Segregation Hierarchy
The people-plant interface is one of the biggest causes of fatalities on UK construction sites. HSE guidance (HSG144) and the CLOCS Standard require a hierarchy of controls to manage the risk of pedestrians being struck by mobile plant.
Eliminate
Remove the need for people and plant to be in the same area. Can the task be done without pedestrians present? Can materials be delivered outside working hours?
Separate
Physical barriers between people and plant. Dedicated pedestrian walkways, fenced exclusion zones, separate site entrances and exits.
Safeguard
Proximity detection and warning systems. Radar, ultrasonic sensors, AI cameras, tag-based systems that alert the operator when people are nearby.
Warn
Lights, beacons, reversing alarms, horns, signage. These alert pedestrians but rely on them seeing or hearing the warning.
PPE (Last Resort)
High-visibility clothing. The least effective control — it only works if the operator can see the pedestrian and react in time.
Blind Spots by Machine Type
Every machine has areas where the operator's direct vision is restricted or completely blocked. Understanding these blind spots is critical for both operators and pedestrians.
| Machine Type | Key Blind Spots |
|---|---|
| 360 Excavator | Rear and offside of the machine, directly under the boom. The counterweight blocks rear vision almost entirely. |
| Forward Dumper | Behind when loaded — the skip restricts the operator's rearward view. Also limited visibility to the sides when skip is raised. |
| Telehandler | Right side (nearside), directly behind, and overhead when the boom is extended with a loaded attachment. |
| Roller | Both sides and the rear. The drum width creates wide blind spots at the front corners. |
| Loading Shovel | Directly behind and in the bucket area when the bucket is raised. Side visibility restricted by the cab pillars. |
Visibility Aids
Modern visibility aids supplement the operator's direct vision but should never be relied upon as the sole means of detecting pedestrians.
- CCTV cameras — rear-view and 360-degree camera systems provide the operator with a live view of blind spots on an in-cab monitor.
- Radar / ultrasonic sensors — detect objects in the blind zone and alert the operator with audible and visual warnings in the cab.
- AI person-detection cameras — use machine learning to distinguish people from other objects, reducing false alarms compared to basic radar.
- Tag-based systems — pedestrians wear electronic tags that are detected by the machine's proximity system. Effective in controlled environments.
- Mirrors — convex mirrors improve side and rear visibility but can distort distance perception.
- Reversing alarms — audible warning when the machine is in reverse. White noise (broadband) alarms are preferred over tonal beepers as they are easier to locate directionally and cause less nuisance.
Banksman Protocols
A banksman (signaller) guides plant movements in areas where the operator's visibility is restricted. Effective banksman operations require clear protocols:
- Positioning — the banksman must be visible to the operator at all times and positioned in a safe location outside the machine's travel path.
- Hand signals — standard signals as per BS 7121 (for cranes) or site-specific signals agreed before work begins. Signals must be clear and unambiguous.
- Radio communication — used as a supplement to hand signals, not a replacement. The operator must confirm each instruction before acting.
- CLOCS standard — the Construction Logistics and Community Safety standard requires banksman training, vehicle safety equipment, and planned routes for all construction vehicles on CLOCS-compliant sites.
Key principle: If the banksman cannot be seen by the operator, ALL machine movement must stop immediately. The operator should never move the machine without clear confirmation from the banksman.
People Plant Interface Study Guide
In-depth study material covering all aspects of people-plant segregation for your CPCS renewal test.
