Groundbreaking road sensors

Chicago is well-known for its changeable weather, and receives an average of 39 inches (99 cm) of snow every winter. The city’s Snow Command Center, managed by the Department of Streets and Sanitation, is responsible for keeping the streets free of ice and snow, and dispatches a fleet of salt spreaders/ploughs to 261 major routes when bad weather nears the city.

Traditionally, the city relied on pavement weather data from a network of embedded sensors at various key locations to provide the information needed for this, but these proved expensive to install and maintain. A non-intrusive pavement sensor package from Vaisala has proved a major step up in performance and reliability.

Thanks to Vaisala technology, Chicago is now better-prepared to deal with its tough winter weather. Photo courtesy of the City of Chicago.

Quick installation, low costs

Vaisala’s road weather sensors now play an important part in the resources available to Chicago’s state-of-the-art Snow Command Center, together with cameras, radar, and Global Positioning Satellite (GPS) sensors.

The sensors have been deployed at key locations, mainly on bridge decks, which have a tendency to freeze well before surrounding roads. By utilising existing light columns, it was possible to install them in under four hours, a fraction of the time needed for traditional sensors, and at a fraction of the cost as well.

How slippery are the roads?

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

Non-intrusive sensor solutions such as the one in Chicago are revolutionising the traditional concept of road weather information and opening up cost-effective solutions for cities, large and small, and bypassing the disruption and cost traditionally associated with obtaining critical information of this type.

The Vaisala Remote Road Surface State Sensor DSC111 enables highway engineers to determine how slippery road surfaces are, as well as roadside temperatures and overall conditions. By utilising existing light columns, Chicago was able to install its sensors in a fraction of the time needed for traditional sensors, and at a fraction of the cost.