become ground up by passing traffic and float in the air, sometimes causing serious air pollution problems nicknamed the "brown cloud". Sand and salt can also get flung up by passing trucks, causing chips in paint and windshields. CDOT does still use a more traditional mixture of sand and salt on mountain passes to help with traction, or sometimes a more expensive, more effective "designer" salt called Ice Slicer.
As much as 30 percent of dry product can be lost to "bounce", literally product bouncing off the road instead of sticking to the surface where it's needed, if it is spread on a roadway without being wetted down first. Many CDOT plow trucks are equipped with saddle tanks that can spray sand with mag chloride as it is sent out of the truck, but for older equipment mag chloride is simply dumped into the back of the truck and mixed up with the sand/salt mixture. Long term, CDOT plans to equip all its trucks with the saddle tanks to minimize bounce.
CDOT's performance measure is "time to bare pavement" from the end snowfall. There are ten categories of roadway including Interstate, US highway, state highway and mountain passes, based on traffic volume. On an interstate, for example, CDOT strives to keep the road on bare pavement at all times. Out of town drivers on I-70 might not be as well equipped to handle Colorado snow, lacking, say, winter tires, chains, and four-wheel drive. A less trafficked state highway in a different region might have a four-hour back to pavement goal.
Following massive floods last year, CDOT begin working up more statewide contingency plans to move people and equipment around. Starting in 2014, workers and equipment from the Eastern Plains, where there is less snow, might get moved to the vital and mountainous I-70 highway corridor west of Denver during a storm for a week at a time.
Once the storm starts, plow drivers go on 12 hour shifts. Some are sent home early, so they can come back later to ensure adequate staffing. Mechanics do 24-hour on-call shifts, since they need to respond at a moment's notice all over their districts. "Our field mechanics have the hardest job in the department," says Lester. "They're always short staffed and a lot of equipment goes down. Stuff breaks."
That’s why communication is key. Drivers stay in touch with each other via radio, and dispatch centers issue updates through the statewide traffic information system, text alerts, its road conditions website, and mobile apps. A centralized traffic operations center works to keep the media informed as to road conditions and closures.
Local patrols use established protocols as well as on-the-ground experience and a lot of gut feelings for when roads need to be closed or when to require commercial trucks to stop and chain up their tires. On the ground knowledge is extremely important too. Some of these plow drivers have been at it for decades, and they know their local roads and what sort of weather they can expect.
Once the storm is over and the roads are drivable, CDOT will go out with front end loaders and dump trucks, clearing away all the snow that plows have pushed to the side of the road. It’s essential to being ready for the next storm.
Colorado isn’t happy to merely handle snowstorms way better than Atlanta. Going forward, it’s looking to embrace big data, pulling in more information from more sources, to make better decisions. Data from civilian vehicles could be a huge boon, including information like when wipers come on, when traction and stability controls are triggered, and where the car is having trouble.
"CDOT is struggling with so much data," Lester says. "How do we grab it? How do we process it? What are we doing with it? That's our biggest challenge right now."
Communication is always an issue. CDOT uses the same dispatch centers as the Colorado State Patrol, but tying in with local law enforcement isn't always easy. "The system is there with the state office of emergency management, but there aren't tight ties regionally," Lester says. "Agencies really don't talk, even state patrol." That's part of the puzzle, and they're getting better at it.
CDOT is working to set up emergency operation centers (EOC) in each region, as well as a main EOC in Denver, which can all communicate with each other and with other state and local EOCs. "It might not be real elaborate," Lester says, "just a room with some situational awareness tools." Basically computers that can plug into the MDSS and show the real-time location of all CDOT's equipment, current and predicted weather and much more.
And then, when all the snow is clear and the roads are dry under the mountain sun? It's back to the National Weather Service briefings to keep an eye on that next Pacific storm.
