Transport chiefs will detail plans ahead of an official invitation to tender for the major road scheme this Spring.
Under present plans the bypass scheme will also be bundled together with the £100m Balmedie to Tipperty road scheme and let as a single contract.
The combined project is now expected to cost £745m, against the 2008 estimated cost of £347m.
Leeds-based Soil Engineering Geoservices has just started ground investigations along the route of the Aberdeen Western Peripheral Route, which is expected to carry traffic 28 miles around the city by spring 2018.