Helsinki City Transport (HKL) has exercised an option for 20 new low-floor trams, and committed to ordering a further 29, for an extension of its light rail network to Espoo.

Transtech, the Finnish subsidiary of Škoda Transportation, said the first bi-directional pre-series unit of the 150 million contract will be delivered by the middle of 2019.

Transtech was awarded a contract in 2010 to supply 40 ForCity Smart Artic trams for HKL. Fourteen of these are now in passenger service.

The narrow-gauge trams have free-turning bogies and, to cope with the harsh winter weather in Helsinki, they are able to convert energy recovered from braking to heat the carriages. Transtech says the trams can comfortably operate at temperatures as low as -35 degrees celsius.

The new 25 km line will connect communities to the east of Helsinki to Keilaniemi in Espoo, via Oulunkylä, Huopalahti and Leppävaara.