Anti-icing on structures using Fixed Automated Spray Technology
Pinet & Associates, LTD
The Ontario Ministry of Transportation has recently installed the first Fixed Automated Spray Technology (FAST) system on a Canadian highway structure. This anti-icing technology was installed in the fall of 2000 at the highway 416/401 interchange near Prescott, Ontario.
Under certain cold weather conditions, structures can freeze before the road surface and create hazardous driving conditions. During the first winter of operation the northbound 416/401-interchange structure was maintained within the Ministry's standards, but still experienced numerous traffic accidents related to the surface freezing. Icing conditions can be accurately predicted based on the detection of critical threshold parameters from road weather information systems (RWIS). The FAST system employs this information and is programmed to automatically spray chemical immediately in advance of icing conditions. The product selected was potassium acetate, a chemical that is a non-corrosive to concrete and steel and has less environmental impacts than road salts. The structure is a 165m super-elevated, high speed, "freeway to freeway" ramp with a design speed of 130km/hr and a 3000 AADT. Although there were fourteen accidents the year before, there were no weather-related traffic incidents during the first winter the FAST system has been operating, although the winter was much more severe.
During the research phase the MTO contacted several jurisdictions in the United States that are currently using similar anti-icing technologies on bridges. A Request for Information was sent to several manufacturers to determine preliminary designs and project costs. A Request for Proposals was developed as a method of procurement to provide flexibility in constructing the FAST system. The Ministry and the proponent successfully negotiated this demonstration project for a final cost of $300,000.
The team included the Ministry Consultant (Mark F. Pinet & Associates, Ltd), Area Maintenance Contractor (Cruickshank Construction), and System Installer and Equipment Vendor (Boschung). The team successfully completed all phases of the project in less than six months. Although consumption of the anti-icing product has been higher than anticipated during the first year, the relative cost of the chemical is minor by comparison to the benefits. The team is reviewing refinements to the default program parameters and minor operational adjustments to further improve performance.
For more information, please contact Paul Zimmerman, Maintenance Officer, Ontario Ministry of Transportation, at Paul.Zimmerman@mto.gov.on.ca.