delay analysis
TRANSCRIPT
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Modern Delay Analysis
Techniques
Scott Adams BEng LLB PgD LLM CEng MICE FCIArb MAPM MAE
Scott Adams Consultants Ltd.
505 Winfield Commercial Bldg.
6-8 Prat Avenue, TST, HK
Tel: 2312 1708, Fax: 2723 1738
Web: www.scadacon.com.hk
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Modern Delay Analysis
Techniques 1.‘Static’ methods
• Only one network used: Delays added into it, or
subtracted from it – progress not accounted for
2. ‘Dynamic’ methods
• Several networks used, „updated‟ either in real time or
retrospectively – progress accounted for
[AACE International Recommended Practice
No.29R-03 “Forensic Schedule Analysis”: 5-level
taxonomy, giving 8 broad methodologies
described over 105 closely-typed pages]
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Contents
• The Mirant case
• Windows analysis – an example
• Other RDA techniques
• Advantages and disadvantages
• The City Inn Case
• Problems of programming
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Mirant v Ove Arup [2007]
• “Windows analysis, reviewing the course of a
Project month by month, provides an excellent
form of analysis to inform those controlling the
Project what action they need to take to prevent
delay to the Project.”
• “Without such analysis those controlling the
Project may think they know what activities are
on the critical path but it may well appear after a
critical path analysis that they were mistaken.”
Summary observations of HHJ Toulmin at 564:
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Windows Analysis
• “The expert must not only be familiar with
the chronology, he must tell the story in his
report. … Some would say that the
software exercise counts for nothing
unless backed up by the narrative.”
John Marrin QC: Expert Evidence on Delay and
Disruption – The Tribunal’s Perspective
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Windows Analysis
• Example project: Civil Engineering Works
• But - exactly the same programming
principles apply in building works projects
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Windows Analysis
• Example project: Bridge and Approach
Road;
• Start date 01-Jan-07; Date for Completion
30-Jun-07; (6 month project)
• Main Contractor a bridge specialist; but
not a road-works specialist – so this will be
sub-contracted out
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Bridge forms critical
path (6 months to
construct)
THE INITIAL PROGRAMME (Carefully planned and resourced)
Approach Road has
66d of “float”
66d
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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)
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VO1
Increased depth: 20d
additional excavation
Subcontract award
after 25d (5d late)
Paving not commenced
due to material shortage
SITUATION AS AT END OF FEB 07 (Close of First „Window‟)
1st window
20d delay
due to VO1
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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
• Day 120 (End of window): No further delays, but due to
massive VO2, the approach roads are now on the critical
path
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2nd window
SITUATION AS AT END OF APR 07 (Close of Second „Window‟)
Slow Concreting of
Abutments (14d delay)
VO2
New 0.5km of road; in
poor ground (on piles)
48d delay; (20d VO1, 14d
slow abutments; 14d VO2)
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21d
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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
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3rd window
One month lost due to
falsework s/c strike
VO3: Additional piles
instructed at new road
VO3
SITUATION AS AT END OF JUN 07 (Close of Third „Window‟)
66d delay; (20d VO1, 14d slow abutments;
14d VO2; 25d strike; -7d mitigation)
Mitigation:
commissioning
now only 8d 21d
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Events in 4th “Window” (Jul/Aug)
• Day 182 - 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.
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SITUATION AS AT END OF AUG 07 (Close of Fourth „Window‟)
4th
window
More than one further
month lost due to poor
falsework s/c
productivity
98d delay; (20d VO1, 14d slow abutments;
14d VO2; 25d strike; -7d mitigation; 32d
poor falsework productivity)
21d
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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
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-108
5th
window
SITUATION AS AT END OF OCT 07 (Close of Fifth „Window‟) 108d
VO4 New Road marking
scheme
21d
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Jan Feb Mar Apr May Jun Jul Aug Sep Oct
Jan Feb Mar Apr May Jun Jul Aug Sep Oct
-70 -70
2007
Time v Delay Chart
-50 -50
-60 -60
-30 -30
-40 -40
-10 -10
-20 -20
10 10
0 0
30 30
20 20
50 50
40 40
70 70
60 60
90 90
80 80
2007
110 110
100 100
1st window [20d
delay]
2nd window
[48d delay]
3rd window
[66d delay]
4th window [98d
delay]
KEY:
BRIDGE
APPROACH ROAD
VO1VO2
VO3
VO4
S/C issued
late
Lack of paving
materials
Approach Road
construction
completed
Slow abutments
progress
Falseworker
Strike action
Mitigation by
increasing
commissioning
teams
Poor falsework
productivity
Bridge complete
108d late
20d
14d
10d
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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
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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)
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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);
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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
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Advantages & Disadvantages
• The „static‟ analyses (APIP, ABBF) are simple, requiring only two sheets of paper for a „before and after‟ effect;
• But their results are theoretical, there is no account of progress made, no account of changes to the plan, no account of mitigation
• The „windows‟ analysis does take account of such factors, which may account for the warm reception in the Mirant case; but this does come at a cost of complexity, and the programmes must be reliable … also:
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Advantages & Disadvantages
• “Although the status at the start and end of the
window will allow any delay to be quantified it will
not in itself demonstrate the cause or causes of
delay. Analysis of these [intra-window] delaying
events can be carried out by using any method
which is applicable, dependant upon the
activities and the events in question. It may be
appropriate to use a „collapsed as-built‟ or an
„as-planned impacted‟ methodology …”
Lowsley, Linnett “About Time”, p.90
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HK Standard Form (Private Form)
• Upon it becoming reasonably apparent that the
progress of the works is delayed, the MC shall
forthwith give written notice … and if in the opinion of
the Architect the completion of the works is likely to be
or has been delayed beyond the DfC by … [the
various reasons] …then he shall as soon as he is able
to estimate the length of the delay … make a fair and
reasonable extension of time for the completion of the
Works …”
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• Scottish Decision (only of persuasive value in HK)
• JCT-style contract („actual‟ and „likely‟ delay can give rise to EOT)
• Pursuer‟s expert used some form of CPM; Defender‟s expert used an “as-planned vs as-built” chart (not a CPM analysis and seemingly not capable of discerning likely delay)
City Inn v Shepherd
Construction [2007]
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City Inn v Shepherd Construction
[2007]
• “ Consequently I think it necessary to revert to the methods that were in use before computer software came to be used extensively in the programming of complex construction”
• “The older methods are still plainly valid, and if computer-based techniques cannot be used accurately there is no alternative to using older non-computer-based techniques.”
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City Inn v Shepherd Construction
[2007]
• “ … in the type of programme used to carry out
CPM analysis any significant error in the
information fed into the programme can
invalidate the whole analysis … it is easy to
make such errors”
• “That seems to me to invalidate the use of an
as-built CPM analysis to discover after the event
where the critical path lay, at least … where full
electronic records are not available from the
Contractor.”
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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 25.3.1.1 and 2).
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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.
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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.
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Jan Feb Mar Apr May Jun Jul Aug Sep Oct
Jan Feb Mar Apr May Jun Jul Aug Sep Oct
-70 -70
2007
Time v Delay Chart
-50 -50
-60 -60
-30 -30
-40 -40
-10 -10
-20 -20
10 10
0 0
30 30
20 20
50 50
40 40
70 70
60 60
90 90
80 80
2007
110 110
100 100
1st window [20d
delay]
2nd window
[48d delay]
3rd window
[66d delay]
4th window [98d
delay]
KEY:
BRIDGE
APPROACH ROAD
VO1VO2
VO3
VO4
S/C issued
late
Lack of paving
materials
Approach Road
construction
completed
Slow abutments
progress
Falseworker
Strike action
Mitigation by
increasing
commissioning
teams
Poor falsework
productivity
Bridge complete
108d late
20d
28d
10d
10d
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City Inn v Shepherd Construction
[Appeal: 2010]
• CONCURRENT DELAY (Lord Carloway)
• VO1 = 20 days;
• VO2 = 28 days;
• VO3 = 10 days;
• VO4 = 10 days
(So the “Lord Carloway approach” might
give a 68 day entitlement – the same as
the as-planned-impacted in this example).
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Common Programming and
Planning Problems
• Planner often a junior/inexperienced staff member;
• No resources are considered in programmes;
• Programmes are bar-charts, with no logic;
• The „concertina‟ effect – programme depicts completion on time, even after several delays have occurred;
• “OP = PC”;
• PC certified for commercial (secret) reasons;
• The programme becomes a commercial or political document, not a project management tool