Contract NEC3 ECC Option B
On one of our projects the designers have revised the drainage during the contract period. The contractor has assessed the compensation event using defined cost and in doing this they have correctly taken account of both the additions and the omissions at defined cost, (i.e. not used the BQ values for the omissions).
This is further complicated because road crossings were originally going to be carried out via open cut. However early on in the project the Contractor opted to use guided auger boring in these locations.
This brought additional cost to the Contractor but reduced programme time, reduced traffic management cost, lane closures, night work, and carriageway reinstatement.
So my question is, when assessing the defined cost of the omission, should it be based upon the theoretical costs of open cut (priced at time of tender) or auger boring (chosen method of works by the contractor).