The contracts cover the provision of routine, winter and emergency maintenance as well as renewal and improvement works, including design and supervision.
The south western contract has an estimated total value of £690m while the value of the one for the south east is put at £720m. The initial contract term is eight years with an option to extend for up to a further four years.
Maximum indicative value thresholds will be included in the contract for different categories of work. Transport Scotland expects to invite five bidders to the next stage for each contract.
The tranche for the northern areas will be tendered in 2020. No company can be part of the winning team for more than two units - one in the north and one in the south.