The ten year old Huguenot Toll Tunnel is in the Western Cape area of South Africa, on the N1 main road between Cape Town and Johannesburg. It was excavated as an inverted horseshoe. At present, only its south tube is operational, and has bi-directional traffic flow. Its north bore was excavated but not lined or equipped. Each portal has two 3.2m diameter fans, which serve half the tunnel. Although the fire detection and exhaust system has always functioned well, the first complaints of bad air were received soon after the tunnel opened. This article describes the research which began when it was confirmed that the tunnel's natural airflow, combined with the increase in pollutants from vehicles, adversely affected the ventilation system's performance. Extensive weather data began to be acquired in November 1996, and data analyses were performed in May 1997 and June 1998. It was found that airflows induced in the tunnel by weather often adversely affect the ventilation flows in the south tube, and that part or all of the ventilation system should be switched off in strong weather conditions. The primary objective of the new control system, which uses an expert system and is now being installed, will be to control the ventilation fans more effectively, allowing for airflows induced by the weather.

  • Availability:
  • Corporate Authors:

    Miller Freeman

    Calderwood Street
    London,   United Kingdom  SE18 6QH
  • Authors:
    • Bullock, P J
  • Publication Date: 1999-12


  • English

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Filing Info

  • Accession Number: 00788439
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Mar 3 2000 12:00AM