If the physical conditions meet the tests in Clause 60.1(12), how is the compensation event assessed?
Only the difference between the physical conditions encountered and those which it would have been reasonable to have allowed is taken into account in assessing a compensation event (see Clause 60.1(12)).
In my experience this is one of the most subjective issues regarding compensation events and what ‘would (or should) have been reasonable to have allowed’ for a physical condition. Any Risk Allowances in the Prices are, by their nature, far more generic, although each physical condition event is to be assessed discretely. A further expansion on the definition of ‘experienced contractor’ might be helpful, along with some changes to the clause to define the boundary between the Employer’s risk and the Contractor’s risk. The ‘difference’ issue is fairly obvious anyway as this represents the portion of Employer’s risk, although trying to partition resources for a quotation assessment is also fairly subjective. Although the NEC form factors in probability rather than a ‘foreseeability’ test, I am not sure such matters are any easier to assess in practice.