A study completed last year on the section of the route from Kiruna to the Swedish-Norwegian border concluded that track-doubling is both necessary and economically viable. The number of iron-ore trains running from mines in Sweden and eventually Finland to Narvik is forecast to rise from 20 to 44 per day by 2020, while conventional freight traffic is expected to increase from eight to 12-26 trains per day. The number of daily passenger trains could also double from six to 12 trains per day.

Trafikverket now says it will now carry out further studies to establish the extent and location of double-track sections, construction costs, and socio-economic impacts of capacity enhancement on the route.

The first phase will cover the 35km section between Peuravaara near Kiruna and Bergfors and construction could begin in 2019 if funding is secured and planning work completed.

"Our previous study showed that while simple measures are being implemented, they will not provide sufficient capacity to meet long-term traffic forecasts," says Trafikverket's northern regional director Mr Arnold Vonkavaara. "Substantial investments are needed and track-doubling meets our objectives in the most effective way."

Norwegian infrastructure manger Jernbaneverket is also looking at long-term options for track-doubling on the 43km Norwegian section of the line.