Pedestrian Detection Improvements?

Pedestrian Pushbutton Supervision.

I walk around a lot and pass through traffic signals often. All too often, when I push the pedestrian push button (PPB), there is no response. Now this type of failure should be caught during a regular maintenance check but they can easily happen at any time. How can these be made to operate in a failsafe manner.Simple, supervise them. There are basically two types of common failures for any PPB. The switch is stuck open and wont actuate the signals or the switch is stuck closed and the pedestran service happens every cycle. The latter type of failure is usually reported more quickly than the former.

We tried a test system of PPB monitor cards that detected both failures but the test wasn’t sucessful due to maintenance problems. Each PPB required the installation of a dongle across the contacts and additionally, we had a really bad batch of PPB’s. The test was abandoned and we never got back to the project.

Here are my current ideas on the subject.

The system should detect too long of an actuation or no actuation. The system should detect the presence of all PPB’s and identify wiring problems similar to a firealarm system. It would be best if most of the inteligence were in the controller for easier management.

It would be nice if no field wiring or hardware changes were necessary but that, most likely is not possible. One possible method is using a loop current but that still might not detect all failures. An intelligent device at the pushbutton that actually communicates back to the controller cabinet would be best. Wireless devices might find a use in this application. It might be best if the existing field wiring and general PPB functions remained the same with the monitor function as a supplemental feature.

PPB Feedback:
The above monitoring would also go well with better user feedback. It would be nice if the user got confirmation of a successful pedestrian call received by the controller. There have been systems that provide some feedback but they usually just used field conditions and not feedback from the controller. This might reduce the wear and tear on the PPB by eliminating the multiple actuations that many people use to assure they get service and as some people seem think, to get service more quickly.

When the pedestrian pushes the PPB, a light could indicate the call had been received using some form of communications over the existing wiring such as a voltage change.

Alternate Pedestrian Timing Selection:

Now for another idea. How about providing different pedestrian timing based on the type of actuation. Some pedestrians need additional time. Elderly people, School crossing guards, Handicapped people and ? Allow a longer continuous actuation of the PPB to be recognized by the controller as a need for longer service. Select an alternate walk interval if say the PPB is held for 5 seconds or something similar. Again, this would provide for a potentional need without undue impact of the other users of the signal.

These aren’t all the possibilities and some may be in use somewhere but I think it wouldn’t hurt to try to see if there isn’t some better way to serve the customers.