Compagnie Interafricaine De Travaux v South African Transport Services and Others

• Jurisdiction: South Africa
• Judge: Corbett CJ, Hefer JA, Vivier JA, Milne JA and Eksteen JA
• Judgment Date: 21 March 1991
• Citation: 1991 (4) SA 217 (A)
• Court: Appellate Division

Corbett CJ:

As this case demonstrates, tunnelling through mountains can be an unpredictable operation. For tunnelling is what this case is all about. On 15 February 1980 first respondent, South African Transport G Services ('SATS') called for tenders for the construction of a railway tunnel some 13,33 km in length through the Hex River mountains in the Cape Province, together with certain ancillary works. The proposed tunnel's eastern portal was to be in the vicinity of De Doorns and the western portal near Kleinstraat. The tunnel was to be at a general depth H of up to about 220 m below ground surface. The extended closing date for tenders was 16 May 1980. On that day, under cover of a letter dated 13 May 1980, a tender was submitted by a company called Spie-Batignolles SA Division, a division of Spie-Batignolles, which has its registered office in Paris ('Spie-Batignolles'). This tender was accepted by SATS on 13 August 1980. Thereafter Spie-Batignolles decided that it did not I wish to carry out the contract work. It accordingly caused the appellant, Compagnie Interafricaine de Travaux ('Comiat'), to be incorporated and it arranged for the contract to be ceded to Comiat. It is common cause that in all respects Comiat stepped into the contractual shoes of Spie-Batignolles. The tender provided for the conclusion by the J parties of a formal contract. This was entered into on 29 December 1980.

Corbett CJ

A The formal contract is voluminous and comprises the completed tender form, certain general conditions of contract ('the general conditions', also referred to as 'the E5'), certain special conditions of contract and specifications ('the special conditions'), a schedule of prices and quantities, and drawings. The contract requires the contractor to complete the works in accordance with the contract documents. The amount B to be paid to the contractor for the due performance of the contract work is a sum to be ascertained from the quantities of work carried out at the rates tendered by the contractor in the bills of quantities and/or schedule of prices. The amount of the tender, calculated in accordance with the quantities and rates reflected in the tender, amounted to R26 770 082, but the ultimate contract figure would C obviously depend upon final measurement and calculation, taking into account the actual quantities of the work performed, provisional work, price adjustment clauses, variations, etc. The date of completion is given as 12 August 1984. The contract provides for the grant of an extension of time for completion and for the payment of a penalty by the contractor for failing to complete and hand over the works by the D completion date or, where applicable, the extended completion date.

One of the documents initially made available to tenderers was a geological report prepared at the request of SATS by a consulting geologist, Mr M J Mountain ('the Mountain report'). Mr Mountain E conducted extensive investigations (starting in May 1974) into the feasibility of various routes for the tunnel. He studied geological maps and surveys, and surface conditions, tested subsurface conditions by means of 19 boreholes and conducted geotechnical tests upon rock cores. From these investigations two alternative routes for the tunnel were chosen. The report contains descriptions of the general geology of the F area, of the engineering geology of the two alternative routes and of the geomechanical classification of the rock masses likely to be encountered in the process of tunnelling along these routes. The rock in different sections of the proposed tunnels, consisting mainly of sandstone and shale, is classified geomechanically into five categories in accordance with a system devised by a Mr Z T Bieniawski. These are G (i) very good quality, (ii) good quality, (iii) fair quality, (iv) poor quality and (v) very poor quality. As regards route 1 (which was the route chosen in the contract), Mountain estimated from his investigations that 88% of it would be through rock masses falling in classes (i) to (ii), ie very good to good, 7% in classes (ii) to (iii), ie good to fair, 3% in class (iii), ie fair, and 2% in classes (iii) to H (iv), ie fair to poor. This led Mountain to conclude that in general the average rock mass of all structural regions lay within the range of Bieniawski's class (ii), viz good rock. The report nevertheless contains the caveat:

'All information contained in this report is given with a view to providing the maximum practical information for the benefit of all involved in the project. Variations from the predicted conditions may be I encountered, particularly in areas of geological contact or fault zones, due to circumstances which could not reasonably have been foreseen.'

The Mountain report is referred to in the special conditions (clause 4.6) and it is there stated that the report contains the interpretation placed upon the information gained in the investigation. Clause 4.6 J further

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A informs tenderers that the drilling cores are available for inspection and that representative core samples can be made available to tenderers for the purpose of further testing; and contains the warning:

'The interpretations given in no way absolve the contractor from making his own assessment as required under clauses 2(a) and 2(b) of the (E5).'

B I shall later refer to clauses 2(a) and 2(b) of the general conditions.

Tenderers were required to inspect the site before tendering and to this end site inspections were arranged for 5 and 27 March 1980, but tenderers were not permitted to sink additional boreholes since this would have delayed the project.

For most of its length the tunnel is designed to carry one railtrack, C but there is a section in the middle 1 447 metres in length (known as 'the loop') where the tunnel is enlarged to double width in order to accommodate two tracks.

The special conditions contain detailed provisions in regard to tunnelling. These include a stipulation (in clause 4.4) that each D tenderer is to submit with his tender a comprehensive technical report describing his proposed tunnelling methods, with particular reference to such matters as the mode of attacking the rock face, proposed tunnelling cycles, the number of complete sets of tunnelling equipment to be provided, the proposed primary support systems to be used and the proposed average daily advance rate to be achieved. In the case of the E successful tenderer, his technical report is to be incorporated in the contract and he is bound to carry out the work in accordance with the report. The special conditions further provide that the tunnelling methods used by the contractor are to be subject to the approval, from the safe-working aspect, of the resident engineer, construction ('the F engineer') and the competent authority under the Mines and Works Act 27 of 1956 and the Explosives Act 26 of 1956 (and the regulations made under those Acts); and that the contractor shall modify his methods in accordance with their requirements (clause 4.11.2). Clause 4.4 of the special conditions further provides that the contractor shall only be allowed to change his tunnelling method in the circumstances provided G for in clause 4.11.2 and with the written approval of the engineer. Both clause 4.4 and clause 4.11.2 emphasise that additional costs resulting from changes in the tunnelling methods rendering them different from those envisaged by the contractor at the time of tendering must be borne by the contractor and that no further claim, over and above the amount H to be paid for work performed as calculated in terms of the relevant rates in the contract documents, will be considered.

Such an excavated tunnel requires internal support. The special conditions make provision for two types of such support - temporary support and permanent support. Clause 4.12.1 stipulates that the contractor shall be at all times responsible for the safety and stability of the tunnel excavation and that he shall, subject to the I engineer's approval, take whatever of certain specified measures or combinations thereof he considers adequate by way of temporary support to prevent cave-ins, ground or rock falls or other failures. The measures specified in clause 4.12.1 are rock bolts, structural steel supports, wire netting or welded mesh fabric and shotcrete, a form of pneumatically applied concrete. The contractor is obliged to maintain J the temporary support until the

Corbett CJ

A permanent lining is in place. It is further stipulated that temporary support shall be provided by the contractor at his own cost, the rates tendered for tunnel excavation being deemed to include full compensation for the supply, installation and maintenance of temporary support and all direct and consequential costs involved in providing the same.

B Clause 4.12.2 states that permanent tunnel support shall consist of a concrete or shotcrete lining, as specified. The lining is to be reinforced where specified and where directed by the engineer. The contractor may be required by the engineer to incorporate temporary support systems as part of the permanent support. Where this is done such temporary support will be measured and paid for in accordance with C the contract terms and rates of payment.

In the section dealing with tunnelling in the schedule of prices and quantities figures for quantities, rates or prices per cubic metre and total amounts are given for (i) excavation in shale, (ii) excavation in quartzitic sandstone and (iii) excavation in mixed zones. In addition there is a price for 'extra-over' items (i), (ii) and (iii) for D excavation in 'fault zones'. This extra-over rate is for a provisional item relating to an additional payment over and above the rates for (i), (ii) and (iii) where fault zones are encountered. In terms of clause...