If by reason of any accident or fai

If by reason of any accident or failure or other event occurring to, in or in connection with the Works or any part thereof, either during the execution of the Works or during the Defects Liability Period, any remedial or other work or repair shall in the opinion of the Engineer be urgently necessary and the Contractor is unable or unwilling at once to do such work or repair, the Authority may by its own or other workmen do such work or repair as the Engineer may consider necessary. If the work or repair so done by the Authority is work which in the opinion of the Engineer the Contractor was liable to do at his own expense under the Contract all costs and charges properly incurred by the Authority in so doing shall on demand be paid by the Contractor to the Authority or may be deducted by the Authority from any money due or which may become due to the Contractor. Provided always that the Engineer shall as soon after the occurrence of any such emergency as may be reasonably practicable notify the Contractor thereof in writing.