The use of right turn filters provides improved intersection efficiency, although results in higher rates of ‘right through’ and ‘cross traffic’ crashes. This research paper aims to quantify the effects on road safety of the use of right turn filter movements at signalised intersections.
This research examines 77 traffic signal site with 147 approaches with right turn filtering enabled throughout the greater Sydney metropolitan, Newcastle and Wollongong areas. This research looks into factors influencing crash rates at these intersections including speed, number of opposing lanes, traffic volumes and characteristics of the right turning driver including gender and age.
It was found that the opposing traffic volume has a large impact on both the ability for drivers to undertake right turn movements and the rate of ‘right through’ crashes. It was found that at opposing traffic volumes between 100 to 300 vehicles per hour per lane results in the highest rate of ‘right through’ crashes. Above 300 vehicles per hour the ability to undertake opposed right turns is very limited and the right turn filter benefits of improved traffic efficiency are non-existent.
The crash data indicates that young drives (17-29) are much more likely to be involved in ‘right through’ crashes than any other age group. The occurrence of ‘right through’ crashes decreased as the age of the driver increases. It was found that as the age of the drive increased their risk of crashing at a signalised intersection with right turn filters enabled decreased. There is no indication that older drivers (>60) have an increased crash risk at these intersections. In fact, the data shows that driver in this age bracket have the lowest crash risk of all ages
