Traffic Light Tutorial

Judging by the way people behave when they get to a traffic light, it may be time for a short tutorial. 

First, there are two basic types of traffic light. There is the timed light and the “On Demand.” Of course, there are numerous derivatives. 

The timed light just has a set time it goes by for each direction. These are usually at major intersections that have a lot of traffic both ways. In Austin, one such is at Lamar and Rundberg. So, the green light may last for 30 seconds each way, or may be 30 for the bigger of the two, and then 20 for the other. Have you ever seen a black hose stretched across the road? It is recording traffic and one of the things it's used for is to decide light timing (among other reasons). 

The On Demand light is a little trickier. It is based on if/when you get to the light. First though some terms. 

Most intersections have a thick white line painted across each of the lanes. I was taught that this line is called the “Threshold.” Recently I’ve learned that it is sometimes called a “Stop line.” I prefer Threshold. It demarcates where you are supposed to stop. Always get as close to it as possible, but don’t go over. I’ll get to that next. 

The Treadle

Buried under each lane at the intersection is what is called the “treadle.” Sometimes you can tell where it is because there are very thin cut lines in the pavement showing where it is buried. It is buried from the threshold to about 10 feet back. So,when you run over the threshold it lets the light know you are there. The On Demand light will soon change when you run over that treadle. 

This is why you must pull up to the threshold. If you don't and it's an On Demand light, you may be there for some time. I've seen this many times. A guy comes to the intersection at a left turn light, but is too far away from the threshold. Typically, the person gets mad because the light won’t change and so runs the light. 

Displaced threshold

Before I mention derivatives of the two lights, let me tell you why you see offset thresholds. This is a threshold that is typically in the left lane and it's set further back from the lane that goes straight. It is painted like this to accommodate turning traffic—especially buses and trucks. If you stop past the threshold it will make it very difficult for those vehicles to turn. It could also lead to your vehicle getting hit. So stop at the threshold/stop line.

A very common derivative of the above traffic lights is a “timed & On Demand” light. It is basically an On Demand light, but it will stay green on a timed sequence. So if you roll up to it, the light will change but stay green for only a short time. Sometimes the time gets extended if multiple cars run across the treadle. In other words, the light is informed that there is more traffic and so it should stay on longer.

We see this light most often at a major street that has a side street that intersects. The light will stay green for the main street and only change if someone pulls up across the treadle on the side street. Often it can take a while for the side street to change even if you have crossed the treadle because the major traffic flow has priority. 

Within the past few years, cities have begun to use a traffic light system that uses a camera to decide if it’s time to change. My experience with these is that it seems less reliable. I’m not sure if it’s because the camera is aimed wrong, has too narrow of a target field or if the software running it is sketchy. Or maybe I’m just going to the wrong intersections. Anyway, this seems to be the future.

So the bottom line of all of this is to be sure and pull up to the threshold/stop line. Then, cross your fingers that it’s not too long of a wait for the light to change.

Ahhh, James Thurber

For this tutorial, I didn't do extensive research, I just knew a lot of it because of my upbringing. My Dad was the City Engineer of a number of cities and so he would often impart knowledge about such things as we drove along. In other words, when other kids riding along with their Dad would get to stop someplace and get an ice cream cone, we would stop at a sewage treatment plant and go look around. Of course, this was years ago so I'm sure that some of the tutorial information has been changed or improved, but for the most part, from current observation, most of it is still present at today's traffic lights. We at The Thurber Brigade hope you enjoyed this little side step and rest assured, we'll get back to blogs about things like relationships, male/female behavior, politics, etc. real soon. Maybe. 

 

 

The Nail in the Road Theory

Only a few short months ago I learned I had a slow leak in one of my car's tires. I used the usual tire fix in a can, but it only held a few days. When I took it in to have the tire fixed ($10) we discovered there was a nail in the tread.

In the old days, I would have ranted about drug addled, crazy teenagers driving around and throwing out nails and screws—along with empty beer bottles. However, except for the last item, I have come to realize they are not to blame.

It's carpenters, construction workers, handymen, etc.

Here's how all those screws, nails and bolts end up in the street—and eventually in our tires. All those handymen and such drive around in pickup trucks, both for the job and to impress the females. Most Don’t drive the high-end trucks with all the fancy accouterments. They drive old beaters with dents, cracks and chipped paint. 

So, at the end of the day, they don't have an expensive, lockable storage compartment in which to throw their tools and equipment. They just toss the stuff into the bed and drive on.  This includes boxes of nails and screws. 

These boxes are probably closed and lain next to the man's other gear with little thought about repercussions and consequences. So, as he's driving along he hits a pothole. Everything in the bed raises an inch in the air and lands back down in it’s previous spot with nothing more than a loud bang. However, the lid of the nail box has loosened. 

On the next bump, the lid flies open. The next bump sees one or two nails fly out onto the bed. Then driving over rough pavement, not even a pothole, the vibration carries the nails down the length of the bed. They will then find a hole in the bed, either a natural one designed to let water out, or one from rust and wear. If there are no holes, the nails make it down to the end of the bed to the tailgate.  Normally, they’d be stopped by it, but it's an old truck and the fit isn’t as tight as in the early years.

In the end, the nails, screws or whatever find their way out of an opening and down onto the street. Just waiting for the next driver to come along and pick them up. In their tires.

And so that is the way all those nails, tacks, screws and whatever find their way onto our roads. Not because of some crazed youth out for a night of adventure. No, they are there thanks to that handyman you hired to fix some problem in your home. 

Remember this the next time you pass one of those old pickups. Be sure and shake your fist and cuss them out for all the mayhem (and cost) they've brought to your life. I'm sure they'll understand.

My Dad warning me not to ever put nails in the back of my Datsun pickup.