For decades, the construction industry has lagged behind other sectors in productivity and efficiency. Traditional construction methods, dependent on on-site labor and weather conditions, often result in delays, cost overruns, and inconsistent quality. Modular construction is a promising solution aiming to transform this sluggish sector into a more streamlined, tech-enabled industry.

By moving much of the building activity from unpredictable construction sites into controlled, factory-like environments, prefabricated (or “prefab”) construction is creating opportunities for faster, cleaner, and more efficient building processes. However, despite its advantages, modular construction introduces a new set of safety challenges that must not be overlooked. In this article, we’ll explore the benefits of prefabricated construction, while highlighting the critical need for specialized hazard identification and risk assessment (HIRA) to address the unique safety risks in both off-site and on-site operations.

What is Prefabricated or Modular Construction?

Prefab or modular construction involves off-site manufacturing of standardized building components, which are later transported and assembled at the final construction site. We can think of it, like assembling a complex set of Lego blocks: walls, floors, ceilings, and even entire rooms are created in a factory setting, then delivered and stacked into place.

Unlike the traditional approach, where raw materials are brought to the job site and assembled piece by piece, modular construction moves much of the heavy lifting to an off-site environment. This shift enables greater control over quality, faster turnaround times, and reduced dependency on weather or site-based logistics.

Take the example of Marriott International, which embraced modular construction to build several of its hotels across North America. By manufacturing entire rooms off-site, including plumbing, fixtures, and furniture, and then assembling them on location, Marriott has reported a reduction in construction time by up to 25%. In another instance, Singapore’s Housing and Development Board (HDB) used modular methods to deliver public housing projects significantly faster while ensuring consistent quality and lower labor dependency.

Why Modular Construction is Gaining Ground

The rise in prefab adoption is not accidental. Modular construction offers a series of compelling benefits:

• Faster project completion times: Project timelines have shown acceleration by 20% to 50% in many recent modular builds. This is extremely beneficial for time-sensitive projects like hospitals, schools, or hotels.

Image source: https://www.mckinsey.com/capabilities/operations/our-insights/modular-construction-from-projects-to-products

• Improved cost efficiency: Modular construction can cut costs by more than 20% in some projects, particularly when combined with efficient supply chain management and bulk material procurement.

Image source: https://www.mckinsey.com/capabilities/operations/our-insights/modular-construction-from-projects-to-products

• Reduced environmental impact: With materials cut to exact specifications and leftovers recycled in controlled environments, modular factories produce less waste and lower carbon emissions compared to traditional sites.

• Minimized weather delays: Since much of the fabrication occurs indoors, rain, wind, and temperature extremes have minimal impact on project timelines, a major advantage in unpredictable climates.

• Better quality control: Controlled factory settings allow for standardized processes and thorough inspections, reducing on-site rework and ensuring consistent build quality.

These benefits are translating into significant market momentum. The global modular construction market is projected to grow from USD 104.1 billion in 2024 to USD 140.8 billion by 2029, at a CAGR of 6.2%. With increased penetration, the market value in Europe and the United States alone could reach $130 billion by 2030. Yet, amidst this rapid growth and optimism, a sobering reality is often ignored.

 Statistics and image source: Modular Construction Market

The Safety Risks Associated with Prefab Construction

While modular construction is often praised for its efficiency and quality control, it introduces a unique set of safety risks that cannot be ignored. The division of work between off-site manufacturing, transportation, and on-site assembly adds layers of complexity that traditional construction rarely encounters. Unfortunately, despite its reputation for being safer, evidence shows a troubling pattern of accidents and fatalities in the prefab sector.

A growing body of data reveals that many of these risks emerge not on the jobsite, but during the supposedly safer off-site production phase. A 2024 study revealed that a staggering 70% of fatalities occurred during off-site production. This indicates deep-rooted systemic vulnerabilities in the prefab process, especially during fabrication. Additionally, OSHA records over two decades have linked many injuries to poor handling of heavy components, especially during cutting, lifting, and equipment operation inside modular manufacturing facilities.

Manufacturing Hazards: Hidden Dangers in Controlled Environments

Factory settings are typically viewed as safer due to climate control, automation, and standard procedures. However, in prefab construction, the manufacturing phase often involves high-risk tasks, including the use of heavy-duty cutting tools, cranes, and machinery for shaping steel frames, concrete panels, and utility lines. Workers frequently operate in tight quarters with large, unwieldy components, where one small misstep can result in crushing injuries or severe lacerations.

Many of the incidents reported involve workers being struck by falling modules, accidents involving overhead cranes, or injuries caused by rotating machinery and saws. The pace of production in modular factories is also a contributing factor. With productivity targets high and timelines compressed, the risk of human error, overlooked maintenance, or skipped safety protocols increases significantly.

Transportation Risks: Safety on the Move

Once modules leave the factory, they are typically transported via trucks or trailers, often over long distances. While transportation may seem like a logistical task, it poses serious structural and safety risks. Modules are large, heavy, and often top-heavy, making them vulnerable to shifting, tilting, or detachment during transit if not properly secured.

Common risks during transportation include:

• Mechanical failure of restraints or trailers
• Shifting of modules during sudden stops or turns
• Load imbalance leading to tip-over events
• Accidental contact with low-hanging power lines or overpasses

In poorly coordinated setups, even the loading and unloading process can cause accidents if lifting equipment is misused or structural checks are skipped. Without clear communication between factory teams, transport operators, and on-site crews, misalignment in safety expectations can lead to serious consequences before installation even begins.

Assembly and Installation: A Critical Danger Zone

Once the modules are transported to the construction site, the installation phase introduces a different set of dangers, often more complex than traditional building practices.
 
1. Fall Hazards from Elevated Heights
Workers often operate at elevations of 20 to 60 feet or more during module installation. Platforms, scaffolds, or suspended access systems are used to guide module placement, bolt or weld interconnections, install rooftop systems such as HVAC or solar panels

Without proper anchorage points, personal fall arrest systems (PFAS), and guardrails, the likelihood of severe falls increases dramatically, especially in windy conditions or when working under pressure.

2. Crushing Accidents from Swinging or Dropped Modules
Each prefab module is hoisted into place using tower cranes or hydraulic mobile cranes, often with custom rigging systems. Even with tag lines and lift plans, modules can:

• Swing uncontrollably in crosswinds due to their large surface area
• Drop if lifting lugs fail or if the rigging is improperly configured
• Cause pinch-point injuries when workers attempt to manually guide them into alignment

These situations can result in multi-ton crushing incidents, which are almost always fatal or permanently disabling.

3. Structural Collapse from Misalignment or Inadequate Connections
Proper module installation demands millimeter-level alignment to ensure that:

• Load paths are accurately transferred from one module to the next
• Seismic and wind load tolerances are maintained as per structural design codes
• Lateral bracing, post-tensioning cables, or intermodular fasteners are correctly engaged

Even a minor misalignment in horizontal or vertical tolerances (often no more than 5-10 mm) can lead to uneven load distribution, compromise structural integrity, and result in progressive collapse, particularly in multi-story buildings.

4. Mechanical Failures in Lifting Equipment
Lifting equipment used in modular construction faces unusually high demand, far beyond those encountered in traditional building projects. Cranes are often required to function at or near their maximum rated load capacities, especially when hoisting large, fully assembled modules. To handle these intense loads safely, rigging gear such as slings, shackles, and spreader bars must be meticulously maintained and rated for dynamic loads.

5. Electrical and Utility Hazards During Fit-Up
Once installed, modules must be connected for utilities like electrical, plumbing, and HVAC. Unlike conventional builds, modular MEP systems have much tighter tolerances, leaving little room for error. Misaligned conduits or poor connections can lead to arcing, leaks, or pressure failures. Workers also face confined space hazards and potential live wire exposure, especially if proper lockout/tagout procedures are not followed.

Why Safety Needs a Rethink in Modular Construction

The assumption that modular is always safer than traditional methods need to be challenged. Here’s why prefab construction requires a complete safety overhaul:

1. Fragmented Oversight
In traditional construction, continuous on-site oversight is enforced by established safety officers and regulatory frameworks. Modular construction, however, splits responsibility between off-site factories and on-site assembly, often leading to blurred lines of accountability. This fragmentation can result in missed inspections, overlooked defects, and inconsistent application of safety standards between the factory and the site.

Many regulatory bodies and safety standards were designed for conventional construction sites and do not address the unique split-site workflow of modular projects.

2. Underrated Manufacturing Risks
Factory environments are assumed to be safer, but they pose their own set of risks-heavy machinery, repetitive tasks, sharp tools, and the handling of large structural modules. These hazards require rigorous, factory-specific safety standards, which are often lacking or inconsistently enforced.

3. Lack of Standardization
The modular construction industry lacks unified global safety standards. While some countries require compliance with broad codes like the International Building Code (IBC) or national building codes, there is no universal modular-specific safety standard. This leads to inconsistent practices between manufacturers, variable worker training, and uneven compliance with regulations such as OSHA or local safety laws.

4. Limited Safety Data and Regulation
Most safety regulations are built for conventional job sites, not modular workflows. In many regions, especially developing countries, regulatory frameworks are still catching up to the rapid adoption of prefab methods. The lack of modular-specific safety laws and incident tracking systems means that risks may go unreported or unaddressed, hampering efforts to proactively mitigate hazards.

Where Do We Go from Here? A Hazard Identification and Risk Assessment Approach

Modular construction offers speed and scalability, but only if its unique risk factors are addressed systematically. Here’s how we can advance safely and intelligently:

1.) Develop Modular-Specific HIRA Protocols
Most traditional construction HIRA frameworks are not designed to capture the complexity of modular workflows. Prefab environments introduce distinct hazards, like the risks associated with heavy module lifting, high-precision alignment, confined internal spaces, and compressed project timelines. These are often overlooked in conventional site-based assessments.

A more relevant approach involves tailoring risk identification tools specifically for off-site fabrication, inter-module load transfer, and transport vulnerabilities. These refined protocols should also factor in dynamic risks like vibration during transport or shifting during crane lifts. Without a prefab-focused lens, critical hazards may go unnoticed until failure occurs.

2.) Implement Dual-Phase Safety Audits
Modular projects operate in two distinctly hazardous zones: the factory floor and the construction site. The risk landscape at each phase is unique and demands its own audit. During off-site manufacturing, the key risks involve mechanical handling equipment, repetitive strain injuries, and material handling hazards.

On the other hand, on-site installation introduces dangers such as working at heights, high-tension rigging operations, structural misalignment, and crane-related incidents. Conducting separate audits for these two phases ensures that controls are matched to the real-time environment and risk intensity, rather than relying on a one-size-fits-all safety assessment.

3.) Invest in Specialized, Role-Specific Training
Prefab construction requires a hybrid skill set, part factory technician, part site installer. Workers involved in module lifting, alignment, or electrical and plumbing integration must be trained for the precision and pace that prefab demands.

Unlike traditional construction, where work is sequential and often segmented, modular builds involve parallel workflows and compressed timelines. Therefore, training must include rigging certifications, tolerance measurement, module fit-up best practices, and hazard-specific simulations. A push toward standardized certification programs for “modular installation specialists” can raise the overall competence and safety resilience of the workforce.

4.) Create a Unified Safety Responsibility Framework
One of the biggest safety blind spots in modular construction is the fragmentation of accountability. Manufacturers, transport companies, and site contractors often operate in silos, leading to gaps in communication and safety oversight. Establishing a unified safety responsibility matrix helps ensure that every phase of the modular lifecycle is covered, from production to transport, to installation and post-assembly inspections.

Creating a shared digital risk register can also help all parties track issues, assign mitigation tasks, and log incident trends, reducing the likelihood of duplicated effort or ignored warnings.

5.) Leverage Technology for Real-Time Risk Mitigation
Technology plays a critical role in bridging the gaps between safety planning and on-ground execution. IoT-enabled sensors embedded in modules can monitor vibrations, structural integrity, and stress during both transportation and installation. Likewise, AI-powered visual inspection tools can help detect flaws like weld inconsistencies or minor misalignments before they escalate into safety incidents.

Real-time data collection enables project managers to respond immediately to safety deviations, rather than relying on post-incident investigations. Integrating this data into a centralized safety dashboard helps ensure proactive risk mitigation becomes a built-in part of the process, not just a box to check.

Also Read – Key Elements of a Robust Construction Safety Plan

Partner with Chola MS Risk Services for Safer Modular Construction

As the sector grows, so do the hazards, from factory-floor accidents to complex on-site installation dangers. Without robust hazard identification and risk assessment (HIRA) tailored specifically for prefab workflows, the promise of modular construction could be overshadowed by preventable incidents and costly setbacks.

Chola MS Risk Services specializes in comprehensive hazard identification and risk assessment solutions designed for the complexities of modular construction. Our expertise bridges the gap between factory and field, offering:

• Modular-specific HIRA protocols that address off-site fabrication, heavy module lifting, and precision alignment risks.
• Dual-phase safety audits to ensure both manufacturing and installation phases are thoroughly assessed and protected.
• Specialized training programs to equip your workforce with the skills needed for safe, high-precision modular assembly.
• Unified safety frameworks that eliminate gaps in accountability across all stakeholders.
• Advanced technology integration for real-time risk monitoring and proactive safety management.

Don’t let hidden dangers undermine your project’s success. Choose Chola MS Risk Services to safeguard your people, protect your investment, and set a new standard for safety in modular construction.

Contact us today to schedule a modular construction risk assessment-and build with confidence.