The 25km line will link Keilaniemi, Otaniemi and Leppävaara in Espoo with Haaga, Pakila, and Oulunkylä in northern Helsinki before terminating at Itäkeskus in the east.

The 33-station line will closely follow the route of Line 550, Helsinki's busiest bus line with peak services operating at three-minute intervals. Line 550 carries up to 40,000 passengers per day, but the light rail line would accommodate up to 80,000, running largely on a segregated alignment with services operating at 5-10 minute intervals.

The total cost of infrastructure is estimated to be €275m and in addition to the Finnish government's €83m contribution the City of Espoo has pledged €67m towards construction.

Planning will now be taken forward at a municipal level and the two cities are expected to make a final decision in June on whether to proceed with construction. Rambøll and WSP have been appointed project planning consultants for the line and an initial project plan was completed at the start of this year.

The line is expected to open before the expiry of the current operating contract for the bus route in 2022.