Heavy vehicle productivity: Being smart about getting heavy – PBS vehicles and bridge loading

High gross masses can mean potentially high bridge impacts, which naturally worries road owners and managers……but some heavy vehicles can be unfairly restricted. Pushing the boundaries of heavy vehicle productivity means more than just designing a vehicle to meet the bridge formula, and Advantia can show you smart methods of achieving real productivity gains.

Bridge capacity is one of the main reasons for limiting heavy vehicle gross combination mass. Bridges have the longest lifespan out of all types of transport infrastructure, and most were not built to accommodate the types of highly-productive and innovative heavy vehicles coming through the PBS system.

This has the potential to leave operators in an unfortunate scenario. Vehicles meeting the PBS standards are ‘knocked back’ at the access approval stage by road owners fearful that they will cause excessive loads on bridges, and seriously impact bridge lifespan.

Situations like these can be avoided by being smart about getting heavy. At Advantia, this means using engineering analysis techniques to sort out potential bridge issues as part of the vehicle design process, so that there are no headaches later on down the track when it comes to applying for permits to operate.

Advantia’s smart analysis goes one step further than simply ensuring that a vehicle meets the PBS ‘bridge formula’. In fact, heavy vehicles can fail the bridge formula, but still be permitted access to some roads. This is achieved by assessing the impacts of the vehicle on bridges against the impacts of suitable reference vehicles, which are generally existing ‘as-of-right’ B-doubles and semi-trailers.

In most cases, it can be shown that the impacts of the new vehicle are in fact less than, or at least equal to, the reference vehicles, meaning that the new vehicle should be no more damaging to bridges than vehicles that are currently permitted to operate.

If the analysis shows that the new vehicle imposes greater loads than the reference vehicles on bridges of certain lengths or construction type, Advantia uses bridge inventory data to check if the routes where the vehicle will operate contain such bridges. If not, then there is no reason why the vehicle should be restricted from that route.

For example, an A-double loaded to 80 tonnes gross mass can be shown to have equal or less effect than a HML B-double at 68.5 tonnes gross mass, for bridge spans shorter than 10 metres. This means that an A-double that meets the PBS standards could be operated on Level 2 HML routes at 80 tonnes, provided that the routes do not include any bridges with spans longer than 10 metres.

To find out if your vehicles could achieve higher gross masses without sacrificing any road access, contact Advantia today and see how our smart methods can help you achieve real productivity gains.