Comments on: Traffic Lights

By: Fizanic

Fizanic — Mon, 02 Jun 2008 11:11:44 +0000

You can tell when the sensors are in the road because there’s a rectangle cutout near the light that is the sensor. It’s usually a pressure sensor so when your car rolls on top it will activate. You can usually notice the tar around the edge of the sensor’s rectangle cutout. The cool thing is if you roll over the edge with your bike you can alert the light that you’re there and not have to wait for a car. At least, I think I’m triggering the light.

Also, from what I understand the “push to walk” button at intersections isn’t designed to trigger the light any sooner but add time to the next cycle to allow pedestrians to cross.

By: freakgirl

freakgirl — Fri, 30 May 2008 01:17:01 +0000

Interesting stuff - I had no idea about any of this!

By: Chips O'Toole

Chips O'Toole — Fri, 30 May 2008 01:08:00 +0000

Red light cameras are positioned a ways back from the lights at th e intersections. there are lots here.

That little camera type thingy on top of the lights is a strobe receptor. When emergency vehicles run with their lights on, they also have a strobe, which phases the lights in the direction of travel, so they have to cross fewer busy intersections against red lights.

Once, I was at a light, and in the northbound lane was an ambulance, lights off, but strobe on, waiting for the left turn signal, which never happened, because the light was convinced that the ambulance was trying to get through. we all waited there for minutes before the knob figured it out and turned it off.

incidentally, it’s illegal, but some people have been know to buy strobes to put in the front of their cars in order to get lights to change to a more favorable phase.

I know way too much about traffic engineering, I think.

By: GeekBoy

GeekBoy — Thu, 29 May 2008 20:42:13 +0000

Larrygrrl, I hate to tell you, but I’m pretty sure those are cameras — but they’re designed to record people who run red lights, not people who make wardrobe changes.

By: Larrygrrl

Larrygrrl — Thu, 29 May 2008 20:20:41 +0000

We have a new traffic light here in Bloomsbury, and it has sensor cameras mounted to the overhead arm that holds the traffic light. I hope it’s just a sensor and not a real camera, because I’ve had to make last minute wardrobe adjustments in the car while waiting for that light to turn!

Now that I think of it…it’s the ONLY traffic light in Bloomsbury.

By: Janet

Janet — Thu, 29 May 2008 18:14:51 +0000

You need a sensor for the sensors!

By: anna kathryn

anna kathryn — Thu, 29 May 2008 17:30:41 +0000

There is a push for walk button near my house in Boston that I KNOW does not work. I have literally never seen the walk signal come as a result of pushing that button. It just appears every so often. So you basically just have to dodge traffic.
Then there’s one that does actually work and I can’t resist pushing it several times in a row to make sure it gets the message.

By: GeekBoy

GeekBoy — Thu, 29 May 2008 16:22:10 +0000

I know, right?

By: Hugh

Hugh — Thu, 29 May 2008 16:20:23 +0000

…yet I can NOT resist pushing those stupid “Push for walk” buttons.

By: Chips O'Toole

Chips O'Toole — Thu, 29 May 2008 13:39:13 +0000

I used to do some flagging for the city crew in my howntown that installed these sensors. They do exist. They are basically a loop of metal that read a magnetic current (or create one, or something) when a big chunk of metal is above or around it. That’s why motorcycles usually have to wait, as they don’t trip it. To see if they are there, look at the asphalt. if there is a cutout in the shape of a rectangle, covered by black goo, it’s there. otherwise, nada.

I have recently read that although many NYC traffic lights have “push for walk sign” buttons, only 25% of them actually work. And Otis elevator said in the New Yorker a few weeks ago that the close door button on their elevators is basically not connected to anything, andhasn’t been for years. (I know that Kone elevators are, however)