\r\nThe Czech Republic has 3217km of electrified lines, 1796km of which are equipped with the 3kV dc system and 1374km with 25kV ac.\r\nThe 3 kV network covers the northern part of the country reaching the Polish and Slovakian borders, where connecting lines are also 3kV. Slovakia has announced plans to convert its remaining 3kV lines to 25 kV, including the main corridor through the High Tatra Mountains to the steel city of Ko\u0161ice.\r\nThe southern parts of both the Czech Republic and Slovakia are 25 kV, as is neighbouring Hungary. The 3kV network is therefore considered to be an island and a barrier to long-distance passenger and freight operations. As a massive renewal of life-expired substations and other installations is due to be carried out over the next few years, the study aims to establish whether this is an opportunity to harmonise the entire Czech network on the standard European electrification system.\r\nA considerable proportion of the Czech Railways (\u010cD) locomotive fleet is dual voltage but open-access operators generally use older locomotives which are only equipped to operate on 3kV dc. It is not clear how the Czech government will deal with their interests and whether there will be compensation for these operators.