While most motorways in Queensland are divided with at least two lanes in each direction, a few motorways have been constructed as two lane, two way roads. These "half motorways" have been designed and constructed with the intent of eventual duplication to divided carriageways. This study showed that a maximum 7 second time gap between opposing vehicles influenced drivers' positioning of their vehicles. The lateral positions of cars, utility vehicles, and semi-trailers are statistically different when opposed than when unopposed; whereas, the lateral positions of B-doubles were not. This indicates that B-double drivers did not tend to move laterally when opposed by oncoming traffic. On average, passenger car drivers did not position their vehicles appreciably differently when opposed by semi-trailers and B-doubles than other passenger cars, and there was no appreciable difference in passenger car drivers' positions when faced by oncoming semi-trailers than B- doubles. The vehicle envelopes are useful to understand the impacts of heavy vehicles on driver behaviour, and can also inform road design and pavement asset management. (Author/publisher)
Abstract