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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

www.scadacon.com.hkN am e D urTotalfloat

2007Jan Feb M ar Apr M ay Jun J

BRIDGE

Excavate Foundations

C oncrete Abutm ents

Fa lsew k; concre te D eck

L ighting and Furn itu re

APPROACH ROAD

Subcontract R oadw orks

Excavate R oad (1km )

Lay dra ins, paving (1km )

S treet ligh ting insta lla tion

COMPLETION

T&C L ights & D ra ins

Pro ject End D ate

40d

16d

80d

30d

20d

30d

50d

30d

15d

66d

66d

66d

66d

20d

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)

www.scadacon.com.hkLine N am e D ur Tota lfloat

2007Jan Feb Mar Apr May Jun Jul

1

2

3

4

5

6

7

8

9

10

11

BRIDGE

In itia l excava tion w orkscope

VO 1 increased dep th

C oncre te Abu tm ents


L igh ting and Furn itu re

APPROACH ROAD


Excava te R oad (1km )

Lay d ra ins, paving (1km )

S tree t ligh ting insta lla tion

COMPLETION

T&C L igh ts & D ra ins

P ro ject End D ate

40d

20d

16d

80d

30d

25d

48d

50d

30d

15d

128d

58d

58d

-20d

20d

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

www.scadacon.com.hkNam e DurTotalfloat

2007Jan Feb M ar Apr M ay Jun Jul Aug

BRIDGE

In itia l excavation workscope

VO 1 increased depth

Concrete Abutm ents

Falsewk; concrete Deck

Lighting and Furniture

APPROACH ROAD

Subcontract Roadworks

Excavate Road (1km )


S treet lighting insta lla tion

VO 2 Appoint p iling S /C

VO 2 P iling + test

VO 2 Lay dra ins, paving

VO 2 Lighting + Furn iture

COM PLETION

T&C Lights & D rains

Project End Date

40d

20d

30d

79d

30d

25d

63d

60d

30d

20d5h

50d

30d

15d

15d

14d

14d

33d

43d

-48d

20d

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

www.scadacon.com.hkNam e DurTotalfloat

2007Jan Feb M ar Apr M ay Jun Jul Aug S

BRIDGE


VO 1 increased depth

Concrete Abutm ents


Lighting and Furn iture

APPROACH ROAD



Lay dra ins, pav ing (1km )

S treet lighting insta lla tion

VO 2 Appoint p iling S /C

VO 2 P iling + test

VO 2 Lay dra ins, pav ing

VO 2 L ighting + Furn iture

COM PLETION

T&C Lights & D ra ins

P ro ject End Date

40d

20d

30d

85d

30d

25d

63d

60d

30d

20d5h

60d

30d

15d

8d

14d

14d

-66d

20d

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 8d21d

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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.

www.scadacon.com.hkN am e D ur Tota lfloat

2007Jan Feb M ar Apr M ay Jun Jul Aug Sep O

BRIDG E

In itia l excavation w orkscope

V O 1 increased depth

C oncrete A butm ents

Falsew k; concrete D eck


APPRO ACH RO AD

S ubcontract R oadw orks

E xcavate R oad (1km )

Lay drains, paving (1km )

S treet lighting installation

V O 2 A ppoint p iling S /C

V O 2 P iling + test

V O 2 Lay drains, paving

V O 2 Lighting + Furniture

CO M PLETIO N

T& C Lights & D rains

P roject E nd D ate

40d

20d

30d

117d

30d

25d

63d

60d

30d

20d 5h

60d

30d

15d

8d

-98d

20d

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


2007Jan Feb M ar Apr M ay Jun Jul Aug Sep Oct

BRIDG E






APPRO ACH RO AD









CO M PLETIO N


P roject E nd D ate

40d

20d

30d

117d

30d

25d

63d

60d

30d

20d 5h

60d

30d

15d

18d

20d

-108

5th window

SITUATION AS AT END OF OCT 07 (Close of Fifth ‘Window’) 108d

VO4New 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 1001st 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


2007Jan Feb M ar Apr M ay Jun Jul Aug Sep Oct

BRIDG E






APPRO ACH RO AD









CO M PLETIO N


P roject E nd D ate

40d

20d

30d

117d

30d

25d

63d

60d

30d

20d 5h

60d

30d

15d

18d

20d

AS-BUILT BUT-FOR / AS-BUILT SUBTRACTED ANALYSIS

VO2

VO3

VO1

VO4-108

21d

www.scadacon.com.hkN am e D urTota lfloat

2007Jan Feb Mar Apr May Jun Jul Aug Sep Oct

BRIDGE


Concrete Abutm ents



APPROACH ROAD




Street lighting insta lla tion

COMPLETION

T&C L ights & D ra ins

As-Built-But-For Date

Com pletion Date

40d

30d

117d

30d

25d

63d

60d

30d

8d

-14d

20d

AS-BUILT BUT-FOR / AS-BUILT SUBTRACTED ANALYSIS

-78

30d

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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);

www.scadacon.com.hkN am e D ur Totalfloat

2007Jan Feb Mar Apr May Jun Jul Aug Sep Oct N

BRIDGE

In itia l excava tion w orkscope

C oncre te Abu tm ents


L igh ting and Furn itu re

APPROACH ROAD

Subcon tract R oadw orks

Excava te R oad (1km )

Lay d ra ins, pav ing (1km )

S tree t ligh ting insta lla tion

COMPLETION

T&C L igh ts & D ra ins

P ro ject End D ate

40d

16d

80d

30d

20d

30d

50d

30d

15d

66d

66d

66d

66d

20d

THE INITIAL PROGRAMME (Carefully planned and resourced)

www.scadacon.com.hkLine N am e D urTota lfloat

2007Jan Feb M ar Apr M ay Jun Jul Aug S

1

2

3

4

5

6

7

8

9

10

11

BRIDGE

Excavation incl VO 1

C oncrete Abutm ents



APPROACH ROAD


Excavate R oad (1km )


Street lighting insta lla tion

VO 2 & VO 3

COMPLETION

T&C L ights & D ra ins & VO 4

Pro ject End D ate

60d

16d

80d

30d

20d

30d

50d

30d

126d

25d

39d

39d

39d

39d

125d

125d

125d

125d

-69d

20d

VO1

VO2, VO3

VO4

-68d

THE INITIAL PROGRAMME IMPACTED WITH VO1-VO4

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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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• “ 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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• “ … 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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• 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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• 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 1001st 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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• 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

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The “Magic Circle”

Work to that programme until

something occurs which makes it

impossible

Examine and quantify the effects on the programme

Produce a viable, working programme

with full reasons for all revision(s)

www.scadacon.com.hk modern delay analysis techniques scott adams beng llb pgd llm ceng mice fciarb...

Documents

d delay day

d strike

d late day

d of float

d slow abutments

d extra excavation

d delay vo2 new

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