Hi Karthic
As far as I know FIDIC does not mention concurrent delay specifically.
The other problem is that different delay analysis methods give different results on concurrency.
For instance it is almost impossible to generate true concurrency using the windows method.
Currently the generally accepted rules are these:
1. True concurrency - where two delay events each start on the same day and each affect the same critical path.
Example: The employer cannot grant access to start the works and the contractor's selected piling sub-contractor has gone bust.
Now it all depends who solves their problem first - If the contractor has a new piling sub contractor ready to start but the employer still cannot grant access then the total delay is borne by the employer and no LAD's can be applied but the contractor can only claim costs for the time between when he was ready to start and the employer granted access.
Things start to get more complex if different delay events start on different days and / or affect the critical path differently.
2. Mixed concurrency - over riding employers delay
If the employers delay started first and caused the whole of the delay but the contractors event would have caused delay but for the overiding delay then the contractor gets relief from LAD's but does not get costs for his delay period.
3. Mixed concurrency - over riding contractors delay
If the contractors delay starts first and caused the whole of the delay - and the employers delay does not cause any further delay then the LAD's are applied and no costs awared.
If the contractors delay starts first and caused part of the delay - but the employers delay does cause some further delay then the period of further delay is added to the original completion date and an EoT is awarded for the resulting end date. LAD's are deducted for the remaining delay period. It is not clear if the contractor gets costs for the extended period.
It gets really complex when there are multiple delay events all overlapping.
I hope that is clear.
Best regards
Mike Testro