Bar Charts, Milestone Plans, and Precedence Logic

Introduction

Construction projects must transform design information, materials, labour, plant, finance, and approvals into a completed facility within agreed constraints. Planning identifies the work required and the resources needed; scheduling places that work in time and establishes logical relationships among activities. A schedule is therefore not merely a calendar. It is a model of how construction is expected to proceed.

This chapter examines three closely related scheduling tools. Bar charts communicate activities and durations on a time scale. Milestone plans identify significant events or control points without representing every operation. Precedence logic explains how activities are related, including finish-to-start, start-to-start, finish-to-finish, and start-to-finish relationships, together with lags and leads.

These tools remain important even when sophisticated project-management software is used. Software can calculate dates and display networks, but it cannot determine whether the underlying logic is physically realistic, contractually defensible, or sufficiently detailed. Professional scheduling requires judgement about construction methods, access, temporary works, safety, inspections, procurement, weather, and resource availability.

Learning Objectives

By the end of this chapter, a student should be able to:

1. Explain the purpose, structure, and limitations of bar charts and milestone plans.
2. Prepare a simple time-scaled bar chart from an activity list.
3. Distinguish activities, events, milestones, calendars, and schedule constraints.
4. Apply finish-to-start, start-to-start, finish-to-finish, and start-to-finish relationships.
5. Use lags and leads without replacing sound activity definition with arbitrary date offsets.
6. Recognise defective, excessive, circular, or misleading scheduling logic.
7. Interpret a construction schedule for planning, monitoring, communication, and control.

1. Scheduling as a Representation of Construction Work

A construction schedule represents a planned sequence of work. Each activity normally has a defined scope, a duration, a calendar, and relationships to other activities. The schedule may also include resources, cost, location, responsibility, and progress information.

Important distinctions are as follows:

• An activity is a measurable operation that consumes time and usually resources, such as installing reinforcement or testing a fire-alarm system.
• An event is a point in time with no duration, such as approval of a shop drawing.
• A milestone is a significant event used for control, reporting, payment, contractual administration, or decision-making.
• A calendar defines working days, working hours, holidays, shutdowns, and sometimes resource-specific availability.
• A constraint is a restriction on timing, such as a required completion date, a possession date, or an authority-imposed inspection window.
• A logic link expresses the dependency between two activities.

A schedule should answer at least five questions:

1. What work must be performed?
2. How long is each operation expected to take?
3. In what order can or must the work occur?
4. When are important decisions, approvals, and handovers required?
5. What actual progress or forecast change would affect completion?

The quality of a schedule depends on both its content and its logic. A visually attractive bar chart with weak logic may provide false confidence. Conversely, a logically sound network that is too detailed or poorly communicated may be difficult to use in the field.

2. Bar Charts

2.1 Definition and purpose

A bar chart, often called a Gantt chart, displays activities as horizontal bars against a time scale. The left end indicates planned start, the right end indicates planned finish, and bar length represents duration. Activities are commonly listed vertically in work-breakdown order.

Bar charts are effective because they communicate time directly. A site manager can quickly see which operations are planned in a particular week, while a client can identify major phases and forecast completion. They are particularly useful for:

• communicating the overall plan;
• preparing short-term and medium-term look-ahead schedules;
• comparing planned and actual progress;
• coordinating subcontractors and suppliers;
• presenting access, possession, and handover dates; and
• reporting progress to non-specialist stakeholders.

A basic bar chart may contain only activity names, dates, and bars. A more developed chart may include planned and actual bars, progress shading, logic arrows, milestones, a data date, a critical-path indication, and a legend.

2.2 Constructing a bar chart

A practical procedure is:

1. Define the scope and establish a suitable work breakdown structure.
2. List activities at a level of detail appropriate to the purpose of the schedule.
3. Estimate durations using quantities, productivity, crew composition, working hours, and calendar assumptions.
4. Identify logical predecessors and successors.
5. Determine planned start and finish dates.
6. Select a time scale, such as days for a short repetitive operation or weeks for a building project.
7. Draw or generate the bars and mark milestones.
8. Review constructability with the project team.
9. Record the approved baseline and update actual progress at defined reporting intervals.

For an activity with a start date and a duration, the finish date depends on the project calendar. In a simple continuous calendar, if duration is measured in elapsed days, the relationship may be written as:

where S is the start time, F is the finish time, and d is elapsed duration. If dates are measured as working days, the addition must be performed through the applicable work calendar rather than by simply adding calendar days. For example, a five-working-day activity starting on Monday may finish on Friday, whereas a five-calendar-day activity may finish on Saturday depending on the convention used.

The convention must be stated. Some organisations define an activity starting at the beginning of Day 1 and finishing at the end of Day 5; others use time points and calculate the finish at the start of Day 6. Both can be valid if applied consistently.

2.3 Worked example: preparing a simple bar chart

Consider the following illustrative fit-out sequence. Durations are working days and the project works Monday to Friday.

The bar chart would show A first, B and C overlapping after A, D after both services are sufficiently complete, and E followed by F. The dates reveal an important issue: if “close walls” requires both first-fix operations to be complete, its planned start should follow the later predecessor, B, not merely C. This illustrates why bars should be supported by logic review.

A text representation of the same plan is:

Activity                  1 Apr       8 Apr       15 Apr      22 Apr      29 Apr
Complete partitions       █████
First-fix electrical                  ████
First-fix plumbing                     ███
Close walls                                    ████
Prime and paint                                      █████
Final fixtures                                             ███

This display is useful for communication, but the underlying schedule should retain the exact dates, calendars, relationships, and assumptions.

2.4 Strengths and limitations

Bar charts are simple, intuitive, and effective for communicating timing. They can show overlap, phased work, planned versus actual performance, and near-term workload. However, they do not always show dependency logic clearly, especially when many activities overlap. A long bar may conceal several distinct operations, and a date may appear arbitrary if the predecessor reasoning is not visible.

A bar chart also does not automatically show the effect of delay. If an activity slips, the planner must understand its successors and available float. In a dense project, a network schedule or precedence diagram is more suitable for analysing these effects.

Common bar-chart defects include:

• bars with no defined activity scope;
• durations copied from a previous project without checking productivity;
• excessive use of summary bars as if they were executable activities;
• dates imposed without logic or resource analysis;
• no distinction between working and non-working days;
• failure to show approvals, procurement, testing, and handover; and
• updating the bar length without recording the actual cause of delay.

3. Milestone Plans

3.1 Meaning and function

A milestone plan is a schedule of significant zero-duration or event-based dates. Examples include:

• notice to proceed;
• completion of excavation;
• approval of structural drawings;
• arrival of a major item of plant;
• building watertight;
• energisation approval;
• substantial completion;
• practical completion; and
• client handover.

Milestones are useful because they focus attention on decisions and outcomes rather than on every daily operation. They can be used in contract documents, executive reports, payment plans, design-management schedules, procurement plans, and interface-management plans.

A milestone should have a clear definition and an identifiable evidence source. “Structure complete” is weak unless the project defines whether this means the last slab cast, all structural inspections passed, or a formal certification issued. A good milestone is observable, significant, and assigned to a responsible party.

3.2 Types of milestones

Milestones may be external, depending on a client, authority, utility, or supplier, or internal, controlled by the project team. External milestones require early identification of submission periods and response times. Treating an external approval as an instantaneous event is a common planning error.

3.3 Milestone plans and bar charts

A milestone plan does not replace a detailed schedule. It is a higher-level view derived from the detailed schedule. Each milestone should be traceable to the activities that produce it. If the milestone date changes, the planner should be able to identify the affected work and the reason for change.

A useful milestone register includes:

Milestones should not be used excessively. If every minor activity is labelled a milestone, the distinction between control points and ordinary work is lost. Conversely, a plan with only a final completion milestone may fail to identify emerging problems early enough.

4. Precedence Logic

4.1 Why logic matters

Precedence logic represents how one activity depends on another. It should reflect physical, technical, contractual, safety, access, information, and resource conditions. Logic is not simply a way to reproduce preferred dates. It is a statement about what must happen before, during, or after something else.

In the commonly used activity-on-node approach, each activity is a node and an arrow or relationship connects predecessor and successor activities. The four standard relationship types are finish-to-start, start-to-start, finish-to-finish, and start-to-finish.

4.2 Finish-to-start (FS)

In a finish-to-start relationship, the successor cannot start until the predecessor has finished, subject to any lag.

Here, S_B is the start of successor B, F_A is the finish of predecessor A, and L is the lag. With zero lag, this is written FS. A positive lag creates a waiting period; a negative lag is often called a lead.

Examples include:

• concrete placement FS curing period FS formwork striking;
• installation of a door frame FS hanging the door; and
• approval of a shop drawing FS fabrication.

FS is the most common relationship because many construction operations genuinely require completion of one condition before the next operation begins. However, it should not be used automatically where activities can overlap.

4.3 Start-to-start (SS)

In a start-to-start relationship, the successor cannot start until the predecessor has started, subject to lag.

Examples include:

• starting internal plastering after a preceding zone of masonry has started;
• starting excavation support installation after excavation has commenced; and
• beginning a repetitive installation crew after the preceding trade has established a workable area.

SS does not mean that the two activities finish together. The successor may continue after the predecessor finishes. A lag should represent a real condition, such as the time required to release the first work area, not an arbitrary attempt to make bars look attractive.

4.4 Finish-to-finish (FF)

In a finish-to-finish relationship, the successor cannot finish until the predecessor has finished, subject to lag.

Examples include:

• completion of testing and completion of commissioning documentation;
• completion of ceiling installation and completion of final above-ceiling inspection; and
• completion of a coordinated installation and completion of associated quality records.

FF does not require simultaneous starts. The successor may start earlier, provided its finish condition is not reached before the predecessor permits it.

4.5 Start-to-finish (SF)

In a start-to-finish relationship, the successor cannot finish until the predecessor has started, subject to lag.

SF is uncommon in ordinary building work but can be valid in shift handovers, temporary facilities, or operational changeover. For example, an outgoing security arrangement may not finish until the replacement security service has started. Because SF is easily misunderstood, it should be documented clearly and used only where the real dependency is from the start of one activity to the finish of another.

4.6 Relationship comparison

The inequalities express minimum conditions, not necessarily exact equality. If a successor starts later than the minimum allowed date because of resource limitations, access restrictions, or management choice, the relationship remains satisfied.

5. Lags, Leads, and the Quality of Logic

A lag is a deliberate time interval inserted between related activities. Positive lag may represent curing, statutory review, shipping, drying, or a required observation period. For example, if testing begins only two working days after installation finishes, the relationship is FS + 2 working days.

A lead is a negative offset that permits overlap. For instance, a predecessor may be scheduled FS − 2 days before the predecessor fully finishes. In construction, leads should be used cautiously because they can obscure the actual condition permitting the overlap. If the overlap is important and recurring, separate activities or an SS relationship may communicate the plan more clearly.

A lag is sound when it has:

• a physical, contractual, safety, or administrative basis;
• a defined duration and calendar;
• an identifiable owner or evidence source where appropriate; and
• a review method if conditions change.

A lag is defective when it is used to hide missing activities, force a target date, or compensate for weak logic. For example, “install finishes FS + 14 days complete” may be less informative than explicitly modelling inspection, correction, curing, and protection activities.

Worked example: evaluating relationships

Suppose Activity A, “pour slab,” finishes at the end of working Day 10. Activity B, “strip formwork,” requires three working days of curing. The sound relationship is:

If Activity C, “start blockwork in Zone 1,” can begin once the first part of the slab has gained adequate access and strength, it may be modelled as SS with a documented lag, provided the construction method supports that assumption. If blockwork can begin only after the entire slab is accepted, FS is more appropriate.

The correct relationship is determined by the physical method, not by which relationship produces the preferred completion date.

6. Forward and Backward Schedule Reasoning

A precedence network can be analysed by calculating earliest and latest dates. In a simplified activity-on-node network, the earliest finish of activity i is:

where ES_i is earliest start, EF_i is earliest finish, and d_i is duration, all expressed in consistent time units under a defined calendar.

For an FS relationship from i to j with lag L_ij:

For several predecessors, the earliest start must satisfy all conditions; therefore the controlling value is the maximum permitted predecessor value. For example, if B has two FS predecessors A and C:

This formula assumes a simple precedence network, consistent calendars, and no additional resource or constraint effects. Actual scheduling software may account for calendars, interruptions, imposed constraints, and relationship-specific calculations in more complex ways.

For a simple finish-based backward calculation, latest start is:

where LF_i is latest finish and LS_i is latest start. Total float is commonly defined as:

Float is the amount an activity can move without delaying the relevant project completion date, under the assumptions of the model. It is not automatically free time: a subcontractor, access window, contractual date, or resource demand may make some or all float practically unavailable.

Worked network example

Activity A, “excavate,” lasts 4 working days. Activities B and C follow A: B, “install drainage,” lasts 3 days, and C, “prepare subgrade,” lasts 5 days. Activity D, “place base course,” follows both B and C and lasts 2 days. Assume all relationships are FS with zero lag and a Monday start at Day 1.

• A: ES 1, EF 4.
• B: ES 5, EF 7.
• C: ES 5, EF 9.
• D must wait for both B and C, so ES is the larger of Day 8 after B or Day 10 after C under a start-of-day convention. Using elapsed-day notation, D starts after the later finish, C, and its duration is 2 working days.

The example demonstrates the controlling predecessor principle: B may finish earlier, but D cannot start until C also satisfies the required condition. The planner should not draw D after B alone merely because B is the more visible operation.

7. Sound, Excessive, and Defective Logic

7.1 Sound logic

Sound logic is complete enough to represent the work, reflects actual construction conditions, and remains understandable to those who use the schedule. It should connect major activities from project start to completion and include design, procurement, approvals, testing, commissioning, and handover where they affect time.

Good logic has the following characteristics:

• every major activity has a defensible predecessor and successor;
• relationships describe real dependencies;
• lags have stated reasons;
• activities are neither so broad that control is impossible nor so narrow that updating becomes burdensome;
• calendars reflect actual working arrangements;
• external approvals and information releases are visible;
• milestones are traceable to producing work; and
• the schedule can be updated using observable progress.

7.2 Excessive logic

Logic becomes excessive when it adds complexity without improving prediction, control, or understanding. Examples include linking every activity to numerous unrelated activities, inserting several overlapping constraints for the same condition, or using many artificial lags instead of defining real work.

Excessive logic can create:

• confusing critical paths;
• excessive sensitivity to minor date changes;
• difficult updates;
• hidden responsibility for approvals;
• apparent precision unsupported by field information; and
• numerous false delay impacts.

A schedule should be detailed enough to manage interfaces but not so detailed that the model becomes detached from the way work is executed.

7.3 Defective logic

Defective logic includes:

• open ends: activities with no predecessor or successor when one should exist;
• dangling activities: work not connected to a controlling completion milestone;
• circular logic: A depends on B while B depends on A, making the network impossible to calculate;
• unjustified constraints: dates imposed without modelling the actual cause;
• negative or unexplained lags: overlaps that cannot be defended physically;
• wrong relationship types: using FS when work can overlap, or using SS when completion is actually required;
• missing calendars: treating night work, weekends, shutdowns, or authority working hours incorrectly;
• duplicate logic: repeating the same dependency through several paths; and
• logic that bypasses activities: connecting a summary activity directly to a milestone while detailed work is not connected.

A schedule quality review should inspect both the graphical network and the activity data. A clean-looking bar chart cannot reveal every logic defect.

8. A Detailed Illustrative Case: Community Health Centre

Background

This fictional case concerns a two-storey community health centre with reinforced-concrete framing, masonry partitions, mechanical and electrical services, medical-gas installation, testing, and regulatory inspection. The project has a contractual completion milestone and a required health-authority inspection before occupation.

Problem

The contractor’s initial bar chart showed the project finishing on 30 September. It included broad bars for “internal works,” “services,” and “finishes,” but did not show design approvals, equipment procurement, commissioning, or authority inspection. Several activities were connected by arbitrary FS relationships, even though work could proceed by zone.

The client questioned whether the completion date was reliable. The project team needed a schedule that communicated the plan while also exposing the conditions controlling completion.

Analysis

The planning team divided the work by building zone and identified the following important dependencies:

• structural frame before masonry in each zone;
• masonry start before services rough-in in released areas;
• services rough-in before closing walls and ceilings;
• equipment delivery before final connection and commissioning;
• testing before regulatory inspection; and
• inspection approval before occupation.

The team also identified two long-lead items: the medical-gas plant and the main electrical switchboard. Their procurement activities were separated into submittal, approval, fabrication, delivery, installation, testing, and commissioning. This avoided hiding procurement risk inside a single “services” bar.

Approach and solution

The revised schedule used:

1. a detailed precedence schedule for analysis;
2. a milestone plan for client and authority reporting; and
3. a four-week look-ahead bar chart for site coordination.

In the detailed model, masonry in Zone 1 and Zone 2 could overlap after the frame reached defined release conditions. Services rough-in used SS relationships with masonry, each carrying a lag representing area release and safe access. Closing walls used FS relationships from the relevant rough-in inspections rather than from the broad start of services. Commissioning was linked to equipment installation completion and test records.

A milestone register included “building envelope complete,” “medical-gas plant delivered,” “all statutory tests passed,” “health-authority inspection,” and “occupation approval.” Each milestone had a definition and evidence requirement.

Outcome

The revised model forecast completion on 7 October, seven working days later than the original reported date. The apparent delay was not created by the revised schedule; it was revealed by previously omitted activities and realistic inspection durations. The team then negotiated earlier release of approved equipment information and resequenced external works to protect the inspection date. The forecast improved to 2 October, but the team retained a risk allowance for authority response time.

Learning points

• A summary bar can conceal several independent risks.
• Activity overlap is legitimate only when the work method supports it.
• Approvals, testing, and commissioning are real schedule activities, not administrative afterthoughts.
• Milestones are effective when their completion criteria are explicit.
• A revised forecast may initially move later because the model has become more honest and complete.
• The schedule should support decisions, not merely defend an optimistic date.

9. Schedule Updating and Professional Use

A baseline schedule records the approved plan. An update records actual starts, actual finishes, remaining duration, physical progress, revised logic where justified, and forecast dates. The update should preserve the history of change rather than overwrite it.

Progress should be measured using observable quantities or completion criteria. A percentage entered without a defined basis can produce misleading forecasts. For example, “80% complete” might mean 80% of labour hours, installed quantity, cost, or perceived effort; these are not necessarily equivalent.

A practical update cycle is:

1. establish the data date;
2. collect site records, inspection records, delivery information, and subcontractor updates;
3. verify actual progress independently where possible;
4. update remaining durations and forecast logic;
5. analyse changes to milestones and critical paths;
6. record causes, responsibilities, and mitigation actions; and
7. issue a controlled report with assumptions and limitations.

Scheduling information may have contractual and legal significance. Records should be accurate, contemporaneous, auditable, and protected from unauthorised alteration. A planner must not manipulate logic or progress to create a desired entitlement or conceal poor performance. If a date is uncertain, the uncertainty and its basis should be stated.

10. Digital Tools, BIM, and AI

Scheduling software can generate bar charts, calculate dates, filter activities, compare baselines, and identify open ends or circular relationships. Four-dimensional BIM can associate model components with activities to visualise construction sequence and access. These technologies improve communication when the underlying data is reliable.

AI-supported tools may classify activities, detect unusual durations, suggest relationships from historical projects, or identify likely conflicts between procurement and installation. Such suggestions require professional validation. AI may not understand a project’s contractual definitions, local authority practices, temporary works, safety controls, or site-specific access constraints. Responsibility for the schedule remains with qualified project personnel.

A useful governance principle is: automate calculation, not accountability. Software may calculate the consequence of a relationship, but the project team must justify the relationship itself.

11. Best-Practice Checklist

Before approving a bar chart or precedence schedule, ask:

• Is the scope complete and organised by a useful work breakdown structure?
• Are activities measurable and assigned to responsible parties?
• Are durations based on stated productivity and calendar assumptions?
• Are design, procurement, inspection, testing, and handover represented?
• Does each major relationship reflect a real condition?
• Are lags and leads explained and measured in the correct calendar?
• Are milestones defined by objective completion criteria?
• Are open ends, loops, duplicate links, and unnecessary constraints removed?
• Can progress be observed and updated consistently?
• Does the schedule represent the construction method, site access, safety, and resource plan?
• Can a delay be traced to its effect on successors and milestones?
• Are baseline, update, and change records controlled and auditable?

Chapter Summary

Bar charts display construction activities against time and are valuable for communication, coordination, progress reporting, and look-ahead planning. Their simplicity can also hide weak dependencies, unrealistic durations, omitted approvals, or unsupported completion dates.

Milestone plans focus on significant events such as approvals, deliveries, inspections, sectional completion, and handover. They provide a concise management view but must be traceable to detailed activities and supported by clear completion definitions.

Precedence logic expresses dependencies among activities. Finish-to-start links a successor start to a predecessor finish; start-to-start links starts; finish-to-finish links finishes; and start-to-finish links a successor finish to a predecessor start. Lags may represent curing, review, delivery, or other real waiting periods, while leads permit overlap and require particular caution.

Sound scheduling logic reflects construction reality, includes necessary interfaces, uses appropriate calendars, and remains understandable and updateable. Excessive logic creates complexity without useful control, while defective logic includes open ends, loops, unjustified constraints, wrong relationship types, and hidden work. Professional scheduling combines time-scaled communication with network reasoning, field evidence, ethical record keeping, and informed judgement.

Key Terms

Activity: A defined operation that consumes time and usually resources.

Bar chart: A time-scaled schedule showing activities as horizontal bars.

Baseline: The approved version of a schedule used for comparison with actual performance.

Calendar: The working-time rules applied to activities or resources.

Constraint: A restriction that limits when an activity or milestone may occur.

Duration: The amount of working or elapsed time assigned to an activity.

Event: A point in time with no duration.

Finish-to-finish (FF): A relationship in which a successor cannot finish before its predecessor finishes, subject to lag.

Finish-to-start (FS): A relationship in which a successor cannot start before its predecessor finishes, subject to lag.

Float: Allowable movement of an activity without delaying a defined completion date, under schedule assumptions.

Lag: A planned time interval inserted between related activities.

Lead: An overlap represented by a negative lag or equivalent relationship timing.

Milestone: A significant event used for control, reporting, approval, payment, or handover.

Precedence logic: The network of dependency relationships connecting activities.

Schedule update: A controlled revision recording actual progress and revised forecasts.

Start-to-finish (SF): A relationship in which a successor cannot finish before its predecessor starts, subject to lag.

Start-to-start (SS): A relationship in which a successor cannot start before its predecessor starts, subject to lag.

Total float: The difference between latest and earliest allowable timing for an activity under a defined completion condition.

Work breakdown structure: A hierarchical division of project scope into manageable work components.

Review Questions

Short Answer Questions

1. What information is communicated by the length and position of a bar in a bar chart?
2. Distinguish an activity from a milestone.
3. State the basic meaning of a finish-to-start relationship.
4. Give two legitimate reasons for using a positive lag.
5. Why should a milestone have an explicit completion definition?

Long Answer Questions

1. Explain the strengths and limitations of bar charts for construction planning and control.
2. Compare FS, SS, FF, and SF relationships and provide a construction example for each.
3. Describe a systematic procedure for preparing and approving a construction bar chart.
4. Explain how excessive or defective logic can produce misleading schedule forecasts.
5. Discuss how a detailed precedence schedule, a milestone plan, and a short-term look-ahead schedule can be used together.

Analytical / Application Questions

1. A ceiling installation can begin in each room two days after the first-fix services crew releases that room, but it cannot be completed until the services inspection for that room has passed. Recommend suitable relationships and explain your assumptions.
2. A contractor reports that a project will finish on the contractual date, but the schedule contains no activities for authority inspection, equipment commissioning, or correction of defects. Analyse the reliability of the forecast and propose corrective action.
3. In a network, Activity B has two finish-to-start predecessors: Activity A finishes on Day 12 and Activity C finishes on Day 15. Both relationships have zero lag. Explain the earliest possible start of B and identify what additional information is needed before declaring the date achievable.

Multiple Choice Questions with Answers

Question 1

Which scheduling tool displays activities as horizontal bars against a time scale?

A. Milestone plan

B. Bar chart

C. Resource histogram

D. Risk register

Correct Answer: B. Bar chart

Question 2

In a finish-to-start relationship, the successor activity may start when the predecessor has:

A. Started

B. Reached 50% progress

C. Finished, subject to any lag

D. Been assigned a resource

Correct Answer: C. Finished, subject to any lag

Question 3

Which relationship links the start of a successor to the start of its predecessor?

A. SS

B. FF

C. FS

D. SF

Correct Answer: A. SS

Question 4

A positive lag in an FS relationship most commonly represents:

A. An intentional waiting period

B. A circular dependency

C. A removed predecessor

D. A summary activity

Correct Answer: A. An intentional waiting period

Question 5

Which is the best example of a milestone?

A. Install 200 m² of blockwork

B. Carry out excavation for five days

C. Health-authority inspection passed

D. Operate a tower crane

Correct Answer: C. Health-authority inspection passed

Question 6

If Activity B has two zero-lag FS predecessors, A finishing on Day 12 and C finishing on Day 15, B cannot start before:

A. Day 12

B. Day 13

C. Day 15

D. Day 27

Correct Answer: C. Day 15

Question 7

Which condition is a defect in schedule logic?

A. A lag representing concrete curing

B. A milestone linked to its producing activities

C. A circular dependency between activities

D. An SS relationship for genuine overlapping work

Correct Answer: C. A circular dependency between activities

Question 8

The principal purpose of a milestone plan is to:

A. Represent every labour-hour expenditure

B. Highlight significant control and decision points

C. Replace all detailed activity logic

D. Calculate equipment depreciation

Correct Answer: B. Highlight significant control and decision points

Question 9

For an activity with earliest start ES_i and duration d_i, the simplified earliest-finish expression is:

A. EF_i = ES_i − d_i

B. EF_i = ES_i + d_i

C. EF_i = d_i − ES_i

D. EF_i = ES_i × d_i

Correct Answer: B. EF_i = ES_i + d_i

Question 10

Why should a lead or negative lag be used cautiously?

A. It always creates a non-working calendar

B. It may hide the physical condition that permits overlap

C. It converts an activity into a milestone

D. It eliminates the need for progress updates

Correct Answer: B. It may hide the physical condition that permits overlap