18. Does the City use sand on streets?
USE OF TREATED SAND ON CITY STREETS
Treated sand is also used in the City to provide a reasonable level of safety on our street system. Salt is added to the sand (5% by weight) to enhance its performance as follows:
The first priority of application of treated sand after any snow accumulation is on the Regional Street system (Priority I), then the Bus Route and Collector system (Priority II), followed by an application on the Residential street system (Priority III).(a) It serves to keep sand fluid and workable when stockpiled throughout the cold winter months so that the stockpiles do not freeze and become unusable, and
(b) The salt has the effect of keeping the sand fluid and workable enough that it can be handled in the conveying and spreading apparatus used in the trucks that apply the treated sand to the streets, and
(c) The presence of the small quantity of salt in the mixture allows the material, under reasonable weather conditions, to stick to the icy surface of the roadway, thus reducing the tendency for the sand to be blown off the pavement surface by the wind and passing vehicles.Priority I and II Streets
Treated sand is applied to improve traction on Priority I streets when the ambient temperature is below -7°C, a temperature at which salt is no longer effective. It is applied to Priority II streets as conditions warrant ensuring a reasonable level of safety to motorists and pedestrians.The application of treated sand on Priority I and II streets is normally done on an intermittent basis along these streets, but may be continuous. After the initial application, and depending on the time of application, wind conditions, amount of traffic and any further accumulation of snow, additional applications of treated sand may be required at controlled intersections, bridges, subways, curves and inclines on the Priority I street system. The additional applications are usually made because of the significant traffic volumes and higher speeds on the Priority I streets. The action of vehicle tires at intersections dislodges the sand particles and the subsequent air movement caused by the moving vehicles blows the sand away from the wheel paths and to the side of the roadway resulting in the necessity for additional sanding.
Priority III (Residential) Streets
Operating procedures have been developed to reduce the application of treated sand on Priority III streets consistent with maintaining reasonably safe conditions. The application of sand shall be restricted to "spotting" or short bursts at controlled intersections, pedestrian corridors and crosswalks, railway crossings and inclines. There will be other locations where sanding may be required. These areas are to be identified on a "site specific" basis by the Streets Supervisor or designate.Sanding will not be undertaken in alleys except under extreme conditions and where authorized by the Director of Public Works or designate.