Expansion on a 2.5km section of track in Western Sweden between Gothenburg and Trollhatten will be carried out by Norwegian firm Veidekke.
The SEK175m ($24.5m) contract has been awarded by BanaVäg i Väst, a joint Swedish Road Administration and Swedish Rail Administration project.
Veidekke project manager Johan Gynnerstedt said the company was delighted to win the contract and believes it will be a good development base for the companies activities.
The work on the Vänerbanan line includes substantial ground reinforcement with concrete piling and is expected to begin shortly and finish in 2013.
The overall SEK10bn ($1.4bn) expansion project involves building 75km of a four-lane road and double-track railway between Göteborg and Trollhättan, with trains running at 250kmph to cut the travel time by 15–20 minutes.