Iowa DOT employs new method to fill gaps in pavement temperature data

Blowing snow 3-3 p Winter in Iowa often means snow and ice, making getting around by vehicle a little tricky. The Iowa Department of Transportation is using more data than ever to find better, more effective ways to treat roads, helping drivers get around more safely and easily.

One of the most critical data points we collect is pavement temperature. Tina Greenfield from the Iowa DOT’s Maintenance Bureau, says, “As you might expect if pavement temperatures are very cold, precipitation and moisture can freeze on the roads causing our treatment options to be different than when pavement temperatures are warmer. Having this accurate data guides our winter operations.”

The Iowa DOT has more than 70 full-service Roadway Weather Information System stations positioned around the state.

Currently, pavement temperature data is collected from more than 70 Roadway Weather Information System, or RWIS, stations positioned around the state. These permanent RWIS stations are owned and maintained by the Iowa DOT. Greenfield said, “The stations gather many different data elements including pavement temperature. These, along with sensors in our snowplow trucks, give us a pretty good idea of pavement temperatures on state and U.S. highways and interstates. With that said, a highway system as large as ours will have data gaps. When construction work disrupts an existing RWIS station  it adds more gaps in the system.”

Map of RWIS sites
From - each blue dot is an RWIS site.

To address these data gaps, the Iowa DOT is conducting a pilot project this year to purchase “data as a service.” Greenfield explained, “Our typical model has been to purchase and maintain the hardware needed to gather the data ourselves. This pilot project allows us to choose vendors who will supply and maintain the equipment, we simply purchase that data that equipment gathers.”

For the pilot project, Greenfield said the Iowa DOT focused on pavement temperature data because it is so critical to properly treating the roadways in winter weather. She said, “Our highway maintenance supervisors rely on this pavement temperature data to determine treatment options like whether to use granular salt or brine and in what quantities based on the need to either pretreat the roads or break up snow and ice. For places like the Grinnell garage, the current data stream has been disrupted because construction on the interstate in the area has removed some of the in-pavement sensors. The pilot project has a small data collection station in place so the Grinnell supervisor can still get this data.”

Greenfield says the test locations use smaller, battery-operated units that utilize infrared technology to sense pavement temperatures and relay the data over a cellular connection. She said, “This is very similar to the sensor technology we have in our plow trucks. But since we’re just purchasing the data, we don’t incur any of the cellular or power costs. Using infrared technology,  there are no sensors in the pavement to install or maintain.”

Mini RWIS Iowa 3 NW Iowa-2
The sensor mounted on top of this sign uses infrared technology to determine the pavement temperature on Iowa 3 in northwest Iowa.

While the pilot project involves only six small sensing stations located around the state, Greenfield says the expansion of the program has the potential to transform the Iowa DOT’s roadway weather data collection. “If these work out, this can be a very affordable way to get the data. This allows us to gather more data without having to invest in hardware and technology.”

Making the information easily available to our highway maintenance staff for stronger decision making is a priority. Greenfield said, “Since this first pilot project is very small with only six locations, we’ve allowed the vendor to provide the information on a separate website. If the project is successful and expanded, we’ll be requiring that the data be integrated into systems our staff already uses, making the transition seamless.”

I'm grateful to the DOT for continuing to find ways to be good stewards of our tax dollars. Purchasing the data instead of the equipment (and then maintaining that equipment, which means additional staff and expenses) is a smart way to keep costs down without compromising on operations. Kudos.

I am concerned by the use of vendors in so many areas of government. I need to be convinced this saves money. I realize this is a pilot project at this point. The DOT uses vendors for rest area staffing, Highway Helpers, and to maintain barriers in the middle of the interstates. Thank you.

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