The problem of increasing car use and congestion in outer London - identified by David Bayliss in his letter (NCE 28 July) - was also raised at a seminar on the London Orbit study at the ICE on 4 March.
This could be of greater significance, and more difficult to solve, than the concerns over how to finance improvements on London's rail systems and manage central London traffic through congestion charging.
While the seminar in March primarily concentrated on how the Orbit study was being run, early results from modelling included a forecast that the length of journeys to work may increase from 13km in 1991 to 24km in 2016. Presumably, most of this increase would be due to car journeys.
The M25 is not merely a bypass to Greater London. It also acts - particularly on the western and northern lengths - as a spine road to the adjacent built up areas of outer London and the nearby counties of Surrey, Berkshire, Buckinghamshire and Hertfordshire.
Various alternatives have included widening the M25 or other motorways and even main roads throughout the whole area to cater for unrestrained demand - the 'Los Angeles' solution. However, the cost would be astronomic and the impact on property and the environment devastating.
It is therefore essential that central government, the Greater London Authority, the London boroughs, counties, unitary authorities and the Strategic Rail Authority agree and implement a co-ordinated regional transport strategy.
Without such an approach with adequate funding over the next 10 to 20 years, the southeast will suffer major all-day congestion. All of us in transport planning must ensure that decision makers, the general public and the business community are aware of the issues.
Phil Sulley (M), traffic planning and transportation consultant, The Glass House, Benover Road, Yalding, Maidstone, Kent, ME18 6AU