Static Rollover Threshold (SRT) 3 Axle Truck and 3 axle Trailer

Over weight policy allows for Overweight permits can be issued for the transport of Sealed containers for export/ import. Weight per axle can not exceed 1.1 times the normal class 1 limit (1.1 VAI) Theoretical Maximum Gross weight can be up to 44 tonne. Vehicle must have a current SRT certificate issued by a certifying engineer

Historically Trucks have been able to carry 29+ tonne containers and weigh in on their axles Certifying engineers used Freight density to calculate the SRT on long term area permits.

Exert from NZTA letter KA-CIRCS Within the three months, the companies involved will need to demonstrate SRT compliance for Uniform Density loads to get their permits reissued. If they can demonstrate SRT compliance with the SRT requirements at Uniform Density they can get the permit reissued.

The Issue The NZ Transport Agency has advised a change to the method of calculating SRT “Uniform Density” replaces“Freight density” This method will arguably limit all 6 axle container combinations to a maximum payload of 25 tonne. 6 axle trucks are by far the most dominant configuration in the NZ container transport fleet The physical number of alternative 8 axle configurations are not sufficient to satisfy market requirements.

The effect of height “v” weight

Practical consequences for the Kiwifruit industry For the Kiwifruit industry would need at least an extra 500 containers per year to ship the same volume Several million dollars of additional cost (mostly paid to shipping companies so the money goes off shore) If we have to load additional containers for the same volume we may struggle to secure additional equipment at short notice.

Technical stuff Freight Density recognises that the load in a container is not completely uniform inside the container so the centre of gravity is lower Uniform Density says the container is completely loaded top to bottom and end to end so the centre of gravity is higher. Other For all other loads for a particular height above ground level of the centre of gravity of the load, the maximum allowable gross mass of the vehicle must be determined

Reasons that have been communicated which instigated the change Police have indicated that there have been a number of container trucks roll over. Police maintain that they can not see inside the container to see the height of the load so the top of the container must be treated as the top of the load

NZTA’s Responsibility’s under the Vehicle Dimension and Mass Rule 2002 To achieve a reasonable balance between the risks that heavy motor vehicles present to public safety, and the efficient operation of the heavy motor vehicle fleet within the constraints imposed by the road network”. Due consideration for the safety of the vehicle, road users and the durability of roads and bridges