Why our outdated traffic signal ‘system’ is a failure

Traffic signalization is a science in itself. With the tremendous advancements in electronics and digital technology in the last 20-plus years, many of those innovative technologies have been directly applied to traffic signal technology all around the entire world. That is, except here on Kauai where so much of the financial resources for “transportation” are used instead for bicycle lanes that are rarely used, except for infrequent “recreation.”

How many times have you sat waiting to turn left out of the Foodland or Safeway parking lots and wondering why the green light doesn’t go on for you and there’s no traffic going through the green light on Kuhio Highway? OK, maybe that’s not a very good example because there’s almost always traffic on Kuhio Highway. But you know what I mean. You’ve seen it in many places.

Or how about a left turn arrow opposing your direction and there’s no vehicle turning left there. And yet, for no good reason, except that you’re a good law-abiding driver, you sit there and wait for what seems to be an eternity. And it may be you and another 50 vehicles behind you.

There are two reasons for the failure of our traffic signal system.

The first reason is that it isn’t a “system” at all. A “system” is defined as “a group of related parts that move or work together.”

None of our signals “work together” because they are not interconnected in any way.

Although technology has likely changed in the last 15 years, an “interconnect” is a hard-wired connection between signalized intersections by way of a conduit that runs from one intersection to the next. This allows the signal controllers to interact with each other and provide some synchronization designed to keep traffic flowing, minimizing stop and go, which, besides preventing a bottleneck, considerably reduces vehicle emissions.

While the signals on Nawiliwili Road, fronting the Kukui Grove Shopping Center, were being installed, I stopped and asked a worker if they were installing an interconnect system. His response to me, with a laugh, was, “No, not on this one.”

The second reason for the failure of our traffic signals is the inefficiencies and/or lack of proper detection.

While some intersections appear to include some sort of detection equipment, it is obvious that in most cases it simply does not work or is just improperly calibrated and/or maintained.

Detection is usually in the form of induction loops embedded in the pavement to detect the presence of vehicles.

While they seem to be present at some intersections, it is obvious to me that they are not working properly. Most likely because the pavement in which they are embedded is so broken up, the loops are likely damaged.

The state has gone to other means of detection but they are not adequate nor effective to the current traffic situation on Kauai. They may have been 20-30 years ago when the number of vehicles on Kauai was less than half of what it is today.

Advanced detection is detection that is set in the pavement a few hundred feet before a signalized intersection and is connected to the controller for that intersection. It detects the presence of vehicles, and even the volume and speed of vehicles that are approaching the intersection.

But more importantly, it also detects the absence of vehicles. This information cues the controller/computer to either skip or minimize the green time for that phase of the cycle.

The lack of advanced detection is the reason you sit and wait at a red light even when there is no traffic utilizing the green time in the other direction.

Perhaps, if the county could work with the state engineers to get our traffic signals upgraded to current standards and working properly, there’s a good chance that there could be some improvement in the traffic flow in many locations around Kauai.

w Online: https://tn.gov/assets/entities/tdot/attachments/TDOT_Traffic_Design_Manual_Chapter_08_Dec2016.pdf


Larry Arruda is a resident of Kapaa.


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