The M4 had 12 accident cluster sites, which resulted in 54 accidents with a personal injury and of these 5 were classed as KSI.
Roedd 12 safle clwstwr damweiniau ar yr M4, a arweiniodd at 54 damwain a achosodd anafiadau personal ac roedd 5 o'r rheini'n ddamweiniau lle cafodd pobl eu lladd neu eu hanafu'n ddifrifol.