Simultaneous operations: assess overlapping tasks, times and work areas
30-second summary
Two tasks that appear acceptable on their own can create hazards where they meet. Reviewing simultaneous operations is more than collecting separate risk lists. Identify how sparks, loads, gases or energy can reach another crew, then decide whether timing or space must be separated. Communicate the revised sequence to every affected team.
- Zone boundary: identify overlap between work areas and material routes.
- Stored materials: assess effects on route width and visibility.
- Intersection: coordinate access where people and materials meet.
- Alternative route: check that diversion avoids other work zones.
Field practitioner note
Hazards that travel beyond a task boundary
Tasks can overlap in effect even when their points on a map are separate. Sparks travel downwards, a load travels between pick-up and landing, and released gas does not stop at a tape boundary. Consider affected levels and directions, not only points on a plan.
Shared equipment creates less visible interfaces. A supply used for one team's test may energise another team's machinery, or material may enter through common pipework. Separate permits do not make the tasks independent. Identify shared isolation, power, ventilation and access before fixing the sequence.
“Finished” may also be insufficient. After painters leave, neighbouring hot work still depends on the material and ventilation condition. A paused lift does not make the suspended-load area a passage. A timetable that omits the condition ending a hazard gives a finish time without establishing readiness for the next task.
Coordination is therefore not filling every slot. It identifies what can happen when tasks meet and breaks the hazardous combination through time separation, physical separation or a changed method. Adding supervision alone does not make incompatible tasks suitable to run together.
Example: lifting and deliveries share a passage
This is a coordination example. If a lift to an upper level and another team's delivery need the same passage, telling the driver a lifting time is not enough. Late arrival or a delayed lift can recreate the overlap. Agree the actual condition for reopening the route.
With time separation, hand over passage after the lifting team verifies a stable load and the end of associated equipment movement. Tell the delivery team where to wait and when access is released. Check that waiting vehicles do not obstruct escape or other work. If there is no safe waiting area, the delivery schedule itself may need to change.
With a diversion, check usability for the actual vehicles and pedestrian movement. A line on a map is not a functioning route. Examine whether it rejoins the lifting area or passes below an overhead load route. Check the entire route so a driver does not have to cross another work boundary to turn back.
Success is not “coordination meeting held”. It is separation of the tasks under agreed conditions understood by workers. When timing changes, revise the decision for both teams so neither enters on the basis of the old schedule. Connect changes affecting work plans to their approval process.
The same scheduling arrangement alone does not resolve a shared power test and maintenance task. Identify whether they share an energy boundary, then determine personnel clearance and the required isolation transition. Spatial separation leaves the transfer path intact if the supply is common. Select the method around shared energy and equipment, not merely job names.
Make unresolved decisions explicit. “Discuss on site” may leave conflicting decisions at the start. Identify what must be checked, the role authorised to decide and the task held pending that decision.
Figure 2 highlights the checks described here.
- Lifting path: identify load movement to locate overlap with nearby work.
- Delivery route: compare movement timing and route with the lift plan.
- Intersection: coordinate sequencing and access where activities meet.
- Alternative route: check that a diversion does not intrude on other work.
Preparation: identify interfaces rather than just team names
Use schedule locations and times, but compare more than a flat plan. Distinguish work above and below, inside and outside equipment, and tasks using the same passage. Add equipment and possible material, spark, noise or energy changes where a short job name hides its effects. Include the teams needed to match the plan to actual locations.
Pair interacting tasks and describe the transfer path. For lifting and deliveries, locate the crossing of the load route and vehicle route. For hot work near open maintenance, consider possible flammable releases relative to ignition sources. “Beware of simultaneous work” does not establish what must be separated.
Record dependencies involving common isolation or access. Establish what must finish before testing or energisation and whose escape would be affected by loss of a temporary route. Identify who checks the condition, not only the finish time. Changes to a shared element cannot be approved solely for one team's convenience.
Figure 3 highlights the checks described here.
Coordination: separation and release conditions
For time separation, define how the preceding task is released. Consider passage reopening after the load has landed securely and associated movement has stopped. Separating ignition sources and flammable materials requires residual-hazard, measurement and ventilation conditions, not a clock time alone. Use the relevant procedure for equipment and substance-specific criteria.
For spatial separation, check whether the boundary can interrupt the hazard path. A notice alone cannot block sparks or falling objects. Assess the position and performance of physical protection and its effects on escape and other access. If the barrier removes visibility, reconsider signalling and observation.
Give both affected teams the same revised information. Coordination has not reached the field if one team understands the new morning slot while another follows the old afternoon plan. Agree the change, readiness condition and mutual confirmation points before work. Updating an electronic timetable is different from workers knowing the new conditions.
When urgent work is added, examine the new interfaces first. Use the equipment movement, pipe opening or power change to assess affected areas rather than copying an old assessment. Do not begin the changed task before deciding whether neighbouring work may safely continue.
Completion: the condition passed to the next team
The finishing crew should distinguish departure from the hazards left behind. Temporary cables, materials or openings may affect the next task. Do not use one completion label for housekeeping and approval to restore shared equipment. Remove restrictions from the coordination record after checking that the effect has ended.
Delayed work may overlap with the following day's new work. Carry it into the next shift and plan rather than leaving it only on today's table. Retained isolations and restricted areas are important handover information. Record their objects and boundaries so the next crew can locate and verify them.
Checks for interacting tasks
The table asks coordination questions for task combinations. Determine the actual affected area and release conditions through the site assessment. Do not apply one exclusion distance or waiting period to every combination.
| Stage | Object | Condition |
|---|---|---|
| Shared route | Lifting and delivery vehicles | Check release after landing and rigging clearance |
| Different elevations | Work above a lower passage | Agree access restrictions for the drop zone |
| Shared energy | One team testing while another maintains equipment | Check affected equipment and worker withdrawal |
Duties to check and coordinate mixed work
Article 64(1)(7) of Korea's Occupational Safety and Health Act requires the principal contractor, in the applicable workplace arrangement, to check timing, content and safety and health measures for work in the same place. Subparagraph 8 requires coordination of timing or content where the specified risks may arise from mixed work. Collecting schedules and coordinating hazards are different activities.
Article 36 risk assessment includes hazards from work actions and activities as well as equipment, followed by development and implementation of improvements. New risks created by overlapping tasks must not fall outside separate team assessments. Worker participation helps reveal where tasks actually interact.
HSE recommends linking related permits and considering simultaneous and interdependent activities. Korean legal duties follow Korean provisions. Maps and interface tables support those checks; preparing a table alone does not complete coordination.
Limits of a coordination table
An interface table connects risk assessment and work permits; it does not replace equipment design or a specialist lifting plan. Check manufacturer information and applicable standards where numeric criteria are needed.