There is a widespread assumption that transport technology has reached its apex and that further improvements are likely to be marginal.
Firstly it must be noted that such a view is not trivially implied by the known laws of physics:
* Accelerating a mass up to a given velocity takes a considerable amount of energy. So how much should it cost to move 1 ton from A to B (of the same altitude) at say 500km/hour? Conservation of momentum gives a minimum figure of around £6 assuming that this is a once off event. Needless to say the current cost of transporting such a weight is much greater.
* If it is possible to exchange momentum between vehicles slowing down and others speeding up (or using flywheels to store the energy) then the amount of energy needed to move objects from one location to another can be brought down to near 0. Practically this is not likely on earth due to the constant frictional forces (removing friction altogether currently looks unrealistic). However, simple devices called tethers could achieve such momentum transfer is space (away from a gravitational well to avoid problematic tidal forces) with almost no loss of energy due to friction and very high recovery rates of energy through regenerative braking. The technology for such tethers mainly hinges on finding a material that is sufficiently resistant to micrometeorites and solar radiation (Hoy tethers are likely candidates).
Given this the reader may want to understand what it is that is holding us back. In my humble opinion the following issues are critical:
1) Geographical happenstance: A locations altitude, latitude and longitude can determine the most feasible method of transporting things to and from it. Particularly difficult is our current position at the bottom of a big gravity well!
2) We currently lack the capability to create room temperature superconductors. With these bullet trains would become very much cheaper.
3) Materials science: The strength and weight of high tensile materials determines the weight of many forms of transport including road vehicles (including bikes), planes and even spacecraft (where the effect will be greatest). Large efficiency gains can be made by fairly modest increases in strength. Developments in materials science will lead quite quickly to better transport.
4) Atmospheric drag and other friction. This is unlikely to be eliminated for planet bound travel. However, in a space faring future this will be irrelevant (at non relativistic velocities).
We may have reached a plateau in our transport technology but the barriers we face are not absolute in nature and there are many promising developments which might make further progress in this area plausible. Most of these depend on either new materials science, better regenerative braking technology or a space faring future.
With transport, however, I'm convinced that the substituting the movement of information for the movement of matter. Then first we can do cheaply, quickly, safely and reliably. Recycling technology, energy transfer technologies and information technology will help us to do this.