Project Planning Glossary

Contents

Primavera P6

Primavera P6 (Oracle Primavera P6 Enterprise Project Portfolio Management) is the industry-standard scheduling software used to plan, manage, and control complex projects. It is widely adopted across construction, infrastructure, oil and gas, and defence sectors, particularly on large-scale programmes where multiple stakeholders require a single source of scheduling truth.

P6 supports resource loading, cost integration, baseline management, and earned value analysis, making it the tool of choice for projects where contractual compliance and robust programme management are essential.

Oracle Primavera Cloud (OPC)

Oracle Primavera Cloud (OPC) is Oracle's cloud-based project portfolio management platform, designed as the successor to on-premise Primavera P6. It combines scheduling, risk analysis, portfolio management, and lean task management in a single browser-based environment.

Unlike traditional P6, OPC requires no local installation or database infrastructure, offering real-time collaboration and integrated analytics. Organisations are increasingly adopting OPC for its scalability and reduced IT overhead, though many continue to run P6 alongside it during transition.

Critical Path Method (CPM)

The Critical Path Method (CPM) is a scheduling technique that identifies the longest sequence of dependent activities through a project network, determining the shortest possible project duration. By calculating early and late start and finish dates for every activity, CPM reveals which tasks have zero float and therefore directly control the completion date.

It is the foundational methodology behind Primavera P6 and virtually all modern scheduling tools, and understanding the critical path is essential for effective delay analysis and programme recovery.

Critical Path

The critical path is the longest continuous chain of logically linked activities through a schedule, from project start to project finish. Any delay to an activity on the critical path will directly delay the project completion date, because these activities have zero total float.

Identifying and monitoring the critical path is fundamental to effective project management, as it tells the project team exactly where to focus resources and management attention to protect the end date.

Float (Total Float, Free Float, Terminal Float)

Float (also called slack) is the amount of time an activity can be delayed without affecting downstream dates. Total float measures how long an activity can slip before delaying the project completion date. Free float measures how long an activity can slip before delaying the start of any immediate successor. Terminal float is the difference between the scheduled completion and the contractual or imposed finish date.

Under NEC4 contracts, float is typically treated as belonging to the project rather than any single party, making accurate float reporting commercially significant.

Baseline Schedule

A baseline schedule is the approved, time-stamped version of the project programme against which all future progress and performance are measured. Once accepted by the client or contract administrator, the baseline becomes the benchmark for tracking delays, assessing variations, and calculating earned value.

Commercially, the baseline is a critical document because it establishes the contractor's planned sequence and timing, forming the foundation for any delay analysis, extension of time claims, or compensation event assessments.

Integrated Master Schedule (IMS)

An Integrated Master Schedule (IMS) is a comprehensive, resource-loaded schedule that consolidates all project activities, milestones, and deliverables across multiple work streams, contractors, and disciplines into a single programme. It is commonly used on large defence, aerospace, and infrastructure programmes where coordination between numerous parties is essential.

The IMS provides a single view of the entire programme, enabling senior management to identify cross-programme dependencies, resource conflicts, and critical path interactions that would not be visible in individual contractor schedules.

Work Breakdown Structure (WBS)

A Work Breakdown Structure (WBS) is a hierarchical decomposition of a project into progressively smaller, manageable components. In Primavera P6, the WBS provides the organisational framework under which activities are grouped, enabling structured reporting, cost aggregation, and earned value analysis at multiple levels.

A well-designed WBS ensures that every element of project scope is captured, assigned, and trackable, and it typically mirrors the project's contractual or organisational structure.

Activity

An activity is the fundamental building block of a schedule in Primavera P6. Each activity represents a discrete piece of work with a defined duration, start date, finish date, and logical relationships to other activities.

Activities can be task-dependent (duration driven by the calendar), resource-dependent (duration driven by resource availability), or level-of-effort (spanning the duration of related activities). Properly defined activities with clear scope, appropriate durations, and correct logic links are the foundation of a reliable, maintainable programme.

Logic Links / Dependencies (FS, FF, SS, SF)

Logic links (also called dependencies or relationships) define the sequencing constraints between activities in a schedule. There are four relationship types: Finish-to-Start (FS), where the successor cannot start until the predecessor finishes, which is the most common and generally preferred type; Start-to-Start (SS), where the successor cannot start until the predecessor starts; Finish-to-Finish (FF), where the successor cannot finish until the predecessor finishes; and Start-to-Finish (SF), where the successor cannot finish until the predecessor starts, which is rarely used.

Correct logic is critical to producing a valid critical path and reliable schedule forecasts.

Lag and Lead

Lag is a delay applied to a logic link, adding waiting time between the predecessor and successor activities (for example, a 7-day lag on a Finish-to-Start relationship to allow concrete curing time). Lead is a negative lag that allows a successor to start before the predecessor's relationship condition is fully met, effectively overlapping activities.

While lag has legitimate uses for representing physical constraints, excessive or unjustified lag is a common schedule quality issue, as it can mask missing activities and distort the critical path. Most schedule health checks flag high lag values as a concern.

Resource Loading

Resource loading is the process of assigning labour, equipment, and material resources to schedule activities, specifying the type and quantity of resources required for each task. In Primavera P6, resource loading enables the generation of resource histograms, S-curves, and cost profiles, and it supports resource levelling to resolve over-allocations.

Resource-loaded schedules are increasingly required under contracts such as NEC4, where demonstrating adequate resourcing is part of the accepted programme requirements.

Schedule Health Check

A schedule health check is a systematic assessment of a project programme against industry-standard metrics and best practices, typically evaluating logic completeness, constraint usage, float distribution, lag values, activity durations, critical path validity, and resource loading. It identifies weaknesses that could undermine the schedule's reliability as a forecasting and contract management tool.

Planned Limited offers a free schedule health check tool that analyses uploaded P6 XER files against the DCMA 14-Point Assessment and additional quality metrics, providing an instant report with actionable recommendations.

Earned Value Management (EVM)

Earned Value Management (EVM) is a project controls methodology that integrates scope, schedule, and cost data to provide objective measures of project performance and forecasting. The core metrics include Planned Value (PV), Earned Value (EV), and Actual Cost (AC), from which key performance indicators such as Schedule Performance Index (SPI), Cost Performance Index (CPI), and Estimate at Completion (EAC) are derived.

EVM enables project managers and sponsors to identify schedule and cost variances early, forecast final costs with data-driven confidence, and make informed decisions about corrective actions.

Schedule Performance Index (SPI)

The Schedule Performance Index (SPI) is an earned value metric calculated as SPI = Earned Value (EV) / Planned Value (PV). An SPI of 1.0 means the project is exactly on schedule; below 1.0 indicates the project is behind schedule; above 1.0 means ahead of schedule.

For example, an SPI of 0.85 means the project has only completed 85% of the work it was planned to have completed by the reporting date. SPI is a powerful early warning indicator and is widely used in project controls reporting to trend schedule performance over time.

Cost Performance Index (CPI)

The Cost Performance Index (CPI) is an earned value metric calculated as CPI = Earned Value (EV) / Actual Cost (AC). A CPI of 1.0 means the project is spending exactly as planned for the work completed; below 1.0 indicates cost overrun; above 1.0 means the project is under budget.

Research consistently shows that once a project's CPI falls below approximately 0.8, it very rarely recovers, making CPI one of the most reliable predictors of final project cost performance.

Estimate at Completion (EAC)

Estimate at Completion (EAC) is the projected total cost of the project at completion, calculated using current performance data. The most common formula is EAC = Budget at Completion (BAC) / CPI, which assumes current cost performance trends will continue. Alternative formulations incorporate both CPI and SPI for a blended forecast.

EAC provides decision-makers with a data-driven forecast of final outturn cost, enabling timely intervention if the project is trending towards overrun.

S-Curve

An S-curve is a graphical representation of cumulative project data (typically cost, hours, or progress) plotted against time, producing a characteristic S-shaped curve that reflects the typical pattern of slow initial mobilisation, rapid mid-project execution, and tapering activity during closeout.

S-curves are used to compare planned progress against actual performance and earned value, making deviations immediately visible. They are a staple of project controls reporting and are particularly useful for communicating programme status to senior stakeholders.

Schedule Risk Analysis (QSRA)

A Quantitative Schedule Risk Analysis (QSRA) is a technique that applies probabilistic modelling, typically Monte Carlo simulation, to a project schedule to quantify the range of possible completion dates and their associated confidence levels. Rather than relying on a single deterministic end date, a QSRA assigns probability distributions (three-point estimates) to activity durations and risk events, then runs thousands of iterations to produce a probability distribution of project completion dates.

This enables project teams and sponsors to understand the likelihood of achieving target dates and to allocate appropriate contingency.

Monte Carlo Simulation

Monte Carlo simulation is a statistical technique used in schedule risk analysis that runs thousands of iterations of a project schedule, each time randomly sampling activity durations from their assigned probability distributions. The aggregated results produce a probability distribution of possible project completion dates, showing the likelihood of finishing by any given date.

For example, a Monte Carlo analysis might show that there is a 50% chance of completing by 1 March and an 80% chance of completing by 15 April. This approach is far more informative than a single deterministic date and is standard practice for major infrastructure and capital projects.

Three-Point Estimate

A three-point estimate uses three duration values for each activity: optimistic (best-case), most likely (expected), and pessimistic (worst-case). These three values define a probability distribution, typically triangular or beta (PERT), that captures the inherent uncertainty in activity durations.

Three-point estimates are the primary input to Monte Carlo simulation for schedule risk analysis. The quality of a QSRA depends heavily on the realism of these estimates, which should be informed by subject-matter experts and, where available, historical project data.

P50 / P80 / P90 Confidence Levels

P50, P80, and P90 are probabilistic confidence levels derived from Monte Carlo simulation, representing the dates or costs at which there is a 50%, 80%, or 90% chance of the project completing within that value. P50 means there is an equal chance of finishing earlier or later than that date.

P80 is commonly used as the basis for setting project contingency and contract completion dates, as it provides reasonable confidence without excessive conservatism. Clients and sponsors often require P80 or P90 dates when approving budgets and schedules for major capital projects.

NEC4 Accepted Programme

Under NEC4 (New Engineering Contract 4th Edition), the Accepted Programme is the contractor's programme that has been formally accepted by the Project Manager under Clause 31. It must show the planned sequence of work, float, time risk allowances, order and timing of work of others, key dates, and other information specified in the contract.

The Accepted Programme is a live document that must be updated regularly and resubmitted for acceptance. It plays a central commercial role because it is used to assess the time impact of compensation events, and failure to maintain an accepted programme can prejudice the contractor's ability to claim extensions of time.

Compensation Event

A compensation event is a contractual mechanism under NEC3 and NEC4 contracts by which the contractor is compensated for events that are not their fault and that change the scope, timing, or cost of the works. Compensation events are assessed based on their impact on the Accepted Programme and the defined cost of the work.

Examples include changes to the works information, site conditions differing from those described, and client-caused delays. The assessment requires a robust programme demonstrating the impact, making accurate Primavera P6 scheduling essential to the commercial process.

Delay Analysis

Delay analysis is the forensic examination of a project schedule to determine the causes, extent, and responsibility for delays to the completion date. The main methodologies include Time Impact Analysis (TIA), which models each delay event prospectively into the schedule; As-Planned vs As-Built, which compares the original plan against what actually happened; and Windows Analysis, which divides the project into time periods and analyses delay in each window.

The choice of methodology depends on the contract, the available records, and the quality of the programme data. Reliable delay analysis requires a well-maintained, logically linked schedule with regular progress updates.

Extension of Time (EOT)

An Extension of Time (EOT) is a contractual entitlement that extends the completion date due to qualifying delay events, relieving the contractor from liquidated damages for the period of the extension. EOT claims must typically demonstrate that the delay event affected the critical path and that the contractor took reasonable steps to mitigate the impact.

The assessment is grounded in the project programme, and a properly maintained, baseline schedule in Primavera P6 with contemporaneous updates is essential evidence for substantiating or defending an EOT claim.

Planning Consultant

A planning consultant (also called a scheduling consultant or project planner) is a specialist who develops, maintains, and analyses project programmes, typically using Primavera P6 or Oracle Primavera Cloud. Their responsibilities include building and updating schedules, progress reporting, critical path analysis, delay analysis, resource loading, and advising on programme strategy.

Organisations engage planning consultants when they need specialist scheduling expertise that is not available in-house, during peak workload periods, or for specific deliverables such as tender programmes, baseline schedules, or delay claims.

Project Controls Manager

A Project Controls Manager oversees the integrated planning, cost control, risk management, and performance reporting functions on a project or programme. They are responsible for establishing and maintaining the project controls framework, including scheduling standards, earned value systems, change management processes, and risk registers.

The role bridges the gap between project delivery teams and senior management, providing the data and analysis needed for informed decision-making. On large programmes, the Project Controls Manager typically manages a team of planners, cost engineers, and risk analysts.

P6 Administrator

A P6 Administrator is responsible for the technical management and governance of the Primavera P6 environment, including user access controls, security profiles, OBS and EPS structures, calendars, activity codes, and system configuration. They ensure data integrity across the system, manage database maintenance, coordinate upgrades, and support end users with technical issues.

On multi-project or enterprise deployments, the P6 Administrator plays a critical role in maintaining consistency and standardisation across all projects in the portfolio.