The Milton Keynes grid road system is a network of predominantly national speed limit, fully landscaped routes that form the top layer of the street hierarchy for both for private and public transport in Milton Keynes, (ceremonial) Buckinghamshire. The system is unique in the United Kingdom for its innovative use of street hierarchy principles: the grid roads run in between districts rather than through them. These facilitate higher speed limits due to the absence of buildings close to the roads, although more recently the initial concept has been eroded somewhat by making some of the grid roads 40mph. High-speed motor traffic is segregated from pedestrian and leisure cycling traffic, which uses the alternative Milton Keynes redway system. All grid junctions are roundabouts, which are efficient at moving cars but disadvantageous to buses and HGVs.
The geography of Milton Keynes – the railway line, Watling Street, Grand Union Canal, M1 motorway – sets up a very strong north-south axis. If you've got to build a city between (them) it is very natural to take a pen and draw the rungs of a ladder. Ten miles by six is the size of this city – 22,000 acres. Do you lay it out like an American city, rigid orthogonal from side to side? Being more sensitive in 1966-7, the designers decided that the grid concept should apply but should be a lazy grid following the flow of land, its valleys, its ebbs and flows. That would be nicer to look at, more economical and efficient to build, and would sit more beautifully as a landscape intervention.
The grid system is made up of 11 roads aligned roughly north-south and 10 aligned roughly east-west. In early planning documents, these were simply designated as "V roads" and "H roads" respectively (for "vertical" and "horizontal"); these designations have remained popular alongside the subsequent formal (conventional) names. V-roads are named as "Streets", and H-roads as "Ways". The roads are not precisely straight and aligned, and there are several places where two H roads, or two V roads, meet at a junction. The districts enclosed by the grid roads are known as grid squares.