Construction was divided into two phases: the lower, 12m high tier will be seperated from the 10m high tier above by a bench on which the underpass will sit.

The first tier features a stream culvert and an underpass for wildlife, such as otters, badgers, lizards, snakes and some protected species.

The complex shape of the embankment meant that close attention to detail would be required in order to get the project right. The main carriageway orientation is east-west, then the culvert and animal tunnel go north-east to south-west. However, the valley's natural sides are north-west to south-east, all of these planes had to be accounted for during the construction and this made it difficult to tie in the primaries (primary geogrids). This was a three dimensional problem because normally we like geogrid reinforcement to go in horizontally.

The Bodmin embankment has been constructed with a primary layer (longer tail lengths and stronger Fortrac grades) for every 1m lift, with a secondary layer midway between each primary. This means site workers form the face with wraparound lifts of 500m, typically backfilled with 250mm deep layers of fill compacted to 95% of maximum dry density.