Appendix 1: The environmental capacity of streets

Appendix I: The environmental capacity of streets

1

It was suggested in Chapter II (paras 129-132) that every street must have two capacities for traffic—a crude capacity related only to the movement and parking of vehicles, and an environmental capacity in which account is taken of the need to restrain the volume of traffic in order to maintain environmental standards. It was further suggested that although the street, as a form of layout, is basically unsuited for motor traffic, it is nevertheless bound to form the backbone of towns for a long period ahead, and therefore the estimation of environmental capacity must be very important in planning the future function of many streets. Whilst we have had no opportunity to study the matter in depth, we think it may be useful to describe our tentative approach because it indicates the direction in which further work is required, and because the cases we examined considerably influenced our approach to our subject. We also think it may be of value to venture some opinions, however provisional, of the acceptability or otherwise of some actual traffic flows in some actual cases, because at the present time there is practically no yardstick by which conditions can be judged.

2

The Appendix is in two parts. The first deals with residential access streets, and the second with non-residential access streets.