PM pledges South Australia road upgrades

Malcolm Turnbull has returned to Adelaide with a pledge to fix well-known congestion trouble spots.

A re-elected coalition government would contribute $40 million to separate the rail line from the road at Oaklands Crossing.

This will help ease congestion at the site of 100 collisions between 2010 and 2015.

There is also a $2 million commitment to undertake planning for the upgrade of Marion Road.

The government says the investment will benefit people in the Liberal-held seats of Hindmarsh and Boothby.

In the first, sitting MP Matt Williams is hoping to hold onto his job in the face of a challenge from Labor's Steve Georganas who lost in 2013.

And Nicole Flint aims to withstand the threat of the Nick Xenophon Team, as she tries to win Boothby - formerly held by retiring MP Andrew Southcott.