On-board Mass and the Intelligent Access Program

OBM monitoring is another means to measure mass. The figure below details the main methods for mass monitoring. OBM monitoring is shown as the centre box of the figure.

The principal sensors for OBM monitoring are a combination of load cells containing strain gauges and air pressure transducers connected to the air line of an airbag suspension system.

Figure 3.2: Methods for mass monitoring

Fig 3.2

Source: Karl and Han 2007

A schematic configuration of an on-board mass monitoring system is shown below.

As shown, the mass data from the airbag suspension system is also an input for the electronic braking system (EBS), where fitted. With EBS systems, there is an air pressure transducer in the EBS module itself. The mass reading could therefore be sourced from the EBS module as well.

Figure: Methods for on-board mass monitoring

Fig 3.3

Source: Karl and Han 2007

Examples of an OBM load sensor fitment and an on-board mass display unit are shown below.

Figure: Example of an on-board mass monitoring system

Fig 3.4

Source: TCA 2009

The current Austroads IAP invites third party service providers (the private sector) to monitor in real time the compliance of heavy vehicles in following jurisdictional regulations such as speed, load and route access. In exchange for being monitored with the use of intelligent transport system (ITS) technologies such as on-board global positioning system (GPS) units, the transport industry expects to gain a concession in accessing a road network.

The service provider charges the transport industry for tracking vehicles that subscribe to the service, and also have the freight/heavy vehicle data that can potentially be another source of income. The IAP is currently in the early stages of implementation.

 Further Reading

Transport Certification Australia 2009, On-Board Mass Monitoring Test Report (Final), TCA, Melbourne, Vic

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