To build a motorway, the route could not remain at ground level. To achieve full grade-separation, and because of the challenges of sinking the route below ground level, the entire road was to be elevated
. It was recommended that much of the land underneath could be made available for service industries or other purposes - one architect's sketch showed the LIM running on the roof of a shopping centre
- and in some places, buildings could be constructed over and under the road (imagine a building with a hole in the middle, through which the motorway passes
). The details of a suitable design to elevate a motorway without being too obtrusive was solved by designing the support piers at this early stage.