Engineering and mining firm Downer EDI has won two contracts worth about $100 million with BHP Billiton Iron Ore in Western Australia.

Under a contract worth about $40 million, Downer will design and build railworks for the Ore Car Repair Workshop at Mooka about 790km north of Perth.

Under the other contract worth about $60 million, Downer will upgrade two conveyors at Nelson Point, Port Hedland, followed by the deconstruction of the existing shiploaders.

Shares in Downer were 12 cents higher at $4.97 at 1544 AEDT.