“Mae tystiolaeth lethol bod cyflymderau is yn arwain at lai o wrthdrawiadau ac anafiadau llai difrifol; a thystiolaeth gyson bod gostyngiad yn nifer yr anafusion pan gyflwynir terfynau o 20mya. Dylid nodi bod y manteision hyn yn cael eu cyflawni hyd yn oed pan nad yw’r cyflymderau cyfartalog yn gostwng i 20mya - bydd unrhyw leihad mewn cyflymder yn arwain at ganlyniad cadarnhaol. Disgwylir i ostyngiadau cyflymder gynyddu dros amser wrth i bobl ddod i arfer â’r terfynau is gan normaleiddio gyrru arafach yn sgil hynny”
“There is overwhelming evidence that lower speeds result in fewer collisions and a reduced severity of injuries; and consistent evidence that casualties are reduced when 20mph limits are introduced. It should be noted that these benefits are achieved even when average speeds do not drop to 20mph - any speed reduction leads to a positive outcome. Speed reductions are expected to increase over time as people become accustomed to the lower limits and slower driving is normalised.”