Sounds like this technique can be imperfectly implemented without any new technology.

Just encourage people to use defensive behavior when they see a jam up ahead, and optimistic behavior as they leave the jam.

Sure, that's limited to people's line of sight (in the case of approaching the jam), but it's better than nothing.

Interestingly, I've been assuming both optimal behaviors intuitively. When I see a jam up ahead, I slow down well ahead of time, hoping that by slowing now, I'll avoid a full stop up ahead; similarly, as soon as I get out of the jam, I speed up quickly. Seems like the natural thing to do after a traffic delay.