Delay Analysis & AoA schedules

Basics of DelaysWhat is a Delay?Act or event which extends time required to perform or complete work of the contractWho causes delay?OwnerContractorNeither (Force Majeure)Both

Categories of DelaysIndependent DelaysSerial DelaysConcurrent Delays

Types of DelaysFloat DelaysCompletion DelaysInexcusable DelaysNon-Compensable DelaysExcusable DelaysConcurrent DelaysCompensable Delays

Inexcusable DelaysUsed in reference to delays caused by contractors, subs or vendors that delay the projectExamplesFailure to properly man projectFailure to submit documents on timeFailure to coordinate equipment, material deliveriesPoor planning and mismanagementContractor is often asked to pay damages (LDs)

Excusable Delays - 1Non CompensableUnforeseen events that are not the fault of the owners or the contractorsE.g.Acts of GodFires, StrikesPolitical EventsUsually only Time implicationsForce Majeure clauses in contracts decide how to deal with these delays

Excusable Delays - 2CompensableDelays caused by owner or for which owner has accepted liabilityE.g.Change OrdersDelayed responsesWork SuspensionsTime and Cost implicationsClauses in contracts decide how to deal with these delaysNo Damage for Delays clauses may also be present

Concurrent DelaysOwner and Contractor both delay the same activity or activities in the same timeframeMultiple Delays to activities on parallel Critical Paths within same time-frameExampleChange order coinciding with late equipment deliveryLate response to an RFI at the same time as a strike

Concurrent Delays

Pacing DelayContractor A is delayedTherefore Contractor B slows down work on parallel Activities

Contractors have a legal right to slow down!

Key Requirement for Delay AnalysisA Network Schedule that isCompleteWith Reliable InformationIs ApprovedReflects the Intended PlanIs not manipulated (by loading activities)Is Constantly Updated

Network Schedule TipsShould be prepared by, or in consultation with the contractorShould have inputs fromContract DocumentsProject Manager, EstimatorSuperintendents and SubcontractorsClients and ArchitectsIterative, Negotiated, Inclusive Process

Delay Analysis TechniquesFloat Analysis

As-Built Analysis

As-Planned Analysis

Concurrent Delay Analysis

Window/Snapshot Method

1. Float AnalysisIndependent Float belongs to the activityTF, FF belong to a chainProportion Float according to Activity DurationDetermine delays and effect on critical paths

As Built AnalysisCreate final As Built scheduleCompare with As Planned scheduleCalculate Difference this is Delay owed by the other sideFind events to explain these differences

As Planned AnalysisCreate As-Planned vs. As-Built schedulesDetermine delay events (caused by the other side)Add these events, re-calculate scheduleDetermine Time extension, compensation owed etc

Concurrent AnalysisA (5 days)B (7 days) - CriticalA (8 days)B (9 days) - CriticalAs PlannedAs BuiltOwner caused delay= 3 daysContractor caused delay= 2 daysTotal Contractor Liability = 1 day

Concurrent AnalysisCreate As-Planned and As-Built schedulesEstimate Critical Path DelaySubtract concurrent owner-caused or unforeseen delaysUse the remainder to apportion time extensions or costs

Choosing a Delay Analysis MethodDelay Analysis is still an art not a scienceDepends on time availableSnapshot method takes too longDepends on data availableDepends on accuracy desiredAs Planned and As Built methods are quick but inaccurate

AoA AnalysisNodesMilestones=LinksActivities=A12Excavate3 DaysConstruction Network

Criteria for creation of AoA NetworksRepresents Activities on Arrows with Start/Finish milestonesEstimate Activity Duration and represent it on the arrowEnsure each activity has a unique I and jnode Create artificial restraintsSolve the Network

Lets Create an AoA Network for the Following activities

AoA Diagram

Solving the Network101216222628142418200Start11A5F5I3K7D3 B 17J19 H5 G9 E 9C

Forward Pass Early Event Times101216222628142418200Start11A5F5I3K7D3 B 17J19 H5 G9 E 9C031192016113740

Backward Pass Late Event Times101216222628142418200Start11A5F5I3K7D3 B 17J19 H5 G9 E 9C03119201611374040371820321118013

Solving the Network10-12-16-24-26-28 is the critical pathCalculate ES of each activityEarly Event Time of i NodeCalculate EF of each activityES + DurationCalculate LF of each ActivityLate Event Time of j NodeCalculate LS of each ActivityLF DurationCalculate Floats, Critical Path

Convert to PDM

Thank You

Plans are usually made with the unlimited resource assumptionFloat Consumption delays typically do not impact overall schedule and often do not result in extra costs or time extensions. However, there could be cases where these activities can be claimed as delays that result in extra overhead costs or equipment rental costs etc

These usually result in time extensions but no cost implicationsSome times if events are not explicitly in Force Majeure, they can lead to claimsThese usually result in time extensions AND in cost implicationsSome times if events are not explicitly in Force Majeure, they can lead to claimsThis is too simplistic a methodThis is slightly more scientific but omits concurrent delays and cause and effect situationsSame example from text bookDotted lines show logical and not physical constraints