Local Interest
10:57 am
Sun January 21, 2007

Wilmington's Changing Signal System

Wilmington, NC – Wilmington's Traffic Control Center comes equipped with banks of monitors and walls of maps. But it's not exactly the high-tech hub the nerve-center-esque name suggests. There are water stains along the ceiling tiles, and an old dot-matrix printer in one corner.

I'll use an analogy of how many people still use a DOS computer... Our computers were installed in 1995. At the time we still used DOS software to control signals.

That's Wilmington's traffic engineer, Don Bennett. For the past seven years, he's been the man in the control seat for the city's signal lights. His eight-person crew goes over the system constantly - checking in on control boxes that must endure everything from lightening storms to 130-degree temperatures.

We're also cleaning the cabinets, fire ants like cabinets, signal cabinets, for some reason. So we're de-anting them.

But arthropod infestations are the least of the signal system's problems. Wilmington last integrated all its traffic lights into one system more than a decade ago, leaving more recent corridors, like Military Cut-Off, out of luck. Now the city is in the very early stages of upgrading the whole network: pulling in all the new signals, and improving the communications network.

Imagine your home toolkit to maintain your home. Maybe you've got a hammer, saw, pair of pliers, flashlight, and a couple screwdrivers. So there's a limited amount of repairs you can do to your home. What the newer technology does is gives us more tools.

Chief among those tools is increased memory, which will allow Bennett to program many, many more timing routines for each particular light. Currently there's only room for six at a time, which can be a problem when the department tries to meet real world demands, such as different traffic patterns on weekdays and weekends.

We also have a plan downtown. It's one that we use once a year for about an hour, it's our July 4th evacuation plan.

That plan, with 65 intersections involved, currently takes Bennett a week to program into the computers. The new system will have enough memory to hold 64 routines for each light.


With 64 timing plans, I can not only have a July 4th, I can have a July 4th falls on Monday, Wednesday, Friday. I can have July 4th falls on Friday, Saturday, Sunday.

But while the system upgrade is still more than five years away, Wilmington's traffic lights are constantly changing, and not just in the obvious way. Bennett's office re-analyzes every major artery ever 18 months, trading seconds here and there to massage the flow of traffic.

The city has also started to install use the federal government's newest traffic signal: a flashing yellow arrow to indicate a left turn with yield, which Bennett describes as a great improvement over the usual green circle.

Because it's a different indication: it's yellow, it's not green; it's an arrow, so that it implies therefore it only applies to the turning movement; and because it is flashing, it draws people's attention to it a little better.

Waiting to turn onto Holly Tree from South College, one driver says she was a bit confused the first time she faced the flashing yellow arrow, but not too much.

I thought it was odd, but it worked, I paid attention to it, I did what it said.

Even as new lights and new technology increase the traffic engineer's toolbox, Bennett is quick to point out there's only so much his lights can do to keep the roads moving. Some days, Bennett says, his biggest triumph is just to get one more car through College and Oleander.

With so much congestion on the roads, Wilmington's traffic engineer has to take all the victories he can get.