Introduction: Why ALARP Has Become a Critical Concept in Machine Safety
In modern manufacturing, safety leaders face constant pressure to reduce risk, prevent injuries, and stay compliant with OSHA, ANSI, and ISO standards, while balancing budgets, uptime, and ever-changing production demands. One concept that bridges these goals is ALARP, which stands for As Low As Reasonably Practicable.
ALARP is not new, but it is rapidly becoming one of the most important decision-making frameworks in safety engineering. It helps organizations determine how much risk must be reduced, how to prioritize improvements, and when the remaining risk level is acceptable for continued operation. Unlike vague phrases such as “safe enough,” ALARP provides a structured, defensible, and practical method for risk reduction.
For Safety Managers, EHS leaders, engineering teams, and plant managers, understanding ALARP is essential, not just for audits and compliance, but for building a culture that proactively reduces risk in a cost-effective, scalable way.
This guide breaks down what ALARP is, why it matters, and how to apply it specifically to machine safety and guarding in manufacturing environments.
What is ALARP? A Clear, Practical Definition
ALARP: As Low As Reasonably Practicable is a safety principle that states:
Risk must be reduced to the lowest level that is reasonably practicable, balancing the benefit of risk reduction against the cost, effort, and feasibility of additional controls.
It does not demand eliminating all risk (which is impossible), nor does it allow companies to ignore known hazards due to convenience or cost. Instead, ALARP requires doing everything that is achievable, unless the cost of additional risk reduction is grossly disproportionate to the safety benefit gained.
In simple terms, ALARP asks:
- Is there a real hazard?
- Is there a way to reduce it?
- Is the improvement practical?
- Would the cost or effort of further risk reduction be grossly disproportionate to the benefit?
- Is the residual risk now acceptable?
If the answers support moving forward, the risk can be considered ALARP.
Why ALARP Matters in Manufacturing and Machine Safety
1. OSHA Has No “Safe Enough” Clause
OSHA 1910.212 states that manufacturers must protect operators from machine hazards, but OSHA does not provide an exact risk threshold. ALARP provides the structured decision-making process needed to justify guarding decisions, corrective actions, and prioritization.
2. ALARP Supports ANSI B11 and ISO 12100 Risk Reduction
Both ANSI B11 standards and ISO 12100 (Safety of Machinery – General Principles for Risk Assessment and Risk Reduction) require risk to be:
- Identified
- Evaluated
- Reduced using engineering and administrative controls
- Demonstrated to be as low as reasonably practicable
ALARP provides the decision-making model behind that final step.
3. It Helps Safety Managers Prioritize What Comes First
Many facilities have dozens, or hundreds of legacy machines needing upgrades. ALARP helps justify:
- Which machines get guarding first
- What controls are “required” vs. “nice to have”
- Which improvements are most effective per dollar spent
This makes ALARP invaluable for yearly safety budgeting and 12-month improvement plans.
4. It Aligns Engineering, Maintenance, and Safety
ALARP helps overcome the common conflict:
- Safety wants compliance
- Engineering wants functionality
- Maintenance wants reliability
- Finance wants budget control
ALARP provides a path that satisfies all four groups.
The Core ALARP Model: The Three Risk Zones
ALARP uses a traffic-light-style risk model:
1. Unacceptable Region (High Risk – Red Zone)
Risks here must be reduced regardless of cost or effort. These are hazards with a high likelihood of severe injury or fatality.
Examples:
- Unguarded nip points
- Exposed rotating equipment
- Manual clearing of jams inside hazardous zones
- Defeatable interlocks
No discussion, the risk must be lowered.
2. Tolerable If ALARP Region (Yellow Zone)
Here resides most real-world hazards.
Risks are not immediately deadly, but they still must be reduced where practical.
Examples:
- The machine has guarding, but lacks stop-time measurements
- Light curtains are older and may not meet PLd/PLe
- Mechanical guarding exists but has gaps or bypass risks
Risk is accepted only if:
- All reasonable controls are in place
- Further reduction would be grossly disproportionate to the benefit
3. Broadly Acceptable Region (Green Zone)
Risk is already extremely low. No additional measures are required.
Examples:
- Fully guarded equipment with modern safety controls
- Automated processes requiring no operator interaction
- Verified PLd/PLe safety functions
Even still, documentation must prove the risk level.
How ALARP Applies to Machine Safety Guarding
Machine safety engineering uses three steps aligned with ALARP:
1. Identify the Hazard
Common machine hazards include:
- Shear points
- Crush points
- Pinch/nip points
- Entanglement hazards
- Ejection hazards
- Electrical hazards
- Stored energy hazards
This is often done through:
- A guarding assessment
- A TBRA (Task-Based Risk Assessment)
- An RRPP (Risk Reduction Prioritization Program)
2. Reduce Risk Using the Hierarchy of Controls
To achieve ALARP, controls must follow the risk reduction hierarchy:
- Elimination – Can the hazard be removed entirely?
- Substitution – Can the process be changed to a safer method?
- Engineering Controls – Machine guarding, presence sensing, automation
- Administrative Controls – Training, signage, safe work procedures
- PPE – Last line of defense
Engineering controls are the backbone of ALARP in machine safety.
3. Demonstrate That Risk is ALARP
This requires evidence:
- Before-and-after photos
- Risk scoring
- Stop-time measurement documentation
- Validation of safety devices
- Guarding drawings
- Cost-benefit justification
A machine is ALARP only when:
- Engineering controls have been applied
- Administrative controls are in place
- Residual risk is documented
- Further improvements would be grossly disproportionate
ALARP is not a “guess.” It is a documented decision.
Gross Disproportion: The Key ALARP Factor Manufacturers Must Understand
ALARP’s most misunderstood concept is gross disproportion.
It does not mean:
- “The company can’t afford it.”
- “We don’t have the downtime.”
- “It’s too inconvenient.”
Instead, gross disproportion asks:
Are the cost, downtime, engineering effort, and complexity so large compared to the amount of risk reduction that the improvement is no longer reasonable?
Examples where gross disproportion applies:
- Spending $250k on robotic cell redesign to reduce an already low risk by 1%
- Replacing a compliant PLd safety circuit with a more complex PLe system that provides marginal improvement
- Installing guards that would cripple production without meaningful benefit
Examples where gross disproportion does NOT apply:
- Adding guards to a shear hazard
- Installing interlocks on access doors
- Replacing broken or easily bypassed light curtains
- Completing stop-time verification
- Replacing missing point-of-operation guards
If a hazard could cause severe injury, cost is not a valid excuse.
ALARP vs. Compliance: Why They Are Not the Same
Many plants mistakenly believe that meeting OSHA or ANSI requirements means risk is low enough. ALARP goes beyond compliance.
Compliance asks:
- Does the machine meet the standard?
ALARP asks:
- Have we reduced risk as far as reasonably practicable?
- Can we demonstrate it?
A machine may be technically compliant yet still not ALARP if:
- Guarding is present but easily bypassed
- Stop-time distance is unknown
- The risk of reaching into the hazard still exists
- The safeguarding method is outdated
Conversely, a machine may be ALARP even if:
- It is getting older
- It cannot achieve perfect modern standards
- Further upgrades are grossly disproportionate
This nuanced distinction is why ALARP is so valuable for legacy machinery.
How Safety Managers Can Apply ALARP in a Real Manufacturing Plant
Here is a practical, proven roadmap for implementing ALARP in your facility:
Step 1: Conduct a Machine Guarding Assessment
This includes:
- Documentation of existing safety controls
- Photos of hazards
- Severity and likelihood scoring
- Identification of low-cost/high-impact improvements
This forms your baseline.
Step 2: Perform a Risk Evaluation (TBRA or RRPP)
This allows you to determine:
- Risk levels for each task
- Which hazards are unacceptable
- Which improvements reduce risk the most
- What belongs in the ALARP region
Step 3: Apply Engineering Controls
These often include:
- Barrier guarding
- Interlocked safety doors
- Light curtains and scanners
- Inxpect 3D radar
- Cable pull E-stops
- Emergency stop circuits
- Fixed T-slot guarding
- Zero-energy devices
- Fencing and perimeter guarding
Engineering controls provide the bulk of ALARP reduction.
Step 4: Document Residual Risk
This is critical for ALARP:
- What risk remains?
- Why is it tolerable?
- What controls were applied?
- Why are additional improvements not reasonably practicable?
This documentation protects the company in:
- OSHA inspections
- Insurance audits
- Corporate safety reviews
- Legal matters
Step 5: Build a 12-Month ALARP Safety Plan
This aligns risk reduction with:
- Budget cycles
- Planned downtime
- Maintenance schedules
- Capital projects
- New equipment purchases
This creates a structured improvement roadmap.
Common Misconceptions About ALARP in Machine Safety
No - “ALARP means we can leave some risk in place.”
Yes - Correct: Only residual risk that is extremely low and fully documented can remain.
No - “ALARP justifies doing less.”
Yes - Correct: ALARP requires doing everything reasonably possible.
No - “If we follow OSHA, we’re automatically ALARP.”
Yes - Correct: OSHA compliance is a minimum—not proof that risk is ALARP.
No - “ALARP is a loophole to avoid upgrades.”
Yes - Correct: ALARP removes loopholes by requiring documented justification.
ALARP and Legacy Machines: An Especially Important Connection
Older machines are frequent sources of:
- Missing guards
- Outdated controls
- Exposed hazards
- Bypass-able safety devices
- High-risk jam clearing
ALARP helps plant leaders avoid two extremes:
- Overpaying to retrofit a machine beyond reasonable benefit
- Underinvesting and leaving workers exposed
ALARP provides a defensible middle path, protecting employees while aligning with practical plant realities.
How ALARP Supports a Proactive Safety Culture
1. It shifts the mindset from reactive to proactive
Instead of waiting for an incident, near-miss, or OSHA complaint, ALARP encourages identifying and addressing hazards early.
2. It builds cross-functional accountability
Engineers, maintenance, production, and safety teams can agree on:
- Priorities
- Budgeting
- Improvement timelines
- Acceptable risk thresholds
3. It improves regulatory and insurance outcomes
Documenting ALARP:
- Reduces fines
- Strengthens audit outcomes
- Improves EMR and insurance rates
4. It increases employee trust
Workers trust companies that visibly invest in safety.
When ALARP is Not Acceptable: The Key Red Lines
ALARP cannot be used to justify ignoring hazards that present:
- High likelihood of injury
- Potential for amputation or fatality
- Known unsafe conditions
- Guards that are missing or defeated
- Nonfunctional safety devices
- Safety circuits bypassed or taped shut
If a control is inexpensive, quick, or simple to implement, it must be done, no exceptions.
ALARP is about balancing, not avoiding risk reduction.
Conclusion: ALARP Is the Future of Practical, Defensible Machine Safety
As manufacturing becomes more automated, more connected, and more regulated, ALARP provides a structured, defensible, and effective method to reduce risk. It is a bridge between engineering practicality and regulatory expectations and it empowers Safety Managers to bring clarity and confidence to machine safeguarding decisions.
By applying ALARP correctly, plants can:
- Reduce injuries
- Increase compliance
- Improve operational continuity
- Build a stronger safety culture
- Reduce downtime and long-term costs
- Create a clear, documented roadmap for risk reduction
ALARP is not a buzzword. It is a practical, proven framework that every modern manufacturer should be leveraging.
