1. Bridge forms critical path (6 months to construct)
Approach Road has 66d of “float”
66d
THE INITIAL PROGRAMME (Carefully planned and resourced)

2. 1st window
VO1
Increased depth: 20d additional excavation
Subcontract award after 25d (5d late)
Paving not commenced due to material shortage
20d delay due to VO1
SITUATION AS AT END OF FEB 07 (Close of First ‘Window’)

3. Events in First “Window” (Jan/Feb)
Day 1: Excavation starts; S/C bids compiled;
Day 10: VO1 issued, increasing the depth of abutment foundations – 20d extra excavation required;
Day 25: Road Subcontract awarded (NB. 5d late);
Day 58 (End of window): (i) Abutments excavation almost completed; (ii) Road paving cannot be sourced (materials shortage)

4. Events in 2nd “Window” (Mar/Apr)
Day 60: Excavation of abutments completed; Day 75: Pavement laying commenced
Day 90: Concreting of abutments completes slowly, taking 30d in total (so a 14d delay);
Day 100: VO2 – major instruction for a further ½km of road, in difficult ground (on piles) – planned at 21d to source piling s/c, 30d to drive 30 piles, 20d to test, 30d to construct new road & drains, and 15d for street furniture. A total duration of 114d is required.
Day 120 (End of window): No further delays, but due to massive VO2, the approach roads are now on the critical path

5. Slow Concreting of Abutments (14d delay)
2nd window
Slow Concreting of Abutments (14d delay)
21d
VO2
New 0.5km of road; in poor ground (on piles)
48d delay; (20d VO1, 14d slow abutments; 14d VO2)
SITUATION AS AT END OF APR 07 (Close of Second ‘Window’)

6. Events in 3rd “Window” (May/Jun)
Day 121: Falsework erectors go on strike for the whole month of May
Day 135: Contractor says that he will mitigate the delay by doubling up resources on the commissioning stage;
Day 160: VO3 – 10 more piles instructed in the new piled approach section, these will take an extra 10 days to complete
Day 181 (End of window): No further delays, but due to the month-long strike, the bridge has become once again more critical than the approach road

7. One month lost due to falsework s/c strike
3rd window
One month lost due to falsework s/c strike
Mitigation: commissioning now only 8d
21d
VO3: Additional piles instructed at new road
VO3
66d delay; (20d VO1, 14d slow abutments; 14d VO2; 25d strike; -7d mitigation)
SITUATION AS AT END OF JUN 07 (Close of Third ‘Window’)

8. Events in 4th “Window” (Jul/Aug)
Day Day 243: Further problems with Falsework erectors – not all were pleased with strike settlement terms, and productivity suffers.
Day 243 (End of window): No further delays; approach road completed bar for commissioning; but the elevated bridge concrete deck only managed completion at the very end of this period. The bridge thus remained more critical than the approach road throughout.

9. SITUATION AS AT END OF AUG 07 (Close of Fourth ‘Window’)
More than one further month lost due to poor falsework s/c productivity
21d
98d delay; (20d VO1, 14d slow abutments; 14d VO2; 25d strike; -7d mitigation; 32d poor falsework productivity)
SITUATION AS AT END OF AUG 07 (Close of Fourth ‘Window’)

10. Events in 5th “Window” (Sep/Oct)
Day 270: VO4, some new road markings and revised drainage causes an extra 10d of work.
Day 289 (End of project): The project completes on 16 October 2007, some 108 days late.
Critical VOs:- VO1=20d, VO2=14d; VO4=10d: Total = 44d

11. New Road marking scheme
5th window
21d
VO4
New Road marking scheme
108d
-108
SITUATION AS AT END OF OCT 07 (Close of Fifth ‘Window’)

12. 20d
14d
10d

13. As-Built Subtracted Analysis
Take the as-built programme, and subtract the delays which the contractor has suffered (which are not to his own default).
This gives rise to a theoretical date, the date on which the contractor would have finished but for the delays
The difference between the ABBF date, and the actual completion date represents the potential entitlement to EOT

14. AS-BUILT BUT-FOR / AS-BUILT SUBTRACTED ANALYSIS
VO1
21d
VO2
VO3
VO4
-108
AS-BUILT BUT-FOR / AS-BUILT SUBTRACTED ANALYSIS

15. AS-BUILT BUT-FOR / AS-BUILT SUBTRACTED ANALYSIS
-78
AS-BUILT BUT-FOR / AS-BUILT SUBTRACTED ANALYSIS

16. As-Built Subtracted Analysis
The “longest path” is favoured
Only the VOs on the longest path feature in the subtraction, irrespective of the contemporary criticality of other VOs
Thus, VO1 (20d) and VO4 (10d) are those which, when subtracted, cause the ABBF date to be collapsed back in time. Thus the potential EOT entitlement here is 30d (cf. 44d in the windows analysis)

17. As-Planned Impacted Analysis
The initial programme (warts and all) is taken, and into it are impacted all of the delays which the contractor has suffered
The impacts are ‘added’ into the initial network; sometimes this is done in ‘real time’, but this causes problems if the delays are caused late due to the contractor’s own problems (e.g. a VO instructed at a late stage merely because of earlier contractor’s delays);

18. THE INITIAL PROGRAMME (Carefully planned and resourced)

19. THE INITIAL PROGRAMME IMPACTED WITH VO1-VO4

20. As-Planned Impacted Analysis
The impacts take no account of progress, or of any of the contractor’s own defaults.
The resultant date is again a theoretical date, perhaps best described as the date for which the contractor would have programmed if it had know about all of the additionally instructed work at the outset;
If the VOs are impacted in chronological order, then they all figure in this example: VO1=20d; VO2=28d*; VO3=10d; VO4=10d: Total = 68d (cf. 30d ABBF, 44d windows analysis)
* Net delay given initial float and the prior occurrence of VO1

21. City Inn v Shepherd Construction [Appeal: 2010]
CONCURRENT DELAY (Lord Carloway)
The initial exercise to be carried out by the architect occurs upon the application of the contractor, who will have requested an extension of time by intimating, under clause 25.2, that the progress of the Works "is being or is likely to be delayed". He will claim that a Relevant Event has been the, or at least a, cause of the delay. The architect then has to decide whether he considers that the completion of the Works is likely to be delayed by a Relevant Event beyond the Completion Date (clauses and 2).

22. City Inn v Shepherd Construction [Appeal: 2010]
CONCURRENT DELAY (Lord Carloway)
This provision is designed to allow the contractor sufficient time to complete the Works, having regard to matters which are not his fault (i.e. Relevant Events). This does not, at least strictly, involve any analysis of competing causes of delay or an assessment of how far other events have, or might have, caused delay beyond the Completion Date. It proceeds, to a large extent, upon a hypothetical assumption that the contract has proceeded, and will proceed, without contractor default. It involves an assessment, on that assumption, of the delay which would have been caused to the Completion Date purely as a result of the Relevant Event.

23. City Inn v Shepherd Construction [Appeal: 2010]
CONCURRENT DELAY (Lord Carloway)
But the exercise remains one of looking at the Relevant Event and the effect it would have had on the original (or already altered) Completion Date. If a Relevant Event occurs (no matter when), the fact that the Works would have been delayed, in any event, because of a contractor default remains irrelevant. In that respect, the view of HHJ Seymour QC in Royal Brompton Hospital NHS Trust v Hammond & Others (No 7) [2001] 76 Con LR 148 (at para 31), that a Relevant Event falls to be disregarded if a pre-existing contractor default would nonetheless have caused the delay, appears to be in error.