The A55 had the largest number of cluster sites at 4, with no accident cluster sites on the A5, A483 and the A550.
Ar yr A55 yr oedd y nifer mwyaf o safleoedd clwstwr damweiniau, 4 ohonynt, ac nid oedd unrhyw safleoedd clwstwr damweiniau ar yr A5, yr A483 na'r A550.