Permit-to-work systems are designed to control individual work activities. They identify hazards, define controls, and authorise work to begin. What they do not do, on their own, is control how multiple activities interact. That is where simultaneous operations become critical.
SIMOPS refers to situations where two or more work activities take place in the same area or system at the same time. Each activity may be safe in isolation. The risk emerges when those activities interact.
Permit systems often appear robust when assessed one permit at a time. Coordination failures between permits are where risk is most likely to develop.
For a broader overview of how permit systems function, see The Permit-to-Work Guide: Managing High-Hazard Control of Work (2026).
Why SIMOPS Creates Risk
Most permit systems are built around single-job assessment. A permit defines the work scope, the hazards, and the controls required. This works when activities are isolated from each other.
In real operations, sites rarely run one job at a time. Maintenance, inspection, lifting operations, confined space entry, and electrical work often occur simultaneously within the same area. Risk does not stay inside one permit. It develops between them.
This is one of the recurring patterns examined in Common Permit-to-Work Failure Patterns Across Industries.
Where Coordination Breaks Down
SIMOPS failures rarely occur because permits are missing. They occur because coordination weakens under operational conditions. Several patterns repeat across sites.
Lack of visibility of active work
Supervisors cannot coordinate what they cannot see. When permit boards or digital systems do not accurately reflect live work, interactions between activities become invisible. This is often a failure of the visibility system rather than the permit itself, as examined in Permit Boards and Work Visibility: Why Coordination Often Breaks Down.
A structured coordination layer that tracks live work and identifies overlaps removes that visibility gap. The SIMOPS Operational Visibility Tracker provides that coordination layer in a practical operational format.
Assumptions between work teams
Work teams often operate within their own permit boundaries and assume that nearby work has been assessed and controlled. Without structured coordination, those assumptions replace verification.
Conflicting controls
Controls defined for one activity may introduce risk to another. Typical interactions include hot work near confined space entry, lifting operations over active work areas, electrical work affecting mechanical tasks, and isolation changes impacting adjacent work. Each permit may be correct individually. The conflict emerges between them.
Coordination under time pressure
SIMOPS risks increase during shutdowns, maintenance campaigns, and periods of high workload. Under these conditions communication compresses, permit issuing accelerates, and coordination becomes reactive rather than planned. This reflects how permit systems behave differently under pressure, as explored in Why PTW Systems Fail Under Pressure – And How Operational Drift Takes Hold.
The Role of Permit Systems in SIMOPS
Permit systems are expected to support coordination through permit boards or digital systems, issuing authority awareness, supervisor communication, and planning meetings or coordination reviews.
The effectiveness of these controls depends on whether they reflect real-time activity. If permit visibility is delayed, incomplete, or not trusted, coordination shifts to informal communication. That approach does not scale when multiple high-risk activities are running at the same time.
SIMOPS and Isolation Control
Coordination failures often extend into isolation management. Isolation changes made for one activity can affect another, particularly where isolations are removed while nearby work is ongoing, systems are shared and isolation boundaries are unclear, or teams make assumptions about system status.
These interactions are closely linked to isolation control weaknesses explored in Lockout Tagout and Permit-to-Work: Where Isolation Control Fails.
SIMOPS During Restart
Restart is one of the most critical phases for SIMOPS coordination. Multiple activities complete at different times, isolations are removed, and systems are progressively returned to service.
Without structured coordination, work may still be ongoing in adjacent areas, isolations may be removed too early, and communication gaps can emerge between teams. This phase is examined in more detail in Restart Is the Most Dangerous Phase of a Permit System.
Why SIMOPS Failures Are Often Missed
Traditional permit audits focus on individual permits. They check documentation, signatures, permit types, and compliance with procedures. These checks do not capture interactions between permits.
SIMOPS failures often leave no clear trace in documentation because each permit appears correct when reviewed in isolation. A more effective approach to examining coordination is outlined in How to Audit a Permit-to-Work System: The Operational Approach.
A Practical Way to Assess SIMOPS Risk
A useful question to ask is whether supervisors can clearly see, at any moment, what high-risk activities are happening across the site and how they interact. If the answer depends on verbal updates, individual awareness, or informal communication, then coordination risk is already present.
For a structured check of how permit systems behave under operational pressure, use the Permit System Pressure Test.
Structured Review
For organisation’s that want to examine how coordination functions under operational conditions, the Permit System Diagnostic Toolkit provides a structured set of questions covering visibility of work, interaction between permits, coordination during high workload, and communication between teams. The focus is on identifying where coordination may weaken before it results in an incident.
The Core Point
SIMOPS does not introduce new hazards. It exposes how existing hazards interact.
Permit systems are effective at controlling individual activities, but that effectiveness depends on how well those activities are coordinated. When coordination weakens, risk does not disappear. It shifts into the spaces between permits.
Key concepts are summarised in the Permit-to-Work Reference Guide.
Assessing Permit Systems in Practice
For organisations that want to assess how their permit-to-work system performs under real operational conditions, see Permit-to-Work System Review (Northshore Safety Services).