Therefore, significantly more roads are now 20mph roads (an increase from approximately 870km to 13,000km), and significantly fewer are 30mph (a decrease from approximately 13,100km to 980km).
Felly, mae llawer mwy o ffyrdd bellach yn ffyrdd 20mya (cynnydd o tua 870km i 13,000km), ac mae llawer llai o ffyrdd yn rhai 30mya (gostyngiad o tua 13,100km i 980km).