Chapter III – Practical studies

A restricted network

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Finally, we considered what would be the result if the local authority, while accepting that nothing could prevent the eventual build-up of private cars to the maximum, nevertheless decided that it could not face the cost of anything more than a modest network with conventional roundabouts for intersections. We assumed that the environmental standard for the shopping and business streets could not be seriously departed from, and that it would still be necessary to clear all or most of the traffic out. A possible layout is shown in Figure 100.

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A restricted network of this kind would not be capable of discharging the traffic volumes indicated in Figure 89, because the supply of road space would not meet the demand. On the assumption that means were found to restrict the use of vehicles to match the capacity of the layout, then about 2,000 parking spaces would be required in the centre instead of the 4,000 spaces shown in the previous schemes, and there would have to be a correspondingly greater reliance on public transport.

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Under these conditions, the general use of cars could increase by about 80% above the present day level, but this would still represent only about 60% of the full potential demand. In such a small town, with a large dependent rural population, it is doubtful whether any acceptable measures can be devised for restraining the use of cars. Congestion on the roads during the rush hours would therefore be inevitable. A limited amount of congestion can be accepted, but there comes a point when the intervals between vehicles are diminished and speeds are lowered, and the capacity of the road is actually reduced just when the maximum is most needed. The delays involved may be small to each individual concerned, but when added up over the years for the whole travelling public, and expressed in terms of private and social costs, they are likely to be far more than the cost of the works required to obviate the congestion.

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Another point which arises from the restricted scheme described in the preceding paragraph, is that an authority which takes cheapness as the criterion of its planning must also accept that the local community will not be able to make full use of motor vehicles, and that there will be a consequent risk of losing business to some nearby locality where better standards obtain. The particular form the risk might take is in the establishment of ‘out-of-town’ shopping centres catering specifically for car-shoppers. Such centres might be established in the vicinity of several ‘restricted’ town centres, and would prosper at their expense. With the increasing mobility offered by the motor car, it has to be faced that competition can build up between quite widely scattered centres. The planned development of suburban shopping centres may well have an important part to play in diverting some of the movement that now takes place into heavily congested centres. But we think the establishment of purely ‘out-of-town’ centres in the American style is a potential development that requires careful watching, both for the harm it could do to existing centres (for the maintenance of which many good reasons have been outlined in Chapter I), and for the acute risk that such centres would be the prelude to further urban sprawl.