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 Permit-to-Work System Explained.
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.
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 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.
Most sites do not have a clear way to see all active permits across the area.
→ Use a structured Permit Coordination Board to track live work and identify overlaps.
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
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
periods of high workload
Under these conditions:
communication compresses
permit issuing accelerates
coordination becomes reactive rather than planned
This reflects how permit systems behave differently under pressure, as explored in Why Permit-to-Work Systems Fail Under Pressure.
The Role of Permit Systems in SIMOPS
Permit systems are expected to support coordination, typically through:
permit boards or digital systems
issuing authority awareness
supervisor communication
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
teams make assumptions about system status
These interactions are closely linked to isolation control weaknesses explored in Lockout Tagout (LOTO) and Permit-to-Work.
SIMOPS During Restart
Restart is one of the most critical phases for SIMOPS coordination.
Multiple activities complete at different times. Isolations are removed. Systems are progressively returned to service.
Without structured coordination:
work may still be ongoing in adjacent areas
isolations may be removed too early
communication gaps 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
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 Permit-to-Work System Audit Guide.
A Practical Way to Assess SIMOPS Risk
A useful question to ask:
Can supervisors 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
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 organisations 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
communication between teams
The focus is on identifying where coordination may weaken before it results in an incident.
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
If you want to assess how your permit-to-work system performs under real operational conditions, see Permit-to-Work System Review (Northshore Safety Services).