Low-doorway strikes are not controlled by displaying the opening height alone. A forklift has several changing heights: lowered mast, raised carriage, attachment, load and any free-lift movement used to clear the floor. Operators need a route rule based on the highest part in the actual travel state.
Short answer
Measure the doorway and the truck, attachment and representative load in every state that could approach it. Authorise only combinations with a defined clearance margin, require travel with the load and carriage in the agreed position, and prevent lifting within the approach zone. If a task needs a raised state to cross, the route or method needs redesign.
What this means in practice
A manufacturing site uses a triplex-mast counterbalance to move stillages through a roller door. During a production changeover, an operator raises the carriage slightly to clear floor debris and the load's top frame catches the door head. The truck stops, the doorway is unavailable and the stillage must be checked before production supply resumes. The marked mast height was correct, but the travelled configuration was not controlled.
The manager must decide whether the obstruction should be removed, a lower-profile load or truck used, the route changed or the task prohibited. Repeating “lower the forks” is insufficient if damaged flooring or load construction makes operators raise them again.
Key checks
- Measure clear opening height at the lowest point, including door furniture and hanging services.
- Record lowered mast, raised carriage, attachment and representative load heights separately.
- Mark a no-lift approach zone that gives time to correct the travel state before the opening.
- Check floor slopes, debris and thresholds that cause operators to alter fork height.
- Review scrape position to identify whether mast, carriage, attachment or load made contact.
Site-specific familiarisation should require the operator to demonstrate the approach using the real truck and load type, not merely acknowledge a sign. Supervisors also need a rule for unusual loads, hired trucks and maintenance changes that alter height.
Common mistakes
Using the truck brochure's mast height as the only figure ignores raised carriage and load projection. Another mistake is placing a warning sign directly above the opening, where the operator sees it too late to lower safely or stop without blocking the route.
What good looks like
An approved-clearance register identifies each truck, attachment and load combination permitted through the opening. The approach is kept clear, lifting is prevented within the marked zone, and operators demonstrate the correct travel state during familiarisation. Managers can explain the measured margin and immediately reassess it when a hired truck, new attachment or taller load arrives.
When to ask WRMH for help
Ask WRMH when overhead marks repeat, truck or attachment changes make the clearance uncertain, or operators need a raised position to negotiate the approach. WRMH can verify truck and mast dimensions, inspect contact damage and provide task-specific familiarisation or training. That helps the site choose a defensible equipment, route or competence control before another strike interrupts the doorway.
Helpful next step: measure the highest point of the actual travelled load and carriage position, then compare it with the lowest point across the full doorway width.