@Marko - Yep, that's us.
We've been experimenting with the use of light duty tube counters on local trails for much of the summer. We did our first trials on the Steel Heritage Trail in June or July, experimenting with different types of equipment/configurations/etc., and comparing the data to the numbers generated by our older infrared counter, which we know to be slightly glitchy. We also positioned a person out there to conduct counts, to provide "field verification" of the tube count results.
We think we have a configuration that works. We took it out to the Millvale Trail, and the South Side Trail earlier this month. We currently have three counters deployed on the Eliza Furnace Trail. Two are the traditional tube counters that we would use for roadway counts, but set up with lower resistance tubes, to ensure that bikes are counted. The other is a new counter we bought specifically for its ability to count bikes. By having all three out there simultaneously, we can compare the results, and refine our equipment configurations to generate the most accurate results.
Once we are satisfied that we have the right "mix" of equipment, we'll be working with the Friends of the Riverfront and other trail groups to conduct weeklong or two week long counts of bicycle activity on the local trails. Obviously, that will tell a different story than the one we generate from the peak hour/rush hour counts that we complete twice each year.
So, if you see those tubes on the trail, ride over them, not around them. And, strangely, they work better or are more apt to pick up a cyclist moving at speed than a cyclist that is dawdling. We figure the "speed of certainty" in making sure we get the count is about 8 mph.