The Basics of Advanced Scheduling Terminology

Executive Summary. It’s important as a contractor, or even as an owner’s representative, to know a bit more than the basics of scheduling.  Familiarity of some of the terms is helpful regardless of what side of the table you’re on:  Contractor or Owner. 

The terms.  When a project starts to deviate from the schedule, it’s good to know the basics of terminology related to scheduling and claims consulting.  Here’s a head start on some of the terms, basics and beyond:

  • Critical Path – This is likely the most common term in scheduling.  Simply stated critical path is the sequence of activities that must be performed – with zero delay – in order to complete the project.  A critical path has no float, and if any of the activities take longer than stated on the schedule, there is a delay.
  • Quantum -Most of the time this term refers to money – in the claims world it usually has to do with the amount of money a contractor feels he is due from the client.  In terms of scheduling, it is the measurement in number of days of a delay. 
  • ALV and PLVEach of these terms, respectively, stands for Activity-level variance (ALV) and Project-level variance (PLV).  If an activity suffers a twelve (12) calendar day delay which pushes the overall project delay to nine (9) calendar days, the ALV and PLV follow:
    • ALV (Activity-level variance) = 12 calendar days
    • PLV (Project-level variance) = 9 calendar days
  • Knock-on delaysAnother synonymous term to knock-on delays is trickle effect.  As an example, say the drywall installation is delayed. Because painting of the wall comes only after the drywall is hung, we now have a knock-on delay to the interior painting.
  • Float or slack – this is certainly one of the most common terms in scheduling:  float.  It’s also known as slack.  This is the amount of time an activity can be delayed in its completion before the critical path is affected.
  • Force majeure – a delay event out of control, and outside the realm of reasonable contemplation, of both the contractor and owner.  Examples include weather, act of God, labor strikes.  Contractual clauses vary, so be sure to read the language in your contract.
  • Pacing or slow walking – this is a term used to describe contractor-slowed production due to the concurrent existence of the owner’s delay with some other activity.  It can open the door to a contractor’s breach of contract in his duty to treat time of the essence.
  • Disruption – interruption of a contractor’s normal work progress resulting in some level of inefficiency or loss in production. 
  • Recovery – efforts taken on by the contractor to recover from his own delay.
  • No damages for delay – this legal clause takes on many forms, but the premise is that the contractor is precluded from being compensated in delay to his work.  In the public sector they have been difficult to enforce, in the private sector contractors often have a greater battle on their hands.
  • Directed acceleration – an owner’s demand to accelerate the project to recover lost schedule.
  • Constructive acceleration – when an owner refuses to acknowledge and award a contractor-deemed excusable delay to the work and the contractor accelerates at his own volition.

My Story.  These terms are as much claims terms as they are specific to scheduling – scheduling is a subset to a claim. 

Each of these terms may surface in the case of a claim on your project.  I could provide an anecdote on any of these.  In regards specifically to scheduling (versus claims), I’d say that the presentation of disruption in a schedule can be the most costly to both contractors and owners.  If a project is built out of sequence, with several overlapping activities, with additional labor and/or supervision, and/or with a heavy stacking of trades, this can be damming to both parties.  A good scheduler can show this effect to make the case against an owner and help protect a contractor.