A control system, known as Gertrude, has been used since 1976 in the central area of the city to maintain and improve peak flow, give emergency vehicles priority, aid bus movements and remove congestion from critical areas. A "Bottle of Bordeaux" concept is used to model the system, where the orifice gives the limit to the throughput, the neck gives the method of control and the bottle provides a reservoir for excess demands. In this way, up to 36 fixed-time plan combinations are used to ensure that the critical junctions remain clear. The area is divided into four interacting zones with nine plans for each zone. Zone plans are based on a closed-loop system metering major routes. The author describes the operation and configuration of the central computer processing system which does not rely on vehicle-actuated control of individual signals. Data from the critical outstations are transmitted from local controllers to the central computer where overall plan changes are devised and carried out. The bus priority elements allow buses right up to the stop line at critical junctions. The major difference compared with UK policy is that Gertrude applies cartesian principles whereas UK traffic engineering usually employs a pragmatic piecemeal approach. (TRRL)

  • Availability:
  • Corporate Authors:

    Printerhall Limited

    29 Newmart Street
    London W1P 3PE,   England 
  • Authors:
    • Morrish, D W
  • Publication Date: 1980-8-9

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00329589
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Report/Paper Numbers: HS-030 711
  • Files: ITRD, TRIS
  • Created Date: May 21 1982 12:00AM