Several roads west of Albany Highway in the Mount Barker, Rocky Gully, Frankland and Kojonup region are to be opened up to road trains carrying certain commodities.
Transport Minister Pam Beggs said today the decision would benefit local communities through lower transport costs.
The commodities that could be carted by road trains in the area included livestock, grain, fertiliser and wool.
Mrs Beggs said the decision to open the additional roads to road trains in the shires of Kojonup, Cranbrook and Plantagenet, was acceptable to local government and there were no structural limitations on bridges on the roads.
Main Roads would endorse road train permits on application by operators who had written agreement from the local council.