Employing regenerative braking in trains can lead to substantial CO₂ emission reductions, especially when applied to full stop service commuter trains (8 – 17%) and to very dense suburban network trains (~ 30%). Regenerative braking applied to freight trains can also lead to CO₂ emission reductions, albeit considerably lower than for full stop service trains (~5%). When regenerative braking is employed, the current in the electric motors is reversed, slowing down the train.

The modal split for freight transport varies greatly by region, and is largely determined by geographical and economic factors. However there is a common trend towards more use of road transport, at the expense of rail and water transport. The latter modes have a substantially better environmental profile, but are limited by longer delivery times and the necessity of pre- and post-haulage by truck, i.e. inter-modal transport. In the logistic chain used nowadays, there are small local stocks and fast on demand delivery is required.