Here's my opinion on this checkpoint. The other Saturday I headed to Leavenworth for the Xmas lights. We drove the whole way with minimal traffic.

We got to within 3 miles of town and boom, traffic jam. We waited 3.5 hours until we got to the source of the traffic jam, it was a 4 way stop sign.

Putting an individual at a checkpoint looking for traction devices would have a similar effect. I don't see any good solutions evident.