How can you not know that traffic lights have sensors?

The BBQ Pit
41

There’s a sensor near my girlfriend’s in the city. It routinely malfunctions so people have to get out of their cars and go push to button that activates the pedestrian signal. I’ve seen a bus driver have to do this.

A lot of intersections here seem to be on some kind of combined system: timed during the day or rush hour, or whatever, then in the evenings or overnight they are on sensors.

However the ones that really piss me off, seem to give the right of way to the main street and the light changes back if there is traffic on it. For example, near my mom’s you sit at the light. She lives on a secondary street that crosses a Big street.

You sit and you wait. And wait. Finally the flashing “DON’T WALK” sign comes on to warn Big street pedestrians to hurry up and finish crossing. Hooray, it’s telling you that the light is finally about to change, soon it will be yellow for the Big street and then red, and then you can go! Then suddenly a car comes over the horizon, still two blocks away on the Big street… POOF!.. suddenly the “WALK” signal for the Big street comes back on so that car that was way, way, back doesn’t get the amber after all, doesn’t get the red, and presto, you’re waiting through another cycle.

Rinse. Repeat. Rinse. Repeat.

These ones, I just don’t get. If the light is changing (as evidenced by the flashing “Don’t Walk” sign), then how come any car travelling along that street can change it back to green? If it only happened once, I’d figure some sneaky bastard had a device like what they use in ambulances to override the light, but if you’re waiting at that light by my mom’s late at night, you will see this over and over and over.

I could understand it if the Big street usually had the green and the secondary street had a sensor. That would make sense. The Big street would stay green unless there was a car that needed to cross it. But that isn’t the case at this intersection (and a few other’s in my mom’s town). You wait, the light starts to change for you, and then traffic on the Big street changes it back again, so you never get to go unless there is a HUGE gap in traffic (and even 3am there doesn’t seem to be a gap big enough for that piece of shit.)

WTF?

42

Intersection sensors are of course everywhere in SoCal. They’re easy to see–just look for the loop cut into the pavement (I was going to say “tarmac”, but it’s actually a trademark!). Many intersections will have more than one loop for each lane. One near the stop line that will detect if a car is waiting, and then another one 8-10 car-lengths back to detect if there’s a lot of cars waiting. The light will stay green longer if there’s more cars.

If I’m feeling naughty, I stop on the second sensor to get a longer green (especially important on protected left turns).

43

So uh, am I the only one that thinks these sensors are approximately the dumbest thing ever?

44

But they’re not, really. If sensors are used properly, they can be extremely useful. There are plenty of places in shopping areas in suburbia in which almost no one drives the side streets late at night. Sensors mean that traffic on the main thoroughfare doesn’t have to stop for non-existent traffic on the side street.

On edit: the ad I’m getting is to repair circumcision damage?

45

Probably. I can think of one near where I grew up, where a highway ends at an intersection near the busy part of town. There’s very little traffic that comes off the highway, so the light is usually green for the cross traffic, but there’s a sensor that’ll flip the light if there’s someone waiting.

Other lights in town don’t go to sensors at night though–they switch to flashing red and act the same as a stop sign.

46

I hope so. A smartly programmed light with sensors is almost is a good as a pair of cops directing traffic manually (lights don’t swear at or ticket asshole drivers).

47

May I humbly suggest that the driver may have been renting the car, and was from a part of the world where traffic lights work on timers, not sensors?

48

Swallowed, if that was happening at 3:00 am with no traffic except the very occasional car, maybe you need to make a right and a left at the next corner.

I love the sensored lights late at night. I hate the ones still on timers, as we sit there with our thumbs up our bums for no cross-traffic at all.

49

That’s part of the problem. The next interesction is a looooong ways away and then the next chance to turn so you can start getting back on track is also a loooooon ways away. So what’s been happening is that a nearby residential neighbourhood (that typically has even less traffic than my mom’s street), gets a pantload of traffic in the wee hours, or people make the illegal left, or they turn right and make a u-turn.

I’ve seen some of these light in the outskirts of the city, near the highway, where there is enough traffic to warrant lights, but very few intersections. Following your suggestion (it’s a good suggestion, for residential roads, but…) you’d end up driving miles and miles in the opposite direction, until you had an opporunity to turn around in the parking lot of a factory or the dirt driveway of a farm.

The sesor light swork just fine, these weirdo, Big-road-gets-priority-no-matter-how-many-other-cars-are-waiting camera things drive me bugshit.

I’ve seen them in other towns and they seem to work better, but in my mom’s town they suck goats.

50

So far as I’ve noticed, there is one induction sensor in my neighbourhood. It covers the left half of a double-wide lane, and it’s a great big PITA. For some reason, car drivers at this intersection like to come to a stop as far to the right as they can, so they never trigger the signal.

If I’m lucky, I can pull up directly over the right-hand side of the loop on my motorcycle and get a green light 10 seconds later.

But I’m not surprised most people aren’t aware of them. There was a column in the local weekly rag last week about a guy expressing his surprise at getting a ticket. He’d apparently spent the past SEVEN YEARS wondering why drivers in the two left hand lanes were always crawling along, while he blew past them in the right hand lane. Said dickhead didn’t realize he was going straight in a right-hand turn only lane. He apparently didn’t notice the two signs on posts, the paint on the street, or the green arrows on the lights :smack:

51

My wife (aka the doper Cyn) Was rear ended and pushed 50-60 feet hit by a much larger vehicle that did not apply brakes. She stopped on the far side of the intersection.

52

… I could be wrong, but I don’t believe any of the traffic lights in the New Orleans metro area operate by sensors. Possible exception for the middle of the night in some areas. Hadn’t noticed sensors or heard about sensors in several other cities in Lousiana and Mississippi.

53

Guys, you’re probably just not seeing them, actuated traffic signals are extremely common in almost every city in the US. They’re not a newfangled experimental idea, they’re a basic and essential tool for traffic management that have been used for decades. I know for a fact New Orleans has them. They’re unobtrusive and you really won’t notice them unless you’re specifically looking for them. The camera ones don’t really look like cameras in most cases and can be hard to spot (I even have trouble spotting them sometimes and I’m a traffic engineer) and not all of the induction ones leave markings in the road.

But, I guess the OP’s question has been answered: a surprisingly large number of educated people don’t know much about how traffic signals work.