How mobile sensing empowered West Des Moines with critical road network data

Navigating roads during the winter weather months can be quite hazardous for drivers on our roadways. In fact, 17 percent of all vehicle crashes happen during winter conditions. to solve this problem, communities need to improve road weather data accuracy to increase safety and efficiency.

From limited budgets and increasingly severe weather events to meeting the expectations of motorists and communities that expect clear roads, the application of de-icing chemicals, spreading of salt brine, and removal of snow and ice, government agencies responsible for clearing our roads to ensure travelers’ safety face more winter weather road maintenance challenges than ever.

For West Des Moines, Iowa, that means city maintenance crews must develop a plan before winter storms move in because many operational decisions (e.g., when and how much chemical or salt to apply to which roadways, how many plows to deploy at what time and in which locations, etc.) need to be made before a storm causes problems.

Many agencies tasked with clearing roads rely on information obtained from road weather information systems (RWIS) gathering information on roads or highways. Crucially important stationary systems that deliver robust, reliable and current atmospheric and pavement conditions on roadways at all times, RWISs are expensive and, as such, tend to be thinly dispersed throughout road networks. Because RWISs are stationary, there are segments of road between the stations for which weather data is not collected but are still being significantly impacted by a winter storm.

For West Des Moines, the volume of traffic, pavement surface state and other environmental factors varied significantly enough between the current RWISs in the city to create gaps between fixed stations, impeding effective operations and mitigation. Without the ability to gather accurate data pertaining to the environmental conditions affecting their roadways in the right location at the right time, effective winter weather road maintenance becomes extremely challenging.

The Solution: Resilient Mobile Sensor Technology and Big Data

Enter mobile sensor technology and mobile data collection to supplement RWISs.

The creation of road weather forecasting models that empower transportation agency and municipality decision-makers with the information they need to keep the roads safe predominately relies on static RWISs. However, today’s mobile sensors are able to monitor a growing list of atmospheric and road conditions, including air temperature, relative humidity, dew point, road pavement temperature, road surface condition status and pavement grip to deliver data pertaining to the environment in which the vehicle is traveling.

While able to help support road maintenance decision-making through the measurement of atmosphere and pavement conditions, many mobile sensors are not rugged enough to deliver robust, accurate and reliable data from the demanding environment of a snowplow, especially during a storm.

To overcome vibrations, difficult weather conditions and other challenges posed by mounting mobile sensors on snowplows and other maintenance vehicles, the City of West Des Moines in the winter of 2018-2019 first deployed the Vaisala Mobile Detector MD30, a mobile sensor designed for any vehicle but specifically for snowplows.

Through a durable design and a patent-pending protective hood, the MD30 accurately collected and transmitted data on road surface state, grip, relative humidity, dew point, layer thicknesses of water/ice/snow, and air and surface temperature along its route and between weather stations. This information helped determine the segments of roadway that needed salt, liquid materials, plowing or a combination of treatments but after the data was transmitted, it needed to be collected and analyzed.

To better validate the data and visually identify how it looked coming back from the sensor, West Des Moines leveraged mobile data and analytical software, which provided decision-makers an in-depth view of roadways and automatically generated actionable data from weather conditions along the network.

The Result: Real-Time Data When and Where the City Needed It

Through Vaisala’s mobile sensor and advanced data collection and analysis technologies, the City of West Des Moines supplemented valuable RWIS data to better support the optimization of maintenance operations, such as snow clearance and prevention of slipperiness.

Additionally, operators found the ability to get an actual road friction reading along with data on whether the road conditions were icy or wet extremely useful.

“One of my operators was on a long route, and he could see the pavement was wet using the MD30. Then he noticed it suddenly turned icy,” Bret Hodne, public services director of the City of West Des Moines, says. “He was able to put de-icing material down in real time, instantly addressing the problem.”

Alternatively, plow operators determined de-icer applications were not necessary in many instances based on the information provided by Vaisala’s complementary mobile products.

Accessing this pavement and weather data in real time enabled West Des Moines city staff to more effectively make informed decisions before and during winter storm events. While using weather information to guide salt and liquid application rates is not a new concept, decision-makers at West Des Moines headquarters and in the cab of the plow were able to make instant decisions based on data obtained along their specific road network, taking a significant amount of “guess work” out of data interpretation. Now, road maintenance staff can make site-specific treatment decisions with confidence. As a result, the City of West Des Moines utilized only the necessary labor, equipment and resources to treat roads, ultimately seeing lower overall costs while maintaining expected levels of service goals.