Residential Streets (Tier 4) are plowed only when conditions warrant and snowplow crews are available. Tier 4 streets are not routinely plowed and de-iced because their lower traffic volumes and speeds do not typically warrant the expense. An exception is made if a street has hills and curves that could become hazardous to motorists. Snow in cul-de-sacs will normally be plowed to the center to provide the largest turning radius possible for emergency vehicles and solid waste operations. During heavy storms, snow may not be removed until the following day after arterials and collectors are plowed.