A study of almost 60 right-angle casualty crashes which occurred on South Australian roads has revealed that more than half were caused by the at-fault driver slowing or stopping, but then failing to give way.
Adelaide University's Centre for Automotive Safety Research (CASR) partnered with the state government to investigate the causes of right-angle crashes from 2014 to 2023.
Right-angle crashes, where a driver fails to give way to another road user, are common at intersections controlled by stop and give way signs.
CASR researchers investigated 57 crashes, with 37 occurring at give way sign-controlled intersections and 20 at stop-sign controlled intersections.
"There were 19 drivers who went straight through the intersection, suggesting they were unfamiliar with the road or unaware they were not on a priority road and were unaware of their requirement to give way," Research Fellow and first author Dr James Thompson said.
"In 12 of those crashes, there were advanced warnings for the upcoming give way requirements.
"Another 33 slowed down or stopped, but failed to give way, which suggests they were aware of the intersection and the need to give way, but another factor like visibility issues contributed to the crash."
The study also examined the crash histories of the intersections involved over the preceding 10 years and found that more than 20 right-angle crashes occurred at 10 of the intersections (three had 30 or more).
Specifically, 35 right-angle crashes were recorded at Kensington Road and George Street/Giles Street in Toorak Gardens, 32 at Glynburn Road and Shelley Street in Firle and 30 at Curtis Road and Heaslip Road in Angle Vale.
The list also included:
- Womma Road and Andrews Road, Penfield (24)
- Hart Street and Carlisle Street, Glanville (23)
- Main South Road and Hillier Road, Morphett Vale (22)
- Goodwood Road and Mitchell Street, Millswood; Regency Road and Humphries Terrace, Kilkenny; Cross Road and Waite Road, Urrbrae (all 21)
- Princes Highway and Copper Coast Highway, Port Wakefield (20)
"Many of these intersections have had considerable upgrades and crash prevention treatments applied, but these crashes continue to occur," Dr Thompson said.
"Our findings show that further safety improvements can include superior design that aligns with safe system principles and treatments that increase driver awareness of the intersection or reduce crash forces.
"The at-fault drivers in the right-angle crashes did not differ from at-fault drivers in other types of crashes in testing positive for alcohol or drugs, or of having passengers in their vehicles.
"This suggests that these crashes were not more likely than other crashes to result from risky driver behaviour (e.g., DUI, distraction) but, rather, that they mostly resulted from driver error and external factors such as visual obstructions, looked-but-failed-to-see errors and unfamiliarity with the road."
The report also suggested that other measures like traffic signals, roundabouts and grade-separated junctions are relatively expensive and not practical for many intersections, so there are many intersections controlled by stop or give way signs.
"The problem with intersections with stop or give way signs is that they require a higher level of involvement and judgement from the driver, who has to slow, stop or look for other vehicles before making a decision – this increases the potential for human error," Dr Thompson said.
This report was substantially completed in November 2023 and does not consider developments after that date.