While the gauge conversion plan was finalized by the spring of 1936, the project was put on hold due to the Second World War.

In 1957, the state made the decision to fully nationalize the railway and convert it to the standard gauge of 1,524 mm (5 ft).

[5] The Lahti–Loviisa railway stretches approximately 77 kilometres (48 mi) long, consists of one track for its entire length, has a top speed limit of 50–60 km/h (31–37 mph), and is unelectrified.

[6] The line cuts through the municipalities of Orimattila, Myrskylä and Lapinjärvi — as well as Pernå and Liljendal, now both part of Loviisa — on its way to the southern terminus of the Valko harbour.

[3] Since 1970, the line has exclusively served freight traffic, the bulk of which consists of coal bound for the Port of Loviisa from Russia.