The ministry of Infrastructure and Environment commissioned CE Delft to explore the impacts of increasing the grid voltage on Dutch railway lines to 3 kV and compare them with those resulting from other energy-efficiency measures on the rail network. Recent studies suggest that switching to 3 kV is a promising way to reduce both energy consumption and CO2 emissions. At the request of ProRail, in 2016 CE Delft compared the sustainability benefits and costs of 3 kV voltage with energy-efficiency and renewable-energy measures in non-rail sectors. This new research expands the scope of that study by comparing the costs and CO2 benefits of 10 rail measures that can be implemented with the current 1.5 kV voltage with those of raising the voltage to 3 kV. More specifically, the energy-conservation potential, CO2 reduction potential and CO2 cost effectiveness were calculated. The results are expressed in terms of annual savings potential or cost effectiveness for a 2030 horizon. In addition, the results from the 2016 study have been updated on the basis of the most recent understanding in this area.