Traffic Cops
My bus line to work goes along one of the bigger traffic arteries of central Athens. On some days when traffic thickens, someone from the τροχαία (trohaia - the traffic department) sends out traffic cops on bike or car to each intersection. These cops are equipped with one whistle each and some of them have white gloves to go with their uniform...
They set up shop in the middle of the intersection and - ignoring the traffic light - they start to increase throughput on the "big artery". Or they try to. Not all of them know their job so well. The best ones increase the number of cars that are able to pass the "light" in a certain timespan by...
- Adjusting the "phases" to the actual demand from the directions, where a "dumb" light would give equal time to all. A feedback loop could do this job too, I presume.
- Giving irregular traffic (that one guy who wants to turn left) an extra slot.
- Most of the time their recipe for success is to lengthen the "packet size", giving each side a longer "phase" to pass through. Since the time one side needs to stop down and another side needs to start moving (when sides change) can be thought of as "overhead", this increases throughput by sometimes going up with the latency too.
- Ideally they prioritize some traffic (the big road) until the "uplink" (the next intersection) is saturated.
So much for the good guy and the theory. There are some cops which had obviously good training and they get lots of experience too. But not all of them are that good, and not all of these measures can be handled by a lone ranger busy with Greece's chaotic drivers. It has happened to me that I had to wait 15 minutes to cross the street as a pedestrian, because the traffic cops tend to ignore pedestrians completely. Lots of drivers sigh (and complain) too, when they see a τροχονόμος (trohonomos - traffic cop) at the intersection.
The concept of adjusting the "traffic shaping" at certain times of day or under certain conditions is good. As a technology guy I would of course prefer a technological solution. Modern computerized and coordinated traffic lights with feedback loops could do the trick. The μπάτσοι (batzi - cops) themselves could be free to do other duties like ticketing speedsters or helping old ladies to cross the street.