Scheduling and Delay Terminology

This is the third blog post in a six-part series that defines terms commonly used in Engineering, Procurement, and Construction (EPC) project management, construction management, and claims. The first post defined language related to costs, damages, and cost estimating, and the second post addressed construction labor and loss of productivity. This third blog post covers scheduling and delay, and future posts will focus on claim and contract types, plus project and construction management.

Acceleration – Acceleration of a construction project occurs when the construction schedule for the project, or a portion of the project, is shorter than what would be required using normal sequences of construction on a normal working schedule. If the contractor agreed to a short schedule, it may be responsible for the acceleration costs unless the owner caused critical path delay to the contractor’s work and did not provide a time extension. Also, compensable acceleration may occur when the contractor is directed to perform the work in a shorter time period than it believes is allowed under the contract. Compensable acceleration can also occur when additional work is added through contract changes or constructive changes, but additional time for performance is not granted. If both parties are responsible for delays to the work that requires acceleration, then it may be necessary to allocate the acceleration costs based on an allocation of delay responsibility and other contractual issues, such as but not limited to the owner’s responses to time extension requests by the contractor.

Activity – Component of the Scope of Work that the schedule expresses. Also may be referred to as a “task.”

Bar Chart – A scheduling tool (also called a Gantt chart) that shows the time span of each activity as a line, the ends of which correspond to the start and finish dates of the activity.

Baseline – A quantitative definition of cost, schedule, and scope performance that serves as a base or standard for measurement and control during the performance of an effort. The established plan against which the status of resources and the work effort are measured, assessed, and controlled. Once established, baselines are subject to change control procedures.

Concurrent Delay – Concurrent delays are two or more delays that occur, at least to some degree, concurrently; that is, during the same period of time. The term of art is used in construction law to refer to a situation when a compensable delay and a noncompensable delay occur at the same time or in overlapping time periods. For example, the term would apply when a contractor cannot commence work on the second phase of a project because the owner has failed to obtain a necessary right-of-way, and simultaneously the contractor cannot commence the second phase because of its failure to timely complete precedent work in the first phase.

Concurrent delay creates interesting legal issues about assessing responsibility for overall project delay. This issue may be further complicated because: the delay periods may be of different lengths; the delay periods may be of the same or different lengths but not totally concurrent; and the delays may be of identical lengths and totally concurrent but have different impacts in terms of the number and types of work activities they affect and the severity of that impact.

Critical Activities – Those activities in the schedule network for which float values are less than or equal to zero days. Zero-float-day activities must be completed at the calculated late finish schedule time to prevent expansion of the total project duration and delay to the project completion date. Activities with negative float indicate that project completion is already delayed from the scheduled completion date, and the activity path with the most negative float is now the critical path to project completion and any delay to that path will delay the completion date even further.

Critical Path – The portion of the schedule that is comprised of scheduled activities for which any schedule delay may be expected to cause a corresponding delay in the overall project completion or end product.

Critical Path Method (CPM) – The methodology/management technique that makes analytical use of information regarding the critical path and other sequential paths through the network. A logical, analytical, network-based scheduling tool that demonstrates the schedule paths and constraints toward accomplishment of specified objectives and evaluates the allowable and expected time spans for the activities contained therein. Activities that, when delayed, impact the project completion date are critical and said to be on the critical path.

Dummy Activity – In the Arrow Diagramming Method (ADM) format only, a zero-duration activity used to connect two or more related activities.

Duration – The period of time that is required to complete an activity.

Early Completion Prevented – Actions or inactions of the owner that prevent the contractor from completing the project, or any part of the project, on the date that the contractor planned, when and if that date is before the established contract completion date. To make a claim for delay to early completion, the contractor may need to establish that it notified the owner of its intent to complete the project early, and that its plan was reasonable.

Early Finish (EF) – In a network diagram schedule, the earliest time an activity can be completed.

Early Start (ES) – In a network diagram schedule, the earliest time an activity can be started.

Float – The amount of time that an activity may be delayed from its early start without delaying the project finish date. Float is a mathematical calculation and can change as the project progresses and changes are made to the project plan. Also called slack, total float, and path float. See also free float.

Free Float (FF) – The amount of time an activity can be delayed from its earliest start time to the point where it interferes with the earliest start time of its succeeding activity.

Late Finish (LF) – In a network diagram schedule, the latest time an activity can be finished.

Late Start (LS) – In a network diagram schedule, the latest time an activity can be started.

Level of Detail – The successively lower elements within the hierarchy, with each element being a further breakout of the next higher element.

Leveling Resources – The technique of scheduling the use of resources in a way that avoids wide fluctuations in resource demand. Resources generally cost less and are more easily managed if they are scheduled at a steady rate.

Logic Network – A diagram used to identify the sequence and relationships of the Critical Path Method (CPM) schedule activities. The logic network complements and supports the work breakdown structure and establishes and gives direction to the work packages and tasks.

Master Schedule – A master schedule is compiled to show (1) the total time available for the entire job if it must be finished by a certain time, and (2) how the various portions of the job are to be scheduled.

Milestone Activity – An important or critical event and/or activity that must occur in the project cycle to achieve the project objectives.

Negative Float – In a Critical Path Method (CPM) network, if a condition exists wherein the early finish time is later than the late finish time for an activity or series of activities, the condition results in negative float values. Negative float indicates project delay.

Out-of-Sequence Work – If work is not planned in a logical manner, crews are moved around excessively and productivity declines. If the contractor can demonstrate that the owner is responsible for the need to perform work out of sequence, the contractor may be entitled to recover its loss-of-productivity costs for such problems.

Planning – Planning precedes scheduling and is more general in its view of the project. The purpose of planning is to identify and set forth the overall objectives of the project.

Planning Packages – The element of a cost account containing scope, schedule, and budget for those efforts in the far term, where detail planning of those efforts is unpractical. Scope is understood but not clearly defined.

Program – An organized set of activities directed toward a common purpose or goal undertaken or proposed in support of an assigned mission. It is characterized by a strategy for accomplishing a definite objective or objectives that identifies the means of accomplishment, particularly in qualitative terms with respect to work force, material, and facility requirements. Programs are typically made up of technology-based activities, projects, and supporting operations.

Program Evaluation Review Technique – The Program (or Project) Evaluation and Review Technique, commonly abbreviated PERT, is a model for project management designed to analyze and represent the tasks involved in completing a given project. PERT was developed primarily to simplify the planning and scheduling of large and complex projects. It was able to incorporate uncertainty by making it possible to schedule a project while not knowing precisely the details and durations of all the activities. It is more of an event-oriented technique rather than start- and completion-oriented and is used more in R&D-type projects where time, rather than cost, is the major factor. PERT uses deterministic networks with mean durations derived from a specialized version of the beta distribution; the mean duration is set at expected time: the best estimate of the time required to accomplish a task, assuming everything proceeds as normal (the implication being that the expected time is the average time the task would require if the task were repeated on a number of occasions over an extended period of time). PERT uses deterministic analysis of a network with mean durations derived from a special, simplified version of the beta distribution. The mean duration in PERT is found with the formula T = (L + 4ML + H) ÷ 6, where T is duration and L, ML, and H are the least, most likely, and highest durations assessed by subject matter experts.

Project Baseline Schedule – The configuration-controlled, project schedule supporting the contractual and internal deliveries of the project. This document, once approved and resource-loaded, becomes the basis for the performance measurement baseline.

Relationship – A relationship of an event to a succeeding activity in which the activity may not start until the event preceding it has occurred. The term “constraint” is also used to indicate a relationship of an activity to a succeeding event in which the event cannot occur until all activities preceding it have been completed.

Schedule Baseline – The time-phased plan with a logical sequence of interdependent activities, milestones, and events necessary to complete the project. The schedule baseline must be formally changed during the execution of the project when required.

Schedule Contingency – The duration of time calculated that is in addition to the total project duration calculated using activities and logical relationships. This duration is in addition to the time required to complete all activities in the project schedule. The schedule contingency is managed by the project manager and may be applied as deemed necessary to maintain the schedule baseline.

Scheduling – Scheduling establishes the intermediate goals that, if accomplished, will result naturally in the achievement of the stated objectives. Planning a project involves scope reviews, contract completeness reviews, resource planning, work schedule assignments, calendars, facility utilization planning, management methods, organizational structures, capital expenditure planning, contracts, procurement, and more.

Scheduling Difficulties/Failure to Coordinate the Work (Coordination Problems) – Failure of the contractor to properly sequence or coordinate work, adhere to project schedule, timely update schedule, or provide accurate scheduling information; illogical work scheduling or sequencing; manipulation of schedule that stops, delays, disrupts, or hinders the contractor’s ongoing or planned work. The contractor is typically responsible for such scheduling and coordination of its labor, vendors, and subcontractors, and as such, is responsible for the delays and disruptions that result therefrom. If, however, the owner is contractually responsible for such scheduling and coordination, the contractor may be entitled to recover its delay and disruption costs if the activities in its schedule that such lack of scheduling and coordination affected were on the critical path of the project schedule at the time that the problems occurred and if the contractor was not responsible for other concurrent delays at that time.

SCL Protocol – The Society of Construction Law Delay and Disruption Protocol (SCL Protocol) is a document that the Society of Construction Law last published as a Second Edition in February 2017.

The object of the Protocol is to provide useful guidance on some of the common delay and disruption issues that arise on construction projects, where one party wishes to recover from the other an extension of time (EOT) and/or compensation for the additional time spent and the resources used to complete the project. The purpose of the Protocol is to provide a means by which the parties can resolve these matters and avoid unnecessary disputes. A focus of the Protocol therefore is the provision of practical and principled guidance on proportionate measures for dealing with delay and disruption issues that can be applied in relation to all projects, regardless of complexity or scale, to avoid disputes and, where disputes are unavoidable, to limit the costs of those disputes. On certain issues, the Protocol identifies various options, with the choice of the most appropriate being dependent on the nature, scale and level of complexity of a particular project and the circumstances in which the issue is being considered. On other issues, the Protocol makes a recommendation as to the most appropriate course of action, should that be available.¹

Subcontractor Delay – Actions or inactions of a subcontractor that stop, delay, disrupt, or hinder the prime contractor’s ongoing or planned work. Delays and disruptions by subcontractors are usually the contractor’s responsibility unless the owner caused such problems.

Total Float (TF) – See Float.

Unusually Severe Weather – Weather conditions that deviate substantially from the norm, average, or reasonably expected weather for the particular locality of the project and the current season of the year. Deviations may take the form of otherwise normal conditions, such as rain, snow, or extreme temperatures that persist for an unusually long period. A contractor may be able to receive a time extension for unusually severe weather if the work that such weather conditions affected was on the critical path of the project when the weather occurred. Depending on the existence of contractual provisions stating otherwise, a contractor may be able to recover its increased direct and time-related costs that result from unusually severe weather, and recovery of time-related costs also depends on whether the contractor was responsible for other concurrent delays at that time.

¹      SCL Protocol, p. 1.

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