Legal literature and arbitration practice regarding concurrent delays (parallel delays) establish that a concurrent delay entitles the employer as well as the contractor to an extension of time while precluding the parties’ potential entitlement to delay costs. The legal position is in agreement with the Malmaison doctrine known from English law.
Due to the legal position in case of concurrent delays, it is assessed in relation to acceleration that the contractor cannot fully recover the contractor’s acceleration costs if it is at all possible to recover anything. To the best of our knowledge, the most reasonable solution would be for the contractor’s acceleration claims in those cases to be deducted from the costs which a potential, extended construction time would have caused the parties if the contractor had not accelerated.
Contrary to concurrent delays, delay costs, thus also acceleration costs, can be fully recovered in case of reflective delays.