In our last post we discussed the need recognized at the Automated Vehicle Symposium for varying levels of vehicle autonomy based on the road and current conditions. One of those conditions is clearly work zones. A car may be able to operate at Level 4 autonomy in freeway traffic, but may have difficulty ding the same in some work zones.
In those cases we must signal the vehicle to alert the driver to prepare to retake control. And that warning will have to be given leaving sufficient time for the driver to become cognizant of the dangers around his or her vehicle. A poster session at the AV Symposium by Chris Schwartz of the University of Iowa looked at that timing. Their study focused on large trucks and found drivers needed as much as 10 seconds to get their wits about them for normal driving. Work zones should probably allow a little more time, as drivers may have to start immediately to negotiate lane shifts, narrow lanes, or other challenges. So ideally this signal would come at about the first construction area sign (ROAD WORK AHEAD).
The conventional method would occur through the cars digital map. That will be how other hand-offs take place, such as when driving from a roadway capable of supporting level 4 automation to an older stretch only capable of supporting level 3. But those are points that rarely move or change. Work zones may only take place for a few days, or a few hours. As we have discussed in past posts, the map must be updated in real time for features like this to work correctly.
Manufacturers are working today on beacons, arrow boards, and more that will signal when lane closures begin and when they end. This is already happening today and will only become more popular as smart technology is accepted in more and more work zones.
But another option was mentioned in the same session. 3M is experimenting with a way of placing two-dimensional bar codes within their reflective sign sheeting. The bar codes are only readable by infrared cameras. Drivers would never see them. They would just see the static sign saying something like ROAD WORK AHEAD. But the car they are driving would be triggered to return control to the driver.
This technology is in the very early stages of testing. 3M has signs up on freeways in Michigan now and hopes to test more of them in the Bay Area of California soon. It is too early to say this is a solution but it does show promise. A combination of map triggers and these signs would provide some redundancy and might also be a simpler way of notifying drivers of very short term work zones such as those installed by utility companies and smaller agencies.
The good news is that both the traffic control industry and the AV industry recognize the importance of this hand-off prior to work zones and they are working to find solutions.