ALCAM Pedestrian Model

ALCAM Pedestrian Model

Challenge
The Australian Level Crossing Assessment Model (ALCAM) is used across Australia and New Zealand to identify potential risks at level crossings and to assist in the prioritisation of crossings for upgrades. SYSTRA Scott Lister was engaged to undertake an update to the algorithm within the ALCAM pedestrian model by Metro Trains Melbourne (MTM) on behalf of the Victorian Railway Crossing Safety Steering Committee (VRCSSC).

Whilst the ALCAM pedestrian model has been used successfully for many years, to the Steering Committee sought to enhance the model and incorporate the influence of human factors on risk contribution and the ability to calculate risk using a measure of fatalities and weighted injuries.

To achieve this end the algorithm would need to be able to take account of the full range of user characteristics and behaviours relevant to all crossing types and locations and incorporate this into the model. The potential for non-compliance or error depend on the characteristics of the controls and the crossing type. Furthermore, error potential is influenced by the location and individual performance shaping factors. For example, a commuter rushing for a train at a crossing adjacent to a station may decide to cross via the adjacent road when the barriers are down, as the road protection is half barriers so easy to exploit.

Approach
The Human Factors analysis was structured around the process of the pedestrian user interaction with the crossing so that their information needs, motivations and actions could be understood in context.

The steps are:

  1. Pedestrian approaches or arrives at the crossing
  2. Pedestrian uses the affordances of the design and the information available to decide whether or not to cross (this could be either: an active gate opening/closing, visual and audible warnings or a manual check by the pedestrian)
  3. Pedestrian traverses the crossing
  4. Pedestrian exits the crossing

Benefit
The human Factors analysis formed the basis of the update to the model and was used to structure the fault trees, the model was then quantified and validated before being endorsed for use across ANZ. The enhanced model incorporates the influence of human factors on risk contribution and the ability to calculate risk using a measure of fatalities and weighted injuries. This will better inform the prioritisation of pedestrian crossings for upgrade programs and demonstrate best safety return on investment.

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