Erex is designed to measure train energy control accurately so that operators only pay for the power they consume rather than relying on estimated bills. Eress says Erex can reduce energy consumption by up 30% and data gathered should make it possible to implement other energy reduction measures.

Eress is a non-profit organisation, jointly owned by its partners Banedanmark (Denmark), Infrabel (Belgium), Jernbaneverket (Norway), Trafikverket (Sweden), Liikennevirasto (Finland) and Swiss Federal Railways (SBB).