A diverging diamond interchange is a type of road intersection commonly used in the United States and it is currently being explored as a viable option for Australia’s road network. Under the design, two directions of traffic on a non-freeway road cross to the opposite side on both sides of a bridge at the freeway.
The concept is being considered for Victoria and Queensland, but there are some important questions about exactly how it will perform.
While it’s an established road design in the US, the diverging diamond interchange concept has never been used on Australian roads. What’s more, the interchange is based on drivers on the right-hand side of the road. For this reason, it is important to investigate how drivers behave in a drive-on-left scenario.
These problems are being addressed directly through ARRB Group and Curtin Monash Accident Research Centre’s (C-MARC) new state-of-the-art road simulator – the CKAS Mechatronics simulator.
Western Australian Deputy Premier and Minister for Road Safety Liza Harvey officially launched the simulator in April, and it is housed at Curtin University’s Technology Park campus.
Paul Roberts, ARRB Group Principal Behavioural Scientist, says that the new CKAS Mechatronics simulator will enable the university and road research group to undertake complicated driver behaviour and road infrastructure research.
“What we’ve got here is one of the most thorough simulators around. It’s probably the most advanced in the southern hemisphere and we’ve fitted it some very sophisticated software,” says Dr. Roberts.
Inside the simulator pod are 360-degree screens and a fully functioning Kia car, complete with transmission, clutch, brake, accelerator and power steering system. “We have a lot of perceptual information and a lot of movement that is similar to driving an actual car,” he adds.
The pod has a moving base and uses hydraulics to simulate the real thing, moving up and down and creating an “immersive” environment, as Dr. Roberts puts it.
While other universities and research institutes around the country use driver simulators for research purposes in the fields of driver distraction, safety and driver behaviour, the CKAS Mechatronics simulator exceeds the boundaries of static simulations for researching driver behaviour and has many applications for road design.
For nearly 12 months, the research team has been developing scenarios that make the machine unique. As Dr. Roberts explains, the software is made up of complicated algorithms that simulate the driving environment. The research team can control and manipulate variables, including the behaviour of virtual traffic, pedestrians and weather conditions. They can create scenarios within the simulator based on road designs, which can then be tested from the driver’s point of view.
These scenarios can be created using CAD drawings, enabling realistic simulations of the intended road design to be accurately recreated.
Using the simulator for road design allows for more comprehensive research and planning when it comes to new road concepts, such as the diverging diamond interchange. Furthermore, they can be tested and experienced stringently from a driver’s point of view to ensure the concept is viable for the country’s roads. “The ideal thing about using the driving simulator is that we can design the road, simulate it, and then build it. That’s not just improving things in a safety context, but efficiency too, and no one’s doing that in Australia,” says Dr. Roberts.
Dr. Roberts says that the research team’s aim is optimise road design from a safety and efficiency perspective, as well as a cost savings one too. Rather than building the road itself and realising there are a few issues to work out, he asserts that preliminary steps can be taken in the simulated environment to test its suitability for Australian roads and drivers.
Following testing, any resulting changes to the design can be made easily. “The simulator’s a great way to try and figure out issues that come up that people don’t think about. It’s an underused tool in the realm of road design,” says Dr. Roberts. He adds that the simulator has potential applications in stakeholder engagement when it comes to road design.
The research team is now actively compiling an extensive library of road scenarios. Once a large catalogue of scenarios has been collected, Dr. Roberts says it will be much easier and cheaper to simulate new road designs and situations, as there will be multiple simulations to draw information from.
Dr. Roberts says the simulator already has some good quality visual scenarios in the system, and they’re currently creating environments using actual Australian roads. “We’re building up a library of Australian appropriate kinds of scenarios and we’re starting with roads in Western Australia,” he says.
Using real Australian roads means the environment is as realistic as it can be. However Dr. Roberts says it’s hard to keep them up to date as aspects can change over time.
The research team is now looking at working with GPS-based systems, such as Google Maps or video capture feeds, where they can simulate real and up to date roads. “If Main Roads was to change the network in some way, we could put people through the new changes and test it first.”
The ARRB and C-MARC research team is already engaging with road authorities on a number of projects. These include the prospects for diverging diamond road interchanges on Australian roads and driver distraction with digital billboards with Main Roads WA.
Dr. Roberts says another use for the simulator in the future is for research into driverless vehicles. “One of the bigger challenges is not in how to design roads for just driverless cars,” he says. “There are quite a lot of questions about how driverless vehicles and semi-driverless vehicles will interact, and what kinds of things need to be designed and considered.”
Dr. Roberts concludes that there is plenty of potential for the simulator in the realm of road design – it’s an application not widely seen around the world. He says that it still requires a great deal of development, but they are already attracting interest from road authorities in how it can be used to assist in the future development of Australia’s road network.
“We’re really looking forward to getting our teeth into this side of it. It’s really ARRB’s bread and butter.”