Prevention through Design and Preconstruction Planning

Introduction and Context

Construction safety is often treated as an operational responsibility beginning when workers arrive on site. This view is incomplete. Many serious risks are created, intensified, or made difficult to control during feasibility studies, design development, procurement, temporary works planning, and construction sequencing. By the time work begins, opportunities to eliminate hazards may have been lost and only administrative controls or personal protective equipment may remain.

Prevention through Design (PtD), also called Design for Safety or Design for Construction Safety, is the systematic consideration of worker, public, user, and maintainer safety during the planning and design of a facility. Preconstruction planning converts those design intentions into executable arrangements involving methods, resources, logistics, temporary works, interfaces, emergency arrangements, and performance monitoring.

For postgraduate civil engineering professionals, the subject is not simply compliance. It involves risk-informed decision-making under uncertainty, multidisciplinary coordination, contractual governance, cost and schedule evaluation, and life-cycle thinking. A safe design must be technically feasible, buildable, maintainable, and compatible with the capabilities of the organizations that will deliver it.

Learning Objectives

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

1. Explain the principles and business case for Prevention through Design.

2. Integrate safety into feasibility studies, design reviews, constructability reviews, and procurement decisions.

3. Apply structured methods for hazard identification, risk assessment, and control selection.

4. Use BIM and digital coordination to identify spatial, sequencing, and interface risks.

5. Develop safety-oriented method statements, construction sequences, logistics plans, and temporary works strategies.

6. Evaluate safety implications in cost planning and life-cycle decisions.

7. Critically assess organizational, contractual, ethical, and regulatory barriers to design-stage safety management.

1. Foundations of Prevention through Design

1.1 The design–risk relationship

Design decisions determine geometry, access, material quantities, connection details, work at height, lifting requirements, excavation conditions, tolerances, temporary stability, and the number of interfaces between trades. For example, a façade designed with inaccessible anchor points may force workers to use improvised access systems. A deep basement with vertical sides and no allowance for safe temporary support may create an excavation hazard before the permanent structure exists. A heavy prefabricated component may reduce repetitive manual work but introduce lifting and transport risks.

PtD seeks to influence risk before exposure occurs. The preferred order of action follows the hierarchy of controls:

• Eliminate the hazard.
• Substitute a safer material, process, or arrangement.
• Apply engineering controls.
• Apply administrative controls, information, and training.
• Use personal protective equipment as the final layer rather than the primary strategy.

Design-stage elimination is usually more reliable than site-level behavioral control because it does not depend continuously on individual decisions. Nevertheless, PtD does not imply that every construction risk can be designed out. Construction involves changing conditions, incomplete information, weather, human behavior, subcontracting, and temporary states. The objective is to reduce inherent risk, make residual risks visible, and provide practical means of controlling them.

1.2 Risk, hazard, and exposure

A hazard is a source or situation with potential for harm. Risk is the combination of the likelihood of an unwanted event and the severity of its consequences. Exposure describes how, when, and for how long people interact with the hazard. A risk assessment should therefore ask three separate questions:

1. What can cause harm?

2. Who or what can be exposed, and under what conditions?

3. What credible outcomes could occur, and how effective are the proposed controls?

A common semi-quantitative representation is:

Risk score = Likelihood score × Consequence score

This expression is a prioritization device, not a physical law or a probability calculation. It is valid only when the scoring scales are clearly defined, applied consistently, and interpreted alongside the limitations of the assessment. Multiplying ordinal categories does not produce an exact probability of injury. High-consequence, low-frequency events must not be dismissed merely because their numerical score is moderate.

A more rigorous decision model may use expected loss:

Expected loss = Σ pᵢ Cᵢ

where pᵢ is the estimated probability of outcome i, and Cᵢ is its consequence expressed in a consistent unit, such as monetary loss or another decision metric. The model assumes that credible outcomes have been identified and that probability and consequence estimates are sufficiently reliable for the decision. In construction, uncertainty is often substantial; therefore, sensitivity analysis and expert judgment are essential.

2. Safety as a Feasibility and Design Criterion

2.1 Safety in feasibility studies

Feasibility studies should test more than financial return and technical viability. They should examine whether the project can be constructed safely within its environmental, social, regulatory, and logistical context. Early questions include:

• Can workers and emergency services access the site safely?
• Are there adjacent roads, railways, utilities, occupied buildings, waterways, or communities that constrain construction?
• What ground, groundwater, contamination, seismic, wind, flood, or climate hazards are present?
• Is the proposed project scale compatible with available lifting equipment, transport routes, labor skills, and temporary facilities?
• Can construction be completed without unacceptable public exposure?
• Will future inspection, cleaning, repair, replacement, and demolition be safe?

Alternative concepts should be compared using safety criteria alongside cost, time, performance, and environmental impact. A design that appears economical at tender stage may impose high temporary works costs, complex interfaces, or severe maintenance exposure later.

2.2 Safety in option selection

Options can be assessed through a multi-criteria decision matrix. Typical criteria include construction risk, maintenance risk, public interface, temporary works complexity, supply-chain reliability, carbon, cost, and schedule. Weighting must be agreed transparently because a weighted score can conceal value judgments. Decision-makers should also identify “deal-breaker” risks that cannot be traded away through scoring.

For example, a project team may compare cast-in-place and prefabricated structural systems. Prefabrication may reduce work at height and site congestion, but it requires reliable lifting studies, transport planning, connection tolerances, temporary stability, and adequate laydown areas. The correct decision depends on the whole system rather than on a general assumption that one method is always safer.

3. Hazard Identification Across the Project Life Cycle

3.1 Design hazard registers

A design hazard register records significant hazards, affected parties, control decisions, residual risks, responsible persons, and communication status. It should be a live management document, not a one-time form. Useful fields include:

• Hazard and initiating condition
• Construction activity or life-cycle stage
• People potentially exposed
• Existing design controls
• Additional required controls
• Assumptions and constraints
• Design owner and due date
• Verification status
• Residual risk and communication route

The register should distinguish hazards arising from the permanent works from those arising from temporary conditions. It should also identify interfaces, such as the transition from excavation support to permanent basement walls or from temporary access platforms to completed stairs.

3.2 Structured identification techniques

Several techniques are appropriate at different stages:

Checklists and prompts are efficient during concept design but may miss novel hazards.

What-if analysis asks questions such as “What if the crane cannot reach the planned pick?” or “What if the escape route is blocked during waterproofing?” It encourages practical challenge by experienced personnel.

Failure Mode and Effects Analysis (FMEA) examines possible failure modes, their effects, causes, and controls. It is useful for equipment, systems, and repetitive construction processes, but scores can become subjective.

Hazard and Operability Study (HAZOP) uses structured deviations from design intent. It is particularly useful for process plants and complex building services, though it can be resource-intensive for ordinary building projects.

Job Safety Analysis (JSA) or task risk assessment breaks a task into steps and identifies hazards and controls. It is strongest when used to develop a method statement, but it should not replace design-stage elimination.

Bow-tie analysis links causes to a top event and consequences, showing preventive and mitigative barriers. It is valuable for major accident hazards and barrier management.

3.3 Human factors and foreseeable misuse

A robust assessment considers fatigue, poor visibility, language differences, competence variation, production pressure, maintenance access, and foreseeable deviation from the intended method. Designs should not assume perfect compliance. However, accounting for foreseeable human behavior does not excuse inadequate training or supervision; it supports a more resilient system.

4. Constructability and Safety Reviews

Constructability is the extent to which a design facilitates efficient, safe, and quality construction by considering field conditions, available methods, sequencing, resources, and interfaces. A constructability review is not merely a cost-cutting exercise. It tests whether the design can be built without exposing people to unnecessary risk.

4.1 Review stages

Reviews should occur at concept, developed design, pre-tender, and preconstruction stages. The participants should include designers, construction planners, specialist subcontractors, temporary works engineers, safety professionals, operators, maintainers, and where appropriate representatives of affected workers.

A typical review examines:

• Access, egress, and emergency rescue
• Work at height and edge protection
• Lifting points, component weights, and lifting radii
• Temporary stability and support conditions
• Excavation support and groundwater control
• Plant routes, exclusion zones, and reversing movements
• Trade interfaces and simultaneous operations
• Material handling and ergonomic demands
• Fire, hot work, chemicals, and confined spaces
• Public protection and neighboring assets
• Inspection, testing, commissioning, maintenance, and eventual demolition

4.2 Design review questions

Reviewers should ask: “How will this be constructed?” rather than only “Does this meet the final design requirements?” Other useful questions are:

• What is the first unsafe or unstable temporary condition?
• What must be installed before this component can safely support another?
• Can workers reach the task without climbing, overreaching, or entering a fall zone?
• What happens if the planned crane, delivery route, or specialist subcontractor is unavailable?
• Which assumptions require verification before work begins?

Review outputs should be assigned to named owners with deadlines. An unclosed observation is not a control.

5. BIM Coordination and Digital Safety Planning

Building Information Modelling can support safety when it is used as a collaborative information environment rather than merely as a three-dimensional drawing tool.

5.1 Applications

BIM can assist with:

• Detecting physical clashes between structure, services, temporary works, and access systems
• Checking clearances for installation and maintenance
• Simulating crane zones, delivery routes, and laydown areas
• Visualizing sequence and temporary states using four-dimensional models
• Identifying high-risk interfaces between trades
• Recording hazard information against model objects
• Supporting handover information for maintenance and future alteration

Four-dimensional simulation can reveal that a permanent element blocks access before another element is installed, or that a tower crane’s planned operating zone conflicts with a public route. It can also show when exclusion zones overlap.

5.2 Limitations and governance

BIM does not automatically identify hazards. A model may be geometrically accurate but operationally unsafe. It may omit temporary works, equipment, work methods, or human behavior. Model users must therefore define information requirements, model ownership, revision control, and responsibility for safety decisions. Automated clash detection identifies geometric conflicts, not necessarily risks such as poor manual handling, inadequate competence, or an unsafe sequence.

Artificial intelligence can support image-based detection of missing edge protection, analysis of project records, and prioritization of recurring hazards. Such systems require validated training data, clear thresholds, privacy safeguards, and human verification. An AI alert should be treated as decision support, not as proof that a site is safe.

6. Method Selection, Sequencing, and Temporary Works

6.1 Method selection

Method selection should compare alternative means of achieving the required output. Relevant criteria include hazard elimination, worker exposure, temporary stability, plant interaction, weather sensitivity, quality, carbon, cost, schedule, and supply-chain resilience.

Off-site fabrication can reduce congestion and repetitive site work but may transfer risk to factories, transport, lifting, and connection operations. Mechanized excavation may reduce manual labor but increase plant-pedestrian interaction. A method is safer only when the complete chain of activities is considered.

6.2 Sequencing as a safety control

Sequence determines the conditions under which people work. A sound sequence should address:

1. Site establishment and access control.

2. Surveys, utility verification, and ground investigation.

3. Enabling works and temporary services.

4. Excavation support and groundwater management.

5. Foundations and temporary stability.

6. Structural erection and progressive stability.

7. Building envelope and internal works.

8. Testing, commissioning, occupancy, and demobilization.

The sequence should define hold points where work cannot proceed until a design, inspection, test, or authorization is complete. Examples include excavation support inspection, crane foundation approval, temporary stability verification, pressure testing, and energization controls.

6.3 Temporary works

Temporary works include scaffolds, formwork, falsework, propping, excavation support, haul roads, temporary bridges, lifting platforms, and access systems. They frequently carry significant loads while being exposed to changing geometry, weather, impact, and incomplete connections.

A temporary works system requires a clear design brief, competent design, independent checking proportionate to risk, controlled installation, inspection, modification control, and planned removal. “Temporary” does not mean low risk. In many projects, temporary works are the critical load-bearing system during construction.

7. Logistics, Interfaces, and Public Protection

A logistics plan translates the construction strategy into movement and separation arrangements. It should identify delivery windows, vehicle routes, pedestrian routes, hoists, cranes, storage capacities, waste removal, emergency access, welfare, fire points, and exclusion zones.

The plan must reflect actual site constraints and be updated as work fronts change. Poor logistics create congestion, manual handling, reversing, unauthorized access, and conflicting operations. The hierarchy for vehicle–pedestrian risk should prioritize physical separation, engineered controls, and controlled access rather than relying only on banksmen.

Interfaces require explicit ownership. Typical interfaces include client–designer, designer–contractor, principal contractor–subcontractor, permanent works–temporary works, construction–public road, and construction–occupied facility. Interface matrices can define who provides information, who verifies assumptions, who controls access, and who authorizes changes.

Public protection may require hoardings, covered walkways, traffic management, noise and vibration controls, protection from falling objects, environmental monitoring, and communication with neighbors. The public often has less knowledge of site hazards and must therefore be protected through robust physical and organizational controls.

8. Cost Planning and Life-Cycle Risk Decisions

Safety decisions have direct and indirect costs. Direct costs include temporary works, access systems, lifting aids, protection, supervision, inspections, and training. Indirect costs include delay, rework, disruption, insurance, reputational damage, compensation, investigation, and loss of future work.

Cost planning should include safety controls as normal project requirements, not as optional contingencies to be removed during value engineering. Value engineering should ask whether the same function can be achieved with lower total risk and life-cycle cost. Removing a permanent maintenance walkway may reduce capital cost while increasing future work-at-height exposure over decades.

Life-cycle safety extends from construction to operation, maintenance, refurbishment, adaptation, and demolition. Designers should provide safe access, isolation points, lifting provisions, fall protection, replacement routes, and information about hazardous materials. A design that is safe to construct but dangerous to maintain is not a fully successful design.

Where options have different timing and risk profiles, discounted cash-flow analysis may be used. The present value of a future cost can be represented as:

PV = F/(1+r)ⁿ

where PV is present value, F is the future cost, r is the discount rate per period, and n is the number of periods. The calculation assumes a chosen discount rate and a comparable monetary basis. It does not capture all safety values, such as dignity, pain, environmental harm, or catastrophic uncertainty. Therefore, economic appraisal must supplement—not replace—legal duties and ethical judgment.

9. Management, Contractual, and Regulatory Integration

Safety responsibilities should be established in project governance documents, scopes of service, design briefs, procurement requirements, and contracts. The client should define safety objectives and provide sufficient time and resources. Designers should identify and communicate design-related risks. Contractors should plan safe methods, verify site conditions, coordinate subcontractors, and control execution. These duties must be understood in accordance with the applicable national legislation and regulatory framework.

Contract language should avoid transferring responsibility without transferring authority, information, competence, and resources. A clause stating that a contractor is solely responsible for all safety cannot remove a designer’s duty to avoid foreseeable design hazards or a client’s duty to provide adequate project conditions.

Procurement evaluation should consider competence, proposed methods, temporary works capability, supervision, safety performance, workforce engagement, and realistic pricing. Selecting the lowest initial price while ignoring safety capability can create predictable risk and later cost.

Ethically, professionals must protect workers and the public even when commercial pressure encourages unsafe acceleration. Safety information should be communicated honestly, including uncertainty and unresolved assumptions. Near misses, design errors, and learning events should be reported without retaliation, while serious negligence must remain subject to accountability.

10. Applied Case: Illustrative Urban Basement Project

Background

An illustrative project involves a six-storey mixed-use building on a constrained urban site. It includes a two-level basement adjacent to a busy road and an occupied apartment building. The initial concept used open excavation with battered slopes and cast-in-place basement walls.

Problem

The site boundary did not provide sufficient space for safe batter slopes. The adjacent building had shallow foundations, groundwater was present, and deliveries would share a narrow public road. The initial program also required structural work to begin before the excavation support design was fully approved.

Analysis

The project team created a design hazard register and conducted a multidisciplinary constructability workshop. The principal hazards were ground movement, collapse, groundwater inflow, falling objects, vehicle–pedestrian conflict, crane oversailing, and work at height during basement construction. A four-dimensional BIM review showed that the proposed crane and delivery route would conflict with the temporary pedestrian diversion. A logistics study showed that simultaneous concrete deliveries and spoil removal would block emergency access.

The team rejected the open battered excavation because it required land outside the boundary and created unacceptable public and adjacent-building exposure. They compared a diaphragm wall, contiguous bored piles, and sheet piles, considering movement control, noise, vibration, waterproofing, cost, and available specialist capability.

Approach and solution

A contiguous piled wall with internal bracing was selected, subject to detailed geotechnical and temporary works design. The revised plan included:

• Early utility surveys and condition surveys of neighboring structures.
• Instrumentation for ground movement and groundwater levels.
• A temporary works design brief and independent check.
• A defined excavation sequence with inspection hold points.
• One-way delivery scheduling and physically separated pedestrian access.
• A revised crane position outside the public diversion zone.
• Prefabricated reinforcement cages with engineered lifting points.
• Edge protection integrated with the temporary works.
• Emergency rescue and flood response procedures.
• A BIM model including temporary bracing, access, exclusion zones, and delivery movements.

The contract program was adjusted to complete the temporary works design and verification before excavation. The cost increased because of bracing, monitoring, and logistics controls, but the design reduced reliance on unsupported excavation faces and uncontrolled public interaction.

Outcome

In this illustrative case, excavation proceeded without a collapse, significant movement, or public access incident. Monitoring identified a trend in groundwater rise, allowing pumping arrangements to be adjusted before excavation reached the affected level. The project experienced a modest increase in enabling-work cost but avoided potentially severe delay, third-party damage, and emergency stabilization.

Learning points

The case demonstrates that safety is shaped by land constraints, design choices, temporary works, logistics, procurement, and schedule governance. It also shows that monitoring is not a substitute for safe design; it is a verification and early-warning measure within a broader control system.

11. Challenges and Limitations

PtD faces several persistent challenges. Design teams may lack construction experience, contractors may be appointed too late, and safety information may be fragmented across disciplines. Commercial confidentiality can restrict early specialist input. Project schedules may reward design completion rather than design quality. Risk matrices may create false precision, and BIM may encourage confidence in visual models that omit temporary states.

Another difficulty is risk transfer. A design may shift a hazard from construction to maintenance, from one trade to another, or from the site to a supplier. Effective review follows the hazard through the full life cycle and across organizational boundaries.

Finally, safety performance cannot be inferred solely from low incident counts. A project with poor reporting may appear safer than one with an open learning culture. Leading indicators—such as closure of design actions, quality of temporary works inspections, participation in reviews, and verification of critical controls—should complement lagging indicators.

12. Best-Practice Framework

A mature prevention-through-design process should:

1. Establish safety objectives and life-cycle responsibilities at project initiation.

2. Gather reliable information about ground, utilities, neighbors, environment, and users.

3. Identify hazards before design freezes and maintain a live design risk register.

4. Prefer elimination and engineering controls over procedural dependence.

5. Involve constructors, temporary works specialists, maintainers, and workers early.

6. Review constructability, sequence, logistics, interfaces, and emergency response.

7. Model temporary conditions and access arrangements, not only the completed asset.

8. Integrate safety requirements into cost plans, procurement, and contracts.

9. Verify critical assumptions through surveys, calculations, inspections, and hold points.

10. Communicate residual risks clearly through drawings, specifications, models, and handover information.

11. Manage design changes through formal review and reauthorization.

12. Capture lessons learned and use them in future projects.

Chapter Summary

Prevention through Design places safety at the point where hazards can most effectively be eliminated or reduced: project definition, design, method selection, and planning. Feasibility studies should consider construction, public, operational, maintenance, and demolition risks. Constructability reviews test whether the proposed design can be built safely, while hazard registers maintain ownership of residual risks.

BIM supports spatial, sequencing, logistics, and interface analysis but requires competent interpretation and governance. Method selection must consider the entire chain of work, including prefabrication, transport, lifting, installation, temporary stability, and maintenance. Logistics planning separates people and vehicles, controls public exposure, and protects emergency access. Cost and life-cycle decisions should include safety consequences rather than treating safety controls as discretionary overheads.

Effective PtD is multidisciplinary, iterative, evidence-informed, and ethically grounded. It depends on early involvement, realistic programming, competent temporary works design, transparent communication, and verification of critical controls. Technology can strengthen the process, but responsibility remains with the professionals and organizations making and implementing decisions.

Key Terms

Prevention through Design: Designing out or reducing hazards before construction or use begins.

Design hazard register: A controlled record of identified hazards, controls, responsibilities, and residual risks.

Constructability: The extent to which a design facilitates safe, efficient, and practical construction.

Residual risk: Risk remaining after selected controls have been applied.

Hierarchy of controls: A ranked approach favoring elimination and engineering controls over administrative measures and PPE.

Temporary works: Structures or systems required to support construction but not forming part of the permanent facility.

Temporary stability: The ability of an incomplete or temporary system to resist expected loads and actions.

Method statement: A documented description of how work will be performed and controlled.

Hold point: A stage at which work must stop until specified verification or authorization is completed.

Constructability review: A structured multidisciplinary examination of how a design will be built.

BIM: A digital information-based representation of physical and functional project elements.

Four-dimensional BIM: BIM linked to time or construction sequence.

Interface risk: Risk arising where responsibilities, systems, trades, or project stages meet.

Life-cycle risk: Risk considered across construction, operation, maintenance, alteration, and demolition.

FMEA: Failure Mode and Effects Analysis, a structured method for examining failures, causes, and effects.

Bow-tie analysis: A barrier-based model linking causes, a top event, consequences, and controls.

Logistics plan: A plan for movement, storage, access, welfare, exclusion, and emergency arrangements.

Value engineering: Systematic improvement of required function and value, including safety and life-cycle performance.

Leading indicator: A proactive measure of control quality or risk-management activity.

Residual risk communication: Formal transmission of remaining hazards and required controls to affected parties.

Review Questions

Short Answer Questions

1. Define Prevention through Design and explain why it is more effective than relying only on site supervision.

2. Distinguish between a hazard, exposure, and risk.

3. What is the purpose of a design hazard register?

4. Identify four matters that should be examined in a constructability review.

5. State two limitations of using BIM for construction safety.

Long Answer Questions

1. Explain how safety should be incorporated into feasibility studies and option selection.

2. Discuss the hierarchy of controls and its application to design-stage decision-making.

3. Explain how construction sequencing and temporary works influence safety risk.

4. Analyze the role of procurement, contracts, and organizational governance in PtD.

5. Discuss how life-cycle cost and maintenance considerations can alter a design safety decision.

Analytical / Application Questions

1. A proposed basement excavation is adjacent to an occupied building and a public road. Develop a structured process for identifying, assessing, controlling, and monitoring the major risks.

2. Compare a prefabricated structural system with a cast-in-place system using safety, logistics, temporary works, cost, and life-cycle criteria. State the additional information required before selecting an option.

3. A BIM clash-detection report identifies no geometric conflicts, but the planned sequence requires workers to install services above an unprotected edge. Explain why the model has not demonstrated safety and propose corrective actions.

Multiple Choice Questions with Answers

Question 1

Which control is generally preferred first under the hierarchy of controls?

A. Personal protective equipment

B. Worker training

C. Hazard elimination

D. Warning signage

Correct Answer: C. Hazard elimination

Question 2

What is the primary purpose of a design hazard register?

A. To record only accidents after construction begins

B. To track hazards, controls, responsibilities, and residual risks

C. To replace all method statements

D. To calculate the contractor’s profit

Correct Answer: B. To track hazards, controls, responsibilities, and residual risks

Question 3

A risk score calculated as likelihood multiplied by consequence should be understood as:

A. An exact probability of injury

B. A prioritization tool based on defined scoring scales

C. A legally universal measure

D. A substitute for engineering judgment

Correct Answer: B. A prioritization tool based on defined scoring scales

Question 4

Which BIM application most directly supports analysis of construction sequence?

A. Two-dimensional plotting only

B. Four-dimensional simulation

C. Font standardization

D. Document compression

Correct Answer: B. Four-dimensional simulation

Question 5

Why are temporary works especially important in construction safety?

A. They are always cheaper than permanent works

B. They often support loads during incomplete and changing conditions

C. They require no independent checking

D. They are excluded from design responsibility

Correct Answer: B. They often support loads during incomplete and changing conditions

Question 6

Which item is an example of a hold point?

A. Allowing excavation to continue without inspection

B. Stopping work until excavation support is verified

C. Removing all monitoring requirements

D. Starting a new trade without coordination

Correct Answer: B. Stopping work until excavation support is verified

Question 7

What is a major limitation of automated BIM clash detection?

A. It cannot identify any geometric conflict

B. It identifies geometry but may not identify human, sequence, or behavioral risks

C. It prevents all design changes

D. It replaces temporary works design

Correct Answer: B. It identifies geometry but may not identify human, sequence, or behavioral risks

Question 8

In life-cycle safety planning, designers should consider:

A. Construction only

B. Only the lowest initial capital cost

C. Operation, maintenance, alteration, and demolition as well as construction

D. Only the contractor’s insurance premium

Correct Answer: C. Operation, maintenance, alteration, and demolition as well as construction

Question 9

Which arrangement best reduces vehicle–pedestrian interaction?

A. Relying solely on verbal warnings

B. Physical separation and controlled access

C. Increasing vehicle speed

D. Removing pedestrian routes

Correct Answer: B. Physical separation and controlled access

Question 10

A future cost of 121,000 monetary units occurs two years from now at a discount rate of 10% per year. Its present value is:

A. 100,000

B. 110,000

C. 121,000

D. 133,100

Correct Answer: A. 100,000