Autonomous vehicle technology trials currently underway in Victoria have delivered a first round of results, revealing aspects of infrastructure and technology that must be improved for autonomous systems to reach their full potential.
Using current-model vehicles with ‘level 2’ autonomous technology systems already in market, the trials were first announced in December and have been actively testing in regular daily traffic on the Eastlink corridor.
Cars for the trial have been provided by BMW, Honda, Mazda, Mercedes-Benz, Mitsubishi, Tesla and Volvo, with Audi and Toyota to join soon. The project is being carried out by roads company Eastlink, with VicRoads, the Australian Road Research Board (ARRB), La Trobe University and RACV.
Announcing the first-round results today, Eastlink said in a media release that the trials “have produced real results for freeway operators and vehicle manufacturers to facilitate the safe and early introduction of this capability on EastLink and other Victorian freeways”.
Takeaways from the results included some already long understood, including the need for consistent and highly visible line markings and signage. The temporary yellow lines used in construction areas also proved confounding for the systems tested.
A full list of the learnings, provided by Eastlink, is below.
Good quality of line markings – including reflectivity and luminosity – on both sides of the lane are essential to avoid “drop outs” of the lane keeping assist function, and to help a vehicle maintain its position centrally in a traffic lane.
Gaps in contiguous line markings should be avoided, as this may lead to drop outs of the lane keeping assist function or unintentional lateral movement.
In construction zones, the use of temporary yellow line markings conflicting with white line markings is incompatible with the lane keeping assist function, causing drop outs. The automated functions in different vehicles may drop out with varying amounts of advance warning. When planning traffic management for construction zones, road operators will need to consider whether lane keeping assist dropouts are acceptable, on a case by case basis.
Consistency of speed signage (format and placement) and maintaining line of sight visibility will enable more reliable interpretation by vehicles.
Speed signs on freeway exit ramps or side roads need to be located well away from the main carriageway so they are not confused for main carriageway signs.
Conflicting or confusing speed signs should be avoided, as vehicles find it very difficult to determine the correct speed limit under these circumstances. This could occur within a construction zone where there is poor implementation of traffic management plans, or in circumstances where static signs show that different speeds apply to different vehicle types or at different times of the day.
Variable speed signs are increasingly deployed on Melbourne’s freeways. Roadside variable speed signs are read very well by some vehicles, while other vehicles are not yet reading them reliably.
The flashing annulus feature on variable speed signs (when speed is lower than normal) is not expected by some vehicles, impacting recognition. In general, overhead variable speed signs, which are an increasingly common format on Melbourne’s freeways, are not yet read reliably by vehicles.
Lane control signs:
Overhead lane control signs (designating a lane open or closed) are increasingly common on Melbourne’s freeways. However, they are not yet recognised and used by vehicles.
It is hoped that these results will help manufacturers and third-party development groups to refine their autonomous technologies, in the lead-up to anticipated legislation that will – at some point – make hands-free driving legal and safe on specified roads, in certain conditions.
Likewise, Eastlink has repainted the line markings on sections of its roads – partly, it says, to improve visibility in all conditions for current-model vehicles using existing ‘level 2’ autonomous systems like lane departure alert and lane-keep assistance.
“With Level 3 hands-off-the-wheel driving on the way, it’s envisaged that freeway operators will need to communicate directly to autonomous vehicles, for example to communicate a change in conditions or operating environment (e.g. emergency incident, congestion event, or lane/tunnel/bridge/freeway closure),” Eastlink says.
Communication technologies are expected to play a crucial role in the safe operation of future semi- and fully-autonomous vehicles, and indeed many groups are now referring to autonomous vehicles more specifically as ‘connected autonomous vehicles’, or CAVs.
The communications technologies needed for this future of autonomous driving are known, depending on the criteria and design, as vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I), or collectively as vehicle-to-everything (V2X).
The field, as a whole, is generally referred to as ‘intelligent transport systems‘, or ITS.
To accommodate the communications phase of its trials, Eastlink is installing transceivers on three of its tolling gantries. The initial focus will be to confirm that the 5.9GHz band mandated for ITS is compatible with the 5.8GHz dedicated short-range communications band used by tolling tags.
“Next, we will learn about the type of message that should be best communicated by EastLink’s freeway infrastructure to connected vehicles, and the optimum parameters for those infrastructure to vehicle communications,” spokesperson Doug Spencer-Roy said.
“Vehicles with advanced driver-assistance technology are now being released in Australia. Within the next few years, once legislative changes are made, we expect vehicle manufacturers will activate hands-off-the-wheel driving capabilities on EastLink and other suitable freeways. These EastLink trials are producing practical results that will assist with that transition to hands-off-the-wheel driving.”
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