Estimates of Autoguide traffic effects in London

The objectives of this study was to research the possible impact and operation of the vehicle guidance system Autoguide, using the Greater London Transportation Survey (GLTS) data and the London Traffic Survey (LTS) highway assignment model. The main themes of the work programme requested were: a) An analysis of the numbers and locations of Autoguide beacon sites; b) A comparison of strategic sub-networks for the routeing of Autoguide traffic; and c) The derivation of a variety of associated network statistics for different levels of Autoguide usage. Following exploratory work, it was decided to assess Autoguide in two ways: (a) allowing Autoguide traffic freedom to choose routes across the entire network, and (b) restricting Autoguide traffic to the Primary (Motorway and A Class) network. Fundamental to the method employed was the distinction drawn between Autoguide and non-Autoguide routeing behaviour. Non-Autoguide traffic was assumed not to change its route choices as travel demand varied day-by-day. Autoguide traffic was assumed to choose optimum routes both with respect to the pattern of demand on each actual day, and the other traffic. The number of assignment iterations to achieve convergence was varied, under the varying proportions of Autoguide users within total traffic, to achieve a desired minimum level of assignment convergence. The number and location of 555 Autoguide beacons was investigated in relation to their spatial dispersion and the total number of beacon encounters by traffic. Results showed that Autoguide use decreased both the total mileage travelled and travel time. See also IRRD 820242 and 820244.