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Traffic Engineering assigned this issue to Scott Brunner

Good Morning,

Thank you for providing the information at these two intersections.

Yes, we have responded to about 20 similar inquiries as the in-road loop detectors were destroyed during the initial cutting and milling of the asphalt early in the Hardscrabble Road project. For several technical reasons, the in-road loops are not reinstalled until the new final course of asphalt is installed, and therefore the loops have been substantially non-operational for about a year while the project was under construction. We admit this has been not convenient or ideal, and we have monitored the situation and programmed several sets of fixed-time timing plans during construction. New loops were installed just before start of school, but they were not connected properly by the contractor and again were non-functional. Our staff is working with the contractor to reconnect the loops in the proper manner, and that work is nearing completion. Operations should improve in the very near future. We regret that this proceeded this way and will be looking at how future contracts are written in order to minimize these situations. We appreciate your patience.

With regard to your comment about detection, most signal systems in American (including ours) actually operate with the major street remaining in the green phase ("resting" in green), and then changing to red only when vehicles are detected on the minor streets and minor turning movements. However, there is no perfect detection system or sensitivity algorithm to account for all detection situations and sometimes vehicles trip the sensor and clear the intersection (such as a right turn), but the detector puts a call into the side street nevertheless. There are setting and programming that try to interpret what is happening, but they are not perfect. We also attempt to set the sensors with high sensitivity so that they may tend to over-detect rather than not detect. Pedestrian phases also create red phases for the major street vehicles may not be evident to drivers. Motorists waiting on a red with no vehicles coming from the side street assume a detector is bad but many times a pedestrian call was placed. A pedestrian phase must be a set fixed-time interval by law, and therefore there may be no cars coming on the side street while a pedestrian is still crossing or may have completed their crossing.

With regard to police officer control, that type of control is probably the most ineffective method of traffic control because despite the great and dangerous job they perform, they can only see what is happening within their view and cannot address what is approaching or departing from other intersections around them. For certain simplistic situations at a school, for example, they can work pretty well, but its still not ideal because they may be sending large groups of traffic towards the adjacent traffic signals at the less optimum time. We work closely with the Police Traffic Enforcement Unit here, and they will probably tell you the same thing.

Traffic signal operation is going to evolve and change rapidly over the next ten years, and signal network control is likely to be guided by positional signals emitted from individual vehicle onboard systems (Bluetooth, etc.) rather than physical detectors in the roadway, or possibly a combination of both. Autonomous vehicles will have to rely on the onboard positional systems and superfast communications rather than the detectors and signal control technology we use today. Traffic signals will probably cease to exist in their current red-yellow-green form. The new technology is here, its been proven in the lab and on the road to a limited extent, but the infrastructure has yet to be built.

Hope that helps answer some of your questions. We always appreciate the feedback.

Scott Brunner, City Traffic Engineer
sbrunner@roswellgov.com

The new paving at the approach lanes of these intersections with the damaged loops have been completed, and new in-road loops will be installed within the next few days. This will bring the intersections back up to their pre-construction state with active vehicle detect for all turning movements. We appreciate everyone's patience.

-Scott Brunner

Closed by S. Brunner