when the stoplight isn't functioning

[HappyRider]

And now for something completely different

https://www.city-data.com/forum/auto...-wait-red.html

[Troubleshooter]

Originally Posted by Labonte18

Here's the issue I have with it.. Now, I always treat it as a 4 way stop.. But who's bright idea was it to program two of the lights to blink red and the other two to blink yellow as a default strategy?

Why not set the default fail action to be all lights flash red?

That is the normal setting for at night when there is not enough traffic to warrant the light. Many signals switch to flashing at night. The street with more traffic gets the yellows and does not have to stop. Some lights are set for a 4-way stop when flashing. It depends on the traffic expected at that intersection.

A traffic light that detects a fault in its controller will also switch to flashing.

When a traffic light starts up after a power failure, it usually goes to flashing for 5 minutes before starting stop-and-go operation.

Many signals with LED lanterns in the signals can keep operating on battery backup for several hours during a power failure.

The biggest problem is a total outage when the signal heads are painted black. Nobody can even see the signals.

[Troubleshooter]

Originally Posted by Lillie767

There are different ways in which a traffic light can be broken.

1. No lights at all means a four-way stop. It's obviously broken.

2. All ways flashing yellow. You don't necessarily know that the light is broken because you can't tell what cross traffic sees. You see a flashing yellow so you proceed as though that's correct. Unfortunately, cross traffic also sees flashing yellow and continues without stopping either. Could be major disaster.

A broken traffic light is not always detectable whilst driving.

A signal should never flash yellow all the way around. Many are set to flash yellow for the main road and red for the side road.

There are many failure cases:

- All signals are out - legally is a 4-way stop in most states.

- Some signals work, others are out - caution if you have a green; stop if you have no indication.
I have seen this when a truck completely knocked a mast arm down.

- One color for one street is out - by watching the signal, you can usually figure out which is out.

- The signal never turns green for your direction - in my state, if you are held for 10 minutes without a green, you can move on red when the way is clear.

- Multiple colors are lit at the same time - severe damage - stop and proceed when safe.