In 2002, Edmund Nuttall won the contract to improve the interchange of the M1 motorway and the A43 trunk road at junction 15a in Northamptonshire. The primary element of the project comprised a boxjack through the current motorway embankment, in order to upgrade the existing A43, running beneath the M1, to dual-carriageway status.
The Highways Authority would allow no closure of this arterial route and imposed maximum allowable carriageway heave and settlement contour limits throughout the jacking period. In addition, they required observational verification of the results in real time.
itmsoil were involved in the project from a very early stage and proposed an innovative solution, using 2 Robotic Total Stations operating in reflectorless mode. Each instrument was installed on a column 15m above the carriageway, cycling automatically, every 30 minutes, through a 1-2m grid of virtual points co-ordinated three-dimensionally across both carriageways throughout the whole zone of influence.