Helping the Windy City prepare for snow

Revolutionary non-intrusive road sensor package from Vaisala

"Chicago is known for its changeable weather, but one thing is certain: it snows in the winter," says Richard M. Daley, Mayor of the City of Chicago. In fact, Chicago receives an average of 39 inches (99 cm) of snow each winter and it's up to the Snow Command Center, under the jurisdiction of the Department of Streets and Sanitation, to keep Chicago's streets free of ice and snow during inclement winter weather. When such weather nears Chicago, the city dispatches its fleet of salt spreaders/plows to the main arterial streets which are divided into 261 routes.

The City of Chicago utilizes a state-of-the-art Command Center to help manage its fleet, with access to cameras, radar, Global Positioning Satellite (GPS) and road weather sensors. Traditionally the City has relied upon pavement weather data from a network of embedded sensors in various key locations. However, these had proved expensive to both install and maintain, so the city was keen to try alternatives. Vaisala's non-intrusive pavement sensor package proved to be the solution the City was looking for. "Not only do the Vaisala sensors provide us with the data we need in a timely fashion, but they were installed in a fraction of the time and cost of traditional sensors," says Bob Richardson, Deputy Commissioner for the City of Chicago.

Enabling friction measurement

The spectroscopic measuring principle employed by the Vaisala Remote Road Surface State Sensor DSC111 delivers a substantial improvement in the type of data previously gleaned from Road Weather Information Systems (RWIS). Because the sensor uniquely measures water, black ice and white ice (hoar frost) independently of each other, it is now possible to measure the reduction in surface friction on the highway, resulting from adverse weather. For the first time the highway maintainer can now determine how slippery the road surface is, as well as measure its temperature and state.

"Being able to measure the friction of our roads helps us to measure the success of our winter operations," says Michael J. Picardi, Commissioner for the City of Chicago, "We can provide our residents and customers with objective performance indicators."