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Chapter 1 Introduction

1.1 Background

Heavy vehicles contribute significantly to the Australian economy because they are the major
means for transporting goods within the country. Activities involving heavy vehicles were

projected to double from 2000 to 2020 as a result of transporting goods in Australia (Manders
2006). In Australia, over 75% of the non-bulk domestic freight is carried on the roads,

dominating freight between large cities, and it is predicted that truck traffic will increase by
around 50% by 2030 (DIRE, 2014).

The average annual growth for Melbourne city road freight was approximately five per cent
for the period between 1971 and 2003, and it is estimated to grow from 10.3 billion tonne-

kilometres in 2003 to 16.9 billion tonne-kilometres in 2020. Therefore, the increase in road
freight will increase the share of heavy vehicles in traffic, which will consequently increase

the possibility of crashes involving heavy vehicles. The increasingly high share of truck

traffic has generated some safety concerns, as the probability of a traffic collision is estimated
to increase by 5% when the percentage of heavy vehicles is more than 30% of the total traffic

volume (Moridpour et al., 2015).

Moreover, the likelihood of a severe outcome (fatality and serious injury) is much higher

when a heavy vehicle is involved in a traffic collision. The larger size and mass of a heavy
vehicle contribute significantly to the injury severity of small vehicle occupants in a multi-

vehicle collision (Smith, 2000). The number of fatal injuries among the smaller vehicle
occupants is twice that of the heavy vehicle drivers in collisions involving a heavy vehicle

and a smaller vehicle. Hence, traffic collisions involving a heavy vehicle are not only a safety
concern for heavy vehicle operators, but for all road users.

Despite the small proportion (approximately 3%) of registered heavy vehicles in the total
traffic, fatalities from collisions involving these vehicles are 18% of the total road fatalities in

Australia (ATC, 2011). Moreover, in the past three years, the number of fatal injuries
involving heavy rigid trucks increased by 8.5% each year between March 2012 and March

2014 in Australia (BITRE, 2014). Hence, traffic collisions involving heavy vehicles are a
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