In July 2021, a truck deflected into the path of an oncoming vehicle after its load exceeded the safe height clearance for the route being driven. The driver was killed. The investigation that followed found that despite the driver’s experience, there were no recognised industry standards or formal training for measuring truck load heights — a gap that the judge found directly contributed to the incident.
Load height is one of those risks that can seem routine until it isn’t. Trucks travel under bridges, through tunnels, past overhead utilities, and through underpasses every day without incident — until the load is too high, and then the consequences can be catastrophic and irreversible.
The Legal Framework
The Land Transport Rule: Vehicle Dimensions and Mass sets the maximum permitted vehicle height in New Zealand at 4.25 metres for most vehicles. Loads that exceed this height require a permit and must follow a specific route approved for overheight transport. The permit system exists because routes are surveyed for clearances — but that only works if the measured height of your load is accurate.
Where Measurements Go Wrong
Load height errors occur more often than the industry acknowledges. Common causes include:
- Measuring the vehicle height without accounting for the load, or measuring only the load without accounting for the vehicle
- Loads that shift or settle during transit, changing the height profile
- Failure to account for road camber, which can change the effective clearance on a curved road
- Inaccurate measuring tools or technique — an extending tape measure used incorrectly can introduce significant error
- Relying on manufacturer specifications rather than physically measuring the actual loaded configuration
What Operators Must Do
Every transport operator whose loads approach the permitted height limit should have a documented measurement procedure that is consistently followed. This includes: measuring from the road surface to the highest point of the load with the vehicle on a level surface; accounting for tyre pressure changes; cross-checking against route clearances for the planned journey; and documenting the measurement with the date, measurer’s name, and reading.
For construction companies that regularly transport plant and materials, the management of overheight loads is a health and safety obligation under the Health and Safety at Work Act 2015. A documented procedure, trained drivers, and consistent compliance checks are the minimum standard. The legal and human consequences of getting it wrong are severe.