Grant is assessed on the difference between rail and road costs within the limits of the environmental benefit which arise as a result of lorry traffic being removed from roads.
Asesir y grant ar y gwahaniaeth rhwng costau rheilffyrdd a chostau ffyrdd o fewn terfynau'r budd amgylcheddol sy'n deillio o symud traffig lorïau oddi ar y ffyrdd.