The M4 had 16 accident cluster sites, which resulted in 63 personal injury accidents and of these 4 were classed as KSI.
Roedd 16 safle clwstwr damweiniau ar yr M4, a arweiniodd at 63 damwain a achosodd anafiadau personal ac roedd 4 o'r rheini'n ddamweiniau lle cafodd pobl eu lladd neu eu hanafu'n ddifrifol.