When work zone safety professionals discuss automated and autonomous vehicles, one question always comes up. How quickly can a driver who is not driving take control of the vehicle, understand what is expected of him or her in a work zone, and then safely guide their vehicle through it. This was a subject of discussion at the ATSSA Innovation Council meeting last month.
Marty Weed, Work Zone Traffic Control Engineer for Washington State DOT, has since suggested that much more research needs to be done in this area. In many ways, the hand-off from automated control to full driver control is the ultimate test of any system.
Marty referenced a study conducted last year by the Virginia Tech Transportation Institute entitled, “Human Factors Evaluation of Level 2 and Level 3 Automated Driving Concepts.” (US DOT publication DOT HS 812 182). Vehicle automation runs from 1 (no automated control) to 4 (completely automated control). They focused on levels 2 and 3 where some control was present but the driver, or operator (as they now refer to the person behind the wheel), must resume control within varying amounts of time.
Level 2 Automation “involves automation of at least two primary control functions designed to work in unison to relieve the driver of control of those functions. Vehicles at this level of automation can utilize shared authority when the driver cedes active primary control in certain limited driving situations. The driver is still responsible for monitoring the roadway and safe operation and is expected to be available for control at all times and on short notice. The system can relinquish control with no advance warning and the driver must be ready to control the vehicle safely. An example of combined functions enabling a Level 2 system is adaptive cruise control in combination with lane centering.” Because the driver is expected to remain in full control, few problems were noted.
However, Level 3 Automation allows the driver “to cede full control of all safety-critical functions under certain traffic or environmental conditions and in those conditions to rely heavily on the vehicle to monitor for changes in the conditions requiring transition back to driver control. The driver is expected to be available for occasional control, but with sufficiently comfortable transition time. The vehicle is designed to ensure safe operation during the automated driving mode. An example would be an automated or self-driving car that can determine when the system is no longer able to support automation, such as from an oncoming construction area, and then signals to the driver to re-engage in the driving task, providing the driver with an appropriate amount of transition time to safely regain manual control.”
Of course, this assumes the vehicle knows where all work zones are located, or that the vehicle somehow knows to relinquish control when orange signs, cones, or arrow boards are encountered. Additionally, the study found drivers needed about 5 seconds to acclimate themselves to the unexpected conditions and to transition to full control. So it seems that the only practical design would have to be based on perfect knowledge of work zone locations. Otherwise the driver would not have those 5 seconds to take control.
The work zone industry has the technology to provide that knowledge today. But testing of that technology and of the reaction to it by automated vehicles should begin immediately. It will take several years to prove it works and to deploy it nationwide.
Click HERE to download the study.