In reviewing main road direction signing in London, it was discovered that the principles used in rural areas were not applicable to a large conurbation containing contiguous important places. It was necessary to devise a different signing plan based on geographical areas. This has already been described in a paper given at the 1988 PTRC meeting (see IRRD 842339). This paper describes the development of rules based on identifying the separation of important destinations as an important parameter in establishing whether their interconnection requires the through traffic network. The rules proceed to identify the principle functions of links to carry radial or orbital traffic. Special rules arose where radial and orbital links intersected, to distinguish the direction taken by traffic turning onto the orbital road. Rather different issues arise in selecting a main road network to carry the heaviest (but not necessarily longest distance)traffic movements. Moreover, driver familiarity with the network can generally be assumed. The issues relate to the use of those roads which are already designed to high standards in terms of traffic carrying capacity or can readily be rendered to be so. It is argued that an in- vehicle guidance system (which provides network familiarity to any driver) might use such a network rather than the simplified network and destination pattern appropriate to roadside signposting. A limited network offers the possibility of more intensive traffic management, which has been proposed in the consultation document "Traffic in London" (Department of Transport, 1989, see IRRD 825577). The paper extends this idea in purely technical terms to the possibility of private sector involvement in conjunction with revenues derived from stationary vehicle enforcement or even road pricing.
Abstract