Time and Motion: how limited travel time constrains mobility

摘要

Average travel time per person has remained substantially unchanged for at least the past thirty years. The growth of travel over this period has been due largely to the higher speeds obtainable with more and better vehicles on an improved road network. This has allowed additional access to desirable destinations, which is good, at the cost of more environmental detriment (bad). Most policy and operational measures aimed at reducing congestion and improving the efficiency of the transport system have the effect of increasing speed, although generally that is not the prime intention. Given unchanged travel time, this increase in speed results in extra traffic, which undoes the sought-after improvement. The conclusion is that interventions that increase speed should be avoided, unless there is a specific requirement to increase access in a particular location. The focus of future traffic management practice should be the enhancement of the quality of the journey, while avoiding increases in the quantity of travel.