The PCC and Colas guidance is here Snow and ice on the roads – Portsmouth City Council and there is a leaflet to download with a useful map showing the priority of roads 128.151 – Colas – Snow and Ice leaflet (2019 )v2.indd (portsmouth.gov.uk) Note that
Priority 1: High Street and Broad St
Priority 2, St. George’s Road, Gunwharf Road, Museum Road, Pembroke Road