Initially, there were a total of 22 bridges built under or over the motorway, such as a principal bridge at Samlesbury which carried traffic over the River Ribble and the A59 trunk road, the only junction upon opening; the other principal bridge was at Higher Walton, carrying traffic over the River Darwen and the A675 road. The overall width of the motorway was , for each carriageway, for the verges and a central reservation.
