2. “IN CASE OF AMBIGUITIES OR DISCREPANCIES…THE ENGINEER SHALL…ISSUE…RIATE INSTRUCTIONS IN WRITING”. The scope of the instructions which the engineer is entitled to issue in resolving an ambiguity or discrepancy in the contract is not altogether clearly expressed in the previous edition of this clause. This amendment gives the engineer the broad power to issue “appropriate instructions”, which are to be regarded as instructions under cl. 13 with a consequential liability to compensate the contractor in some cases.

As a result of this amendment, on resolving an ambiguity or discrepancy the engineer may give instructions not merely as to the “manner (in which) the work is to be carried out” as in the previous edition, but also, e.g., about the time in which the work is to be carried out, or the contents of any documents to be submitted by the contractor.

Nevertheless, two limitations stand from the 4th edition. The engineer may act under this clause only if there is genuinely an ambiguity or discrepancy in the contract; if the contract documents are clear they must usually be applied even if they produce a result which the parties obviously did not intend (N. 1). And the contractor still has no remedy under this clause for ambiguities the resolution of which cannot result in an “instruction”, for example an ambiguity about the method of payment for a claim.

3. EXTRA PAYMENT UNDER CLAUSE 13 FOR AMBIGUITIES AND DISCREPANCIES. The right to extra payment under cl. 13 as incorporated into this clause is less extensive than the contractor’s right to payment under cl. 6 of the previous edition.

Under cl. 13 the contractor is entitled only to compensation to the extent that the “instructions…involve the Contractor in delay or disrupt his arrangements or methods of construction”. The contractor is no longer entitled to extra merely because he has to do more work than he anticipated because of the ambiguity, e.g. where work is shown on one drawing and omitted from another or from the specification, except to the extent that the resolution of the ambiguity causes disruption or delay.

The only exception, specifically stated in this clause, is where the instruction requires a variation to the works. Therefore where the engineer gives an instruction involving work about which the contract documents are ambiguous, it will be necessary under this new wording for the engineer (or arbitrator or court ultimately) to decide as a matter of law the correct interpretation of the documents. If the legally correct interpretation is that the work included in the instruction is part of the original contract works, then the contractor has no remedy under this clause merely because he has been involved in cost “which by reason of any such ambiguity or discrepancy the Contractor did not and had reason not to anticipate” (as he had under the former cl. 6), but only under cl. 13 if there is any delay or disruption involved. If the correct interpretation of the contract is such that the instruction requires the contractor to carry out extra work not part of the original contract works, then the instruction will amount to a variation order with a right to valuation under cl. 52. Since “The several documents forming the Contract are to be taken as mutually explanatory”, work shown e.g., on one drawing but not on another will usually be part of the original contract work and not a variation.

Thus the wording does not achieve what might be thought to be one purpose of a clause of this kind—that irrespective of the correct legal resolution of an ambiguity the contractor should be entitled to extra payment if he was misled by it as to the work to be done.

The engineer has a duty to resolve an ambiguity or discrepancy of his own motion whenever one comes to his attention, irrespective of any request by the contractor for an instruction.

If the contractor does not raise with the engineer an ambiguity or discrepancy of which he but not the engineer has become aware, so that delay or disruption is caused or aggravated, it is suggested that when the matter eventually has to be resolved by an instruction it may not be “reasonable” as required by cl. 13 for the engineer to award the contractor any of the extra cost resulting from the contractor’s default.

The contractor may even have a general duty to notify ambiguities in the contract documents of which he becomes or possibly should become aware, with liability to the employer or third parties for failure to do so. For breach of that duty the contractor may have to bear the costs of remedial works necessary because the ambiguity was not dealt with in time (p. 396).

The incorporation of cl. 13 brings with it cl. 52 (4) about notice of a claim by the contractor for extra payment for an instruction under this clause, and inclusion of payment in interim and final certificates (subject to retention).