Key Points
- Multiple work activities occurring simultaneously in the same area or facility.
- Creates compound risks that may not exist when activities are performed separately.
- Requires dedicated coordination, often through a PTW coordinator or control room.
- Common during turnarounds, shutdowns, and large construction projects.
Definition
SIMOPS refers to multiple work activities taking place at the same time in the same area. These activities may interact and create additional risks. Proper coordination is essential to avoid conflicts.
Related Terms
Co-activity
Co-activity describes situations where different teams, contractors, or disciplines work in the same area at the same time, creating overlapping hazards that must be actively managed. In industrial environments such as refineries, power plants, and construction sites, co-activity is one of the most common sources of safety incidents because the actions of one team can directly affect the safety of another. For example, a welding team performing hot work near a team conducting gas-line maintenance creates a compounded risk scenario that neither team's individual risk assessment would fully address. Effective co-activity management requires shared situational awareness, joint toolbox talks, coordinated scheduling, and real-time visibility into all active permits in a given area. Digital permit-to-work systems play a crucial role by automatically flagging potential conflicts when multiple permits are issued for overlapping locations or timeframes. Unlike SIMOPS, which is a broader operational planning concept, co-activity focuses specifically on the human coordination challenge — ensuring that every team on site understands what other work is happening around them and what additional precautions are needed. Failure to manage co-activity has been identified as a contributing factor in numerous major industrial accidents, making it a key focus area for safety regulators and standards bodies worldwide.
Control of Work (CoW)
Control of Work is a broader operational framework that governs how work is planned, authorized, and executed safely across a site. It includes PTW processes, risk assessments, isolations, and coordination of simultaneous activities. CoW ensures that all work is visible, controlled, and aligned with site rules and safety requirements. In practice, it is the overarching system that connects different safety processes into one structured approach.
Permit Register
A permit register is a centralized record of all active, planned, and completed permits. It provides visibility into ongoing work and helps identify potential conflicts. In digital systems, it is often visualized as a dashboard or list. In practice, it is essential for operational awareness and coordination.
Dynamic Risk Assessment
Dynamic risk assessment refers to continuous evaluation of risks during the execution of work as conditions change. Unlike pre-planned assessments, it is performed in real time by workers on site. It is critical in environments where conditions evolve rapidly. In practice, it supports situational awareness and safe decision-making during execution.
More in Risk & Safety
Job Safety Analysis (JSA)
A Job Safety Analysis is a structured process used to break down a task into individual steps and identify hazards associated with each step. For every identified risk, appropriate control measures are defined to reduce or eliminate the hazard. JSA is typically prepared before work begins and is often linked directly to the permit. In practice, it ensures that work is systematically thought through rather than executed based on assumptions.
Point of Work Risk Assessment (PWRA)
PWRA is a risk assessment performed at the exact location where work will take place just before starting. It verifies that planned controls are still valid in the actual environment. It acts as a final validation between planning and execution.
Residual Risk
Residual risk is the level of risk that remains after all control measures have been implemented. It cannot be fully eliminated but must be reduced to an acceptable level. Understanding residual risk is critical for decision-making.
Last Minute Risk Assessment (LMRA)
LMRA is a final safety check performed immediately before starting work. It ensures that nothing has changed since the original assessment. It is often performed by the work team on site.
Frequently Asked Questions
How are SIMOPS managed in a digital PTW system?
Digital PTW systems provide real-time visibility of all active permits on a map or dashboard, allowing coordinators to detect overlapping work zones, conflicting isolations, or incompatible activities before they start.
Who is responsible for coordinating SIMOPS?
Typically the PTW coordinator or area authority is responsible for reviewing permit conflicts and ensuring simultaneous activities are compatible and safely managed.
Explore Our Guides
Deepen your knowledge with our comprehensive guides and expert resources.

Pirkka Paronen
CEO, Gate Apps
CEO of Gate Apps, expert in digital permit-to-work and HSEQ software.
