( = Appendix H recommendations Treatment Matrix for Snow Conditions Salt Type Precautionary Light or Medium Heavy Traffic Treatments Before Traffic Snow or Freezing rain Dry Salt 20g/m2 20g/m2 Pre-wet Salt Light Snow Forecast 20g/m2 20g/m2 Treated Salt 15g/m2 15g/m2 Dry Salt 20g/m2 40g/m2 Moderate/Heavy Pre-wet Salt 20g/m2 40g/m2 Snow Forecast Treated Salt 15g/m2 30g/m2 Dry Salt 1 x20g/m2 then monitor Freezing rain Pre-wet Salt 1 x20g/m2 then monitor Forecast Treated Salt 1 x15g/m2 then monitor All decisions should be taken with reference to Notes (a) to (i) below Matrix Notes The Intervention Matrix is based on low/medium traffic levels as defined in Appendix H; table H11. Available traffic survey information has highlighted that many streets within Dundee may be categorised as heavy traffic level when considering peak flow data. Salting is normally planned to be treated out with peak periods when traffic flow is lighter. Appendix H; Matrix A for dry salting, stipulates slightly greater spread rates are required for low/medium traffic level than for heavy traffic level, therefore, at this time a conservative approach has been taken and low/medium traffic levels used to specify spread rates. Based on the assessment of, uncovered storage, medium traffic flow and medium loss, Dundee will of the matrix for decision making purposes for utilise “Column C” the following reasons:- Poor Cover Salt stockpile outside and unprotected. – Traffic Medium as less than 250 vehicles per hour per carriageway – for the majority of roads out with peak times. Losses Normal as not heavy traffic after spreading and moisture – content above 2%
( = Appendix H recommendations Treatment Matrix for Snow Conditions Salt Type Precautionary Treatments Before Snow or Freezing rain Light or Medium Traffic Heavy Traffic Dry Salt Light Snow Forecast 20g/m2 20g/m2 Pre-wet Salt 20g/m2 20g/m2 Treated Salt 15g/m2 15g/m2 Dry Salt Moderate/Heavy Snow Forecast 20g/m2 40g/m2 Pre-wet Salt 20g/m2 40g/m2 Treated Salt 15g/m2 30g/m2 Dry Salt Freezing rain Forecast 1 x20g/m2 then monitor Pre-wet Salt 1 x20g/m2 then monitor Treated Salt 1 x15g/m2 then monitor All decisions should be taken with reference to Notes (a) to (i) below Matrix Notes The Intervention Matrix is based on low/medium traffic levels as defined in Appendix H; table H11. Available traffic survey information has highlighted that many streets within Dundee may be categorised as heavy traffic level when considering peak flow data. Salting is normally planned to be treated out with peak periods when traffic flow is lighter. Appendix H; Matrix A for dry salting, stipulates slightly greater spread rates are required for low/medium traffic level than for heavy traffic level, therefore, at this time a conservative approach has been taken and low/medium traffic levels used to specify spread rates. Based on the assessment of, uncovered storage, medium traffic flow and medium loss, Dundee will utilise “Column C” of the matrix for decision making purposes for the following reasons:- Poor Cover – Salt stockpile outside and unprotected. Traffic – Medium as less than 250 vehicles per hour per carriageway for the majority of roads out with peak times. Losses – Normal as not heavy traffic after spreading and moisture content above 2%
winter_maintenace_policy_2018-19_1.docx