IAN 73/06 “Design Guidance for Road Pavement Foundations"allows for” restricted designs" and “performance designs”. “Performance designs” require that a departure is approved by the overseeing authority (OA). If the OA rejects the departure is this an instruction to change the Works Information in that the only option left for the contractor is to undertake a “restricted design”.
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I think it depends on what the Works Information says. Usually, the WI will require compliance with the requirements of Design Manual for Roads & Bridges and Interim Advice Notes as at a specified date. A departure, by definition, does not comply with these documents. Section 3 of IAN 73/06 Revision 1 (issued in 2009) states that Restricted Designs may be used without reference to the OO (Overseeing Organisation), but that Performance Designs require approval of the OO under the Departure from Standards procedure. It therefore appears that the last part of the second bullet of Clause 60.1(1) applies, ie. a change to the Works Information provided by the Contractor which is made to comply with the Works Information provided by the Employer does not constitute a compensation event.
That is assuming, as stated above, that the WI issued at time of tender did include a requirement to comply with DMRB and IANs etc.
A helpful answer from David to which I would only add that it may depend also on the reason for the rejection. Without more there is likely to be a presumption of reasonable conduct and stepping away from that to act wholly unreasonably may give rise to a compensation event. There are, however, quite a few if’s, but’s and maybe’s here.