The history of the Du Toltskloof Pass goes back to the early 1800s when routes tram Cape Town to the interior were being investigated by the authorities. However, in 1845, the choice of Bains Kloof as the major new route across the mountains resulted in Du Toltskloot going back into obscurity until the early 1930s, when it again came into the limelight. Construction of the existing pass began in 1941 using Italian prisoners at war, but was only completed in 1948. By 1965 the capacity of the pass became inadequate and planning of a new route was undertaken, which resulted in the present tunnel, opened on 18 March 1988 by President PW Botha and now known as the Huguenot Tunnel.
The construction of the Huguenot Tunnel between Paarl and Worcester on National Route N1 is the largest single project yet undertaken by the National Transport Commission. A number of smaller, but equally Interesting, contracts like the construction of a pilot tunnel, the use of ground freezing methods for excavation in saturated soft material and the building of the imposing Hugo's River Viaduct prepared the scene for the main tunnel contract. In the main contract a system of selected subcontracts was very successfully applied for specialized work, with the electro-mechanical equipping of the tunnel and its control centre being the most important. As a result of successful negotiations with the main contractor, the original agreement was extended to include the excavation of the future double carriageway tunnel.
Planning, for the present Du Toitskloof project began as long ago as 1970.Owing to the energy crisis in 1973 and subsequent fuel supply problems for South Africa, there were insufficient funds available to proceed with construction of the project at the earliest opportunity. This paper descibes the history of the planning, as well as giving details on the various facets that had to be considered during the planning and design phases. The tunnel was completed and opened to traffic on 18 March 1988 by State President P.W. Botha, who also named it the Huguenot Tunnel.
A comprehensive geotechnical investigation including a pilot tunnel was carried out for the Du Toitskloof Tunnel. These investigations highlighted zones where special precautions had to be taken and significantly reduced the risk of unforeseen conditions, thus allowing more realistic tender prices for the various phases of the project.
The initial 150 m of the second bore of the Du Toitskloof Tunnel was driven through soft decomposed granite by a method of multiple headings with vacuum drainage. By comparison, excavation of the soft-ground section of the first bore was done by ground freezing.
The construction methods employed and the specialized equipment used on the project are descriptionbed. Details of the design aspects and the construction of the soft ground section to the, second tunnel are provided. An alternative technique was used: 'multiple face' excavation supported by vacuum drainage of the ground water table.
Long high-density road tunnels are potentially hazardous. Special installations are required to render them safe and to minimize the risk of accidents. This article reviews the electrical and mechanical equipment installed in the Du Toitskloof Tunnel (now renamed the Huguenot Tunnel), the longest road tunnel in Southern Africa.
The Du Toitskloof Tunnel project was the largest tender ever let by the National Transport Commission when it was awarded in October 1984. It has also made history by being the first major civil engineering contract in South Africa to make use of the selected subcontract format. This paper descriptionbes the main principles of selected subcontracting and how it was successfully used for the tunnel project. Comments are also given from both the consulting engineer's and the contractor's points of view on the use of this contract form at Du Toitskloof.
The operation and maintenance of the Huguenot Tunnel and Tollroad has been contracted out by the Department of Transport to Concor Construction, a member of the Tunnel Joint Venture. From a development phase in which client, consultant and contractor jointly participated, an operations contract was arrived at that is unique in South Africa. A suitable organization had to be planned, created, trained and installed to ensure the continuous operation of this tunnelltollroad. A brief summary of the organization and features of the contract is given.