170
Just for counting? For speed also?
(lemmy.world)
Let us help you identify that mysterious object you’ve found.
Currently in CHALLENGE mode: If you've got something obscure knocking about, post a picture, and let's see how we do. Please prefix such posts with "CHALLENGE:" so we know we've got a fighting chance.
For counting or for speed? You can't really measure speed with one because of that issue, but you easily can with two. For counting it's probably good enough to count pulses and divide by two. Sure, some trucks have more than one axle, but it might not matter. Plus I'm guessing with enough data they have a signature of what multi-axle vehicles look like.