Risk assessment for litter clearing on road network: FOI release

I wish to receive a copy of the Risk Assessment applied by Transport Scotland to contractors for litter clearing activities on the National Road Network. If no specific Risk Assessment is applied by TS then I would wish to receive (by electronic means) a copy of the equivalent Risk Assessments applied by the roads operating contractors employed by Transport Scotland and required / approved by Transport Scotland as the Client letting such contracts on behalf of Scottish Ministers.