I was interested in the same idea but based on leaving London. This led me down a rabbit hole which turned up the phrase 'time space convergence map', which is an interesting way to cartographically project this feature:
An interesting one for London is Train Times vs House Prices [1]. Shows how prices are affected by commute times (and the raw data is downloadable if you want to plot the times on a map).
Space v. time is one dimension, but energy costs and infrastructure requirements are other critical elements.
A passenger car and a long-haul airliner are about equivalently efficient, on a fuel-per-passenger-mile basis (assuming a high load factor for the aircraft, and a single occupant for the auto).
Rail is far more efficient, and time-competitive with air for modest to fair long trips (given high-speed rail).
Shipping is the most efficient form of transport by far, but also one of the slowest.
Automobiles require roads of some description, though they can flexibly shift routes across these. Aircraft and ships require ports, though have freedom of movement exclusive of these (with some choke-points: straights and canals, mostly, for ships).
Rail is almost the equivalent of "ships on land", though the right-of-way itself is required. The requirements for these are comparatively modest for basic service, though high-speed and high-capacity routes, and switching, increase requirements.
(see image half way down on the right) http://geographylaunchpad.weebly.com/the-friction-of-distanc...