@monorail I think some of them work via image processing.
@monorail It's cheaper to install, since you only need one camera mounted in a convenient location instead of a loop of wire embedded under the road, but it requires more computing power than was readily available until recently.
@Rosemary i'm reading a research paper from 2007 and that seems to be the method that was proposed, yeah
okay i'm convinced i'm using the plot point :P
@monorail I'm glad my initial thought of how to do it aligns with how professionals thought to do it, then!
@monorail We don't know for sure though.