Optimizing Counts: Under Count in First Zone Past a Barrier

In the situation shown below, the count for zone 4 is lower than what is expected.

This is a picture of the software.

The above could indicate there is some kind of barrier between zones 3 and 4. The signal from the barrier is imposing on zone 4, causing smaller vehicles to be missed. Moving the zone boundary away from the barrier should help resolve this situation. Fine tune zone 4 by moving the zone boundary closest to the barrier further away from the barrier. A slight adjustment can make a large improvement.