3 Pre-salt - undertaken by drivers in gritting vehicles to apply salt at the specified rate of spread for the complete length of the scheduled routes, normally in advance of forecast ice formation
3 Bydd gyrwyr yn mynd â'u lorïau graeanu allan i ragwasgaru swm penodedig o halen ar y ffyrdd rhestredig ar eu hyd, fel rheol cyn i'r iâ a ragwelir ddechrau ffurfio.