Do not think, on hearing this, that I am giving you a disaster scenario worthy of science fiction. I am merely stating the truth: indeed, this truth applies not only to megalopolises in faraway developing countries, but to our own cities. My proof is the severe pollution peak we recorded in Paris last year, which led to drastic measures to reduce the number of cars on the streets. This decision was unprecedented.
Thus, a city's success can turn against it. How can this be avoided?
An accessible city is one in which we can easily travel to our destination. It goes without saying that, if it is to fulfil its mission properly, a public transport network must cover those areas of the city where the most activities and dwellings are located. It has been established that the cost of transport varies depending on the density of the urban fabric in terms of housing and jobs.
It is better if a city is closely knit rather than forming a suburban sprawl, since the cost of public transport triples where there is one- tenth of the population density. It is better to curb the slow spread towards the outskirts which is now favoured by company headquarters, shopping malls, cinemas - all those centres which generate traffic and which would be much easier to reach by public transport if centrally located.
Accessibility is not just a question of networks and modes it is also a question of land-use planning policy. If we want to succeed in developing a controlled, harmonious urban environment, it is essential to co-ordinate urban planning and transport projects both at the design stage and during implementation.
Some areas in the suburbs are at risk of marginalisation and social exclusion, threatened by a mixture of violence, drugs, and unemployment. Public transport is often among the last remaining public services to survive in these areas, with all the difficulty this can entail. By continuing to run in these areas, and linking them to the rest of the city, public transport is an instrument of urban solidarity and fulfils an essential function by maintaining the social fabric.
To meet such challenges, we must be constantly ready to adapt our networks. In Paris, for example - and it is far from being alone in this - our Metro was built as a dense network to serve the heart of the city. Towards the middle of the Nineties, the RATP recorded a slight fall in its traffic. When we investigated to find out why, it became clear that one of the reasons was that structural changes had occurred in the geography and sociology of travel over the 15 previous years, resulting in disparity between our services and actual demand.
While the number of residents, and also of companies, was falling within Paris itself, the suburbs, which previously had been commuter dormitories, had seen industrial activity, shopping malls, cultural and leisure facilities spring up everywhere. Thus the suburbs were no longer satellites of the capital, but centres of urban life with their own autonomous existences.
The RATP's observation of falling traffic did not mean that fewer journeys were being taken, but that people were travelling elsewhere. For the RATP, adapting the network means above all developing links in and between suburbs.
As far as the environment is concerned, there can be no two ways about it: public transport offers a far better solution.
Alongside pollution problems, cities - particularly the big ones - are confronted with another form of nuisance: insecurity. Acts we could describe as anti-social, ranging from graffiti to seat slashing, stones thrown at buses and insults to drivers and inspectors, not to mention fraud, have multiplied.
It is true that these are less violent in appearance, but because they are repetitive and go unpunished they generate just as much unease among customers who see the networks as unsafe.
If security is not guaranteed at a high enough level, it will most certainly limit the widespread use of public transport, and thus personal mobility.
Public transport has a difficult task ahead of it. It must face economic and social challenges, environmental problems and the ever-seductive lure of the private car, supported by powerful lobbies. Nevertheless, the fact remains that public transport is the best response to urban expansion.Reuse content