Traffic light control box question

[Chris142]

There is a 3 way intersection not too far from me.

Friday night some brain dead person crashed there. They completely removed a metal box that was on the corner. I assume that box controles the lights as they are all off now.
The box is about 6ft tall, 4 ft wide and 2ft deep.


The box was on a cement foundation.

Now all thats left is the foundation with a large wire harness sticking up out of the foundation.


The harness looks to be as big around as my leg. ( scary thought I know) Has hundreds if not 1000s of wires.

How would someone repair that? How would they determine which wire does what? Where it goes etc


I know how to use an ohm meter but this looks to be beyond that. You would need a lot of wire off your ohm meter strung across the street to find the other end of the
wire.

 

[JohnnyG]

Oh man, sorry to hear that. We have one not too far from my house like that. Took about 6 months for them to fix it.
They also had to move the flower bouquets to get to it.

 

[bullwinkle]

There should be prints/wiring diagram somewhere showing where everything goes to put the controller back-bet you'll be looking at a 3-way stop for a while!

 

[grasscutter]

Three way intersection you say? We have a couple of those in town.

If there are no cars coming from the perpendicular direction, what's the point in stopping?

And if I need to make a left turn when there's no on coming traffic, I make the left turn.

Why wait at the left turn signal and make people stop at the two-way light when you can safely make your turn if there's nobody there?

 

[Bailey28]

Traffic light control boxes often get taken out due to crashes. Traffic engineering will come out after a crash and fix enough to get the light online with the next light down the road.

Most of these lights are wired to work together and also be controlled from a remote location in the traffic management office.

Most intersections with traffic lights have the capability to monitor real time the traffic volume and backups where the techs can adjust signal duration to help alleviate delays. Some of the traffic management facilities also can intentionally record each intersection as well, depends upon the municipality and or where the intersection is located. Very busy intersections tend to have recording in progress around peak times if not all of the time.

These recordings would not be for running license plates like Flock does but for overall vehicle and pedestrian activity where it records everything in real time.

At this point most city buses also have multiple cameras on each bus which record traffic around the bus in real time. If you have a crash with or near a transit bus ask if you can get a copy of the video to help you in this situation if you don't already have a dashcam yourself.

 

[mk378]

There is usually a wiring vault under the sidewalk near the box. If the box gets clobbered, new wires can be spliced in the vault without needing to run them all the way back to the lights.

New system is a flashing yellow arrow when the straight thru road is green on the other side. If no one is coming the other way, it's legal to turn left on the flashing yellow arrow without stopping. This is made possible with new LED systems can show either round or arrow in the same "eye."

 

[MNgopher]

Lots of backup documentation helps. We've got the design plans for all of ours, as builts of anything that varied from the design, pictures taken at regular intervals, and logs of any logic changes...

 

[Chris142]

Most of these lights are wired to work together and also be controlled from a remote location in the traffic management office.

Most intersections with traffic lights have the capability to monitor real time the traffic volume and backups where the techs can adjust signal duration to help alleviate delays. Some of the traffic management facilities also can intentionally record each intersection as well, depends upon the municipality and or where the intersection is located. Very busy intersections tend to have recording in progress around peak times if not all of the time.

There's an intersection near the fwy thats a real disaster. Caltrans runs the light by the fwy. The city runs the next set of lights 1/2 block away and the lights are not timed to work together.

Place is a real mess.


This is the intersection where the box got destroyed. There is a service truck in the pic. There is a house that got ran into almost monthly. Its where the road dead ends and if cars dont know to go left or right they crash. They built a wall but it got knocked down a few times. Now they put big pipes sticking out of the ground. Seems to have kept cars out of their backyard.

Edit: found an updated pic.

 

[SC Maintenance]

There will be a schematic somewhere. Depends on how old / new on how long to get a replacement.

For those that work on this stuff, I read somewhere that really old stuff was still running on some controller based on OS2. Any truth in this?

 

[Chris142]

There will be a schematic somewhere. Depends on how old / new on how long to get a replacement.

How would a schematic help when there's so many wires and many the same colors?

 

[Propflux01]

Numbers on the wires.

 

[spasm3]

Love to see a pic of that wiring mess!

 

[SC Maintenance]

How would a schematic help when there's so many wires and many the same colors?

It really depends.

They may be bundled. Like 25 conductors in a bundle, all different colors, 10 bundles. You only need to ID each bundle.

Twisted pair. The orange / green twisted pair is easy to identify from the orange blue twisted pair and the blue green twisted pair.

AWG. 14 AWG green not the same as 18 AWG green.

If its truly duplicated you need to either ohm it out - or likely have someone put power on one end and look for it on the other, or if its in conduit likely easier to just pull new wire.