For most of us Stonehenge is a monument to be enjoyed when driving past, though not necessarily 'hammering down' on the A303, as your comment suggests (NCE last week).
An earlier times correspondent commented that it was a sufficiently satisfactory view - an opinion with which I would concur.
Why not let the motorist have a passing glimpse- It is most rewarding.
To get a simple scheme at minimum cost to the Exchequer, how about making the Stonehenge monument the centrepiece of a large roundabout incorporating the A344 Devises road- If this method was adopted, provision could be made for a car park etc, for all those who wish to walk around for closer views.
Such a one way, two lane traffic system could also alleviate the current A344/ A303 junction congestion problem. Then if it was felt worthwhile, a footbridge might be provided to gain access to the Avenue and Cursus sections on the north side.
After all, an equally famous Heritage Site is Avebury where traffic manages to cross right through the centre without undue disturbance - although the volume of traffic is lower in spite of the A361 being a major lorry route. Traffic volume is something we sadly have to live with these days.
Howard Campbell (F), 5 Cleeve Court, Streatley, Reading, RG8 9PS