Under clause 64.1 the Contractor assesses the quotation them-self when either the Subcontractor is late in submitting or you don't agree with the quotation. It may or may not be difficult to assess, but that is what the contract requires. Don't forget, you have priced their works within your price so you must have had a fair idea of their typical costs.
Your quotation should be in terms of both cost and time, and include an assessment for risk that has a significant decision. Any decision you make and becomes implemented needs to be able to stand up to adjudication in the event they take your assessment to formal dispute.
Your quotation should be in terms of both cost and time, and include an assessment for risk that has a significant decision. Any decision you make and becomes implemented needs to be able to stand up to adjudication in the event they take your assessment to formal dispute.