The aim of the project is for UIC Leaflet 421 to take into account the changed economic conditions brought about by the increase of permissible total train weight to > 1,200 t for cross-border traffic in the European Union (EU). This shall be achieved by amending the train consist rules currently set out in UIC Leaflet 421 to include total train weights > 1,200 t. For this purpose a method needs to be developed which enables the influential parameters (track radius, incline, train length and weight, etc.) to be taken into account.