The 23km Green Line Extension line connecting Minneapolis with St Louis Park, Hopkins, Minnetonka and Eden Prairie is now likely to cost an extra $US 145m due to higher material prices, a tight labour market and delays. It brings the Southwest Light Rail project’s total estimated construction to $US 2bn.

The county will now fund $US 190m and the railway authority, $US 14m.

Later this summer, the board is expected to vote to extend funding into 2019. It is hoped to start construction later this year.