How Nissan leveraged its driver assist to cut traffic jams

"Instead, CCM works by having a lead car, or "probe," send information to following CCM-equipped cars, which are separated by non-CCM cars between them. The information from the probe car lets the following cars keep an appropriate distance from each other-between 30 and 60 seconds-and if there's a slow down ahead, the following cars will decelerate more gently over time, preventing the kind of concertina action that triggers traffic jams when human drivers see someone slowing down in front of them."

"So we did spend some time to balance this phenomenon and the performance of our system. So there's some parameters we continue to control to balance this," Chou told me."

"So in our simulations we tried different penetration rates... and we saw that our benefits increase proportionally to penetration rates. But we already can see some good results at around 4-5 percent penetration," Chou told me. "But you know, that's actually one challenge of experimental. Since our experiment only has a few cars, we have been thinking about how to control just these few cars to see some results."

Cooperative Cruise Control (CCM) uses a lead probe car to send information to following CCM-equipped cars separated by non-CCM vehicles. The probe data enables following cars to maintain 30–60 second spacing and to decelerate more gradually when slowdown occurs ahead, reducing concertina effects that trigger traffic jams. The cars communicate via embedded LTE modems and Nissan's cloud rather than DSRC. Engineers tune following-distance parameters to balance preventing cut-ins with system performance. Simulations show benefits scale with penetration and visible improvements appear at roughly 4–5% CCM-equipped vehicles. Future work includes giving drivers feedback and licensing CCM to other automakers.

Read at Ars Technica