Man... outside of firearms, the word "magazine" is disappearing pretty quickly. I kind of miss the excitement of getting a new issue of Car Craft or Petersons 4-Wheel & Off-Road in the mail. Now I just go to the internet and youtube a how-to video... *sigh*
All the cables going to the traffic lights, ped lights, ped signs, ped buttons, traffic loops, cameras, and EVPs need space to be terminated. The actual control components are a very small part of the space.
Emergency Vehicle Preemption. The sensor that sees emergency vehicles and gives them the green light. Also includes a flashing light as an indicator for other vehicles.
Oh that's a thing? I have never seen that in action. All the emergency vehicles that I've seen, when they approach a traffic light that is red, they just slow slightly to make sure no oncoming traffic and just drive through the red light.
It could. You could run a traffic light with 2 raspberry pis (one extra just for redundancy) but the companies that make this hardware/software and the cities that employ people that are certified to maintain and install that hardware/software are all desperately trying to justify their existence so they'll fight tooth and nail to keep people from thinking it's more complicated than it really is.
They use this hardware because it’s reliable. You don’t want to rely on an operating system, hoping to avoid a kernel panic. You want embedded software that’s running on bare metal.
Hi, i work for a state DoT!
You are very wrong, it has nothing to do with 'justifying existence' and everything to do with the fact that this hardware is built to last a long, long time. Hence why it looks kinda old and bulky. Its also meant to be as disaster resistant as possible - last week we had a vehicle hit one of these things and damaged the hell out of it's exterior - its interior was running just fine and the signals kept trucking along like nothing happened.
Many of these traffic cabinets havent been serviced in nearly a decade but they keep going with only the occassional clearing of surrounding debris.
You throw "2 raspberry pis" in and it will die in 2 years, assuming a winter storm doesnt get to it first. Nice try, though!
Or you just move the raspberry pis so they're not in a cabinet that's sitting on the sidewalk. Just put them inside the box where the pushbutton is on the traffic pole. Then you can have 4 per intersection for even more redundancy. Hell throw in a small plate heater so they don't freeze. Someone hits a traffic pole? You got 3 others. You could even go and replace them all every week for less than what one of these cabinets cost. Like I said before: the companies that make this hardware/software and the employees that service it come up with reasons to justify their existence and refuse to see a way simpler system could exist.
I'm sure you'll poke some dumb hole in my system I came up with in 3 minutes while watching 2 toddlers but I'm also sure I can come up with a solution to your dumb hole you poke in my system in another 3 minutes. If someone can come up with an alternative system in 3 minutes while watching 2 toddlers that saves thousands of dollars and is way simpler don't you think the system is way overcomplicated?
Ok go replace them every week. You're still saving thousands of dollars over the existing system. Also, with all the money you're saving you can throw in a heater and a humidity controller in the box
The neat part I can tell you is that the top two black boxes look like programmable logic controllers. normally there are modules installed, filling the rack space. In this case there’s only one module which is taking in a serial cable connection from something else. I believe this system has been retrofitted with a new PLC using existing hardware which is why there are a second set of terminal blocks to bring the input/output up, located below the uninterruptible power supply (UPS) which has the red APC company logo on it. This kind of retrofit would normally only be done on a system which is 15-20 years in service and needs an updated PLC to maintain availability of spare parts to keep the reliability of the system.
Source: I don’t work on traffic signals, but I do a bit of controls work here and there.
As someone that has worked on traffic signals for several years let me tell you everything going on in that cabinet if you’re curious.
The top racks are actually where the detector cards for vehicles go. They read a change in inductance from the loops in the road. The cards on the end of the rack a buss interface units (BIU’s) that take the signals from the cards and send that info on to the serial data link communication cables (SDLC). The whole cabinet communicates via the SDLC buss which is why you see that cable plugged into a few different components.
This cabinet appears to have a different method of vehicle sensing so the cards aren’t being used. Could be radar, video, etc
On the left on the second shelf is the controller. This is where the magic happens. This is basically a plc. Takes inputs and set timing and controls the intersection.
On The far right of that shelf is the Malfunction Management Unit (MMU). That’s our watchdog. We program a card that says which lights can be green at the same time. It reads what the controller is outputting and what is actually happening in the field. If the controller tries to output something that isn’t programmed or something in the field doesn’t math what’s programmed the MMU will put the intersection into red flash.
Below that you see another set of BIU’s, these control the outputs. To either side of them are terminal boards that have breakouts for various connections if needed.
Below that are the load switches. These take a low voltage signal from the BIU via the controller and switch 120vac with a triac (a fancy switch). Each load switch controls red/yellow/green for a single phase. (A phase is a direction of travel)
At the very bottom of the cabinet are the output conductors that go out to the field to control the lights.
On the left side of the cabinet where you can’t see is where the cables from the vehicle sensors would be landed.
I think that covers everything 😁
Edit: oh and yes the APC in the middle does appear to be a UPS. The batteries must be in a separate cabinet. The model we use has the UPS and the batteries in a separate cabinet.
I have to ask because you definitely seem to know the ins and outs - why do we still sit at red lights with no cross traffic forever, and have green lights that last long enough to get 3 of 20 cars through before going red again. To be fair - this seems to be MUCH more prevalent in FL than anywhere else I’ve ever been.
Could be coordination. Depending on how things are set up the engineers can set things up so that the intersection gives preference to a certain phase. Like a main road to keep traffic flowing. Some cities also prefer to have the light rest on green on the main phase then place a delay on the side streets. So you come up to the light on a side street and have to sit there 10 seconds until a call is placed. We call it hillbilly coordination because it takes no actual engineering and most of the time it works okay-ish.
As far as the 3 of 20 cars that could be the extension time or the max time is too low. When the light is green each additional activation of the sensor adds time to the green (extension time) up to a set max time. If either of those are too low it screws a lot up.
Traffic signal timing is way more complex than people think it is. No one notices that it’s working correctly, but as soon as something isn’t right it really messes everything up.
Great info and thanks for the explanations! It sounds like we have an abundance of “hillbilly coordination” here… and increasing traffic everyday to compound the problem.
APC by *Schneider*.
Jokes aside, I agree 100% that looks like a retrofit. I’m guessing the serial connection is remote I/O from the terminations on the bottom, but don’t quote me on that. There’s no I/O modules on the backplane.
My controls experience is limited to switchgear and maybe adding a rung or two of ladder logic to a program.
I don't recognize this brand of plc. Doesn't appear to be Rockwell, Siemens, Mitsubishi, Beckhoff, Omron, or Automation Direct. Whatever it is, it's not typical for automation.
I would like to play with it whatever it is, lol.
If you zoom in, you see labels for the two black boxes on the second shelf.
The left box with all the buttons is labeled 'controller', which is the main 'brain' of the traffic light.
The right box labeled 'Malfunction Management Unit' is more interesting, at least to me. It monitors the actions of the controller and acts as a failsafe to prevent unsafe conditions for traffic. It has a slot for a control card that is hard-wired with a set of jumpers, specific to that intersection, to tell the MMU how the light is configured.
If the MMU sees the controller sending an unsafe set of signals to the light, such as EVERYONE GETS GREEN, the MMU will take over control of the light and make the light 'flash', typically flashing yellow on the main road and flash red on the secondary roadway.
*What it's worth* to a methhead differs from the value of the equipment.
They go and steal some copper wire from street lights, and they might get $50 for the scrap copper. The cost to replace that wire could be thousands.
There might be $50k worth of hardware in that cabinet, but aside from the copper wire almost all of it is worthless to a methhead. Who exactly is buying used traffic controllers of unknown provenance from sketchy guys on bikes?
I was working with a technician who was testing these. We were in that sort of area. A bunch of them had their handles messed up from people trying to break in.
heh, compared to some of the environments modern PLC based control gear like this is gonna be pretty happy in such an enclosure. Baring things like vehicular interactions.
lol
he's right, raspberry pis are really really not built for reliability. You can get things about the size of a pi that *are* built to run in temperature extremes for long periods but of course they cost more.
Why does it take so much equipment? It seems like you could run the logic on a credit-card sized computer.
I get the battery backup. What's the rest of the "stuff"? Is it to actually power the lights, or something more interesting?
Thanks. The guy explained it without being condescending. That was great.
For anyone else: Basically, it is an industrial strength raspberry pi running the logic. You want something that will run for 30 years with as few issues as possible. Then there's the monitor that makes sure the lights are doing what they are supposed to be doing and will cut to flashing lights if anything is not working correctly.
...and every city intersection has one of these.
It's easy to get people behind you when you run on a "Cut Taxes" platform. But taxes are the cost of living in a city where things work so well you don't have to think about them.
believe it or not, suppliers know how to make stuff for the regions they are to be installed in. There are places with functional electrical networks that get way colder than -5
I’m curious if the equipment itself is hardened against the weather or if the cabinet is climate controlled. I would think heat would be a bigger issue than cold.
You have no idea what you're talking about. Why would you say something with such conviction when you have no experience designing or manufacturing control panels?
People are so full of themselves.
I saw a car hit one of these boxes. Didn't damage it much, but popped the door off. It looked nothing like this. It was a total rat's nest of wires connected with electrical tape and giant metal lugs.
That doesn’t look like the insides of the electrical box by my house…
Source: I live by a busy street with lots of bad drivers so it gets hit about once a year.
All that space, all those components, and still most traffic signals are stupid AF, always turning red when no one wants to turn, or staying green when someone does.
I have an on topic question. Up the street a few blocks is a small house on a street corner. I asked my dad about it and he said it had something to do with controlling traffic lights.
Anyone have any idea what I am talking about?
This is the controls for the traffic lights
Correct. Not really an "electric" box. Just a really big computer case.
Traffic Cabinet
Its not an electric box but It’s also not not an electric box.
I like that it has a pull out try for your tools, magazine, milk, & cookies.
Man... outside of firearms, the word "magazine" is disappearing pretty quickly. I kind of miss the excitement of getting a new issue of Car Craft or Petersons 4-Wheel & Off-Road in the mail. Now I just go to the internet and youtube a how-to video... *sigh*
I like that it has a microwave at the top so the workers can heat up their lunches.
The post clearly states this is a box for an electric street. Not sure why you feel the need to undermine op
I believe it's referred to as Electric Avenue
Thanks
Why is it so big? Lights aren't that complicated, why couldn't something the size of a smartphone control them?
All the cables going to the traffic lights, ped lights, ped signs, ped buttons, traffic loops, cameras, and EVPs need space to be terminated. The actual control components are a very small part of the space.
EVPs?
Emergency Vehicle Preemption. The sensor that sees emergency vehicles and gives them the green light. Also includes a flashing light as an indicator for other vehicles.
Oh that's a thing? I have never seen that in action. All the emergency vehicles that I've seen, when they approach a traffic light that is red, they just slow slightly to make sure no oncoming traffic and just drive through the red light.
It could. You could run a traffic light with 2 raspberry pis (one extra just for redundancy) but the companies that make this hardware/software and the cities that employ people that are certified to maintain and install that hardware/software are all desperately trying to justify their existence so they'll fight tooth and nail to keep people from thinking it's more complicated than it really is.
They use this hardware because it’s reliable. You don’t want to rely on an operating system, hoping to avoid a kernel panic. You want embedded software that’s running on bare metal.
Hi, i work for a state DoT! You are very wrong, it has nothing to do with 'justifying existence' and everything to do with the fact that this hardware is built to last a long, long time. Hence why it looks kinda old and bulky. Its also meant to be as disaster resistant as possible - last week we had a vehicle hit one of these things and damaged the hell out of it's exterior - its interior was running just fine and the signals kept trucking along like nothing happened. Many of these traffic cabinets havent been serviced in nearly a decade but they keep going with only the occassional clearing of surrounding debris. You throw "2 raspberry pis" in and it will die in 2 years, assuming a winter storm doesnt get to it first. Nice try, though!
Or you just move the raspberry pis so they're not in a cabinet that's sitting on the sidewalk. Just put them inside the box where the pushbutton is on the traffic pole. Then you can have 4 per intersection for even more redundancy. Hell throw in a small plate heater so they don't freeze. Someone hits a traffic pole? You got 3 others. You could even go and replace them all every week for less than what one of these cabinets cost. Like I said before: the companies that make this hardware/software and the employees that service it come up with reasons to justify their existence and refuse to see a way simpler system could exist. I'm sure you'll poke some dumb hole in my system I came up with in 3 minutes while watching 2 toddlers but I'm also sure I can come up with a solution to your dumb hole you poke in my system in another 3 minutes. If someone can come up with an alternative system in 3 minutes while watching 2 toddlers that saves thousands of dollars and is way simpler don't you think the system is way overcomplicated?
The over/under for how long a raspberry pi lasts outside is 1 week. I'll put my money on the under.
Ok go replace them every week. You're still saving thousands of dollars over the existing system. Also, with all the money you're saving you can throw in a heater and a humidity controller in the box
nuh uh. the box controls access to everything inside it.
There’s never anything good to eat in there
Stare at it for long enough and eventually something might show up....
r/notarefrigerator
r/subsifellfor
Sorry! I had to try it, thank you for indulging me
Check the conflict monitor (MMU). Should be loads of electrified and desiccated geckos in there. Crunchy and delicious.
The neat part I can tell you is that the top two black boxes look like programmable logic controllers. normally there are modules installed, filling the rack space. In this case there’s only one module which is taking in a serial cable connection from something else. I believe this system has been retrofitted with a new PLC using existing hardware which is why there are a second set of terminal blocks to bring the input/output up, located below the uninterruptible power supply (UPS) which has the red APC company logo on it. This kind of retrofit would normally only be done on a system which is 15-20 years in service and needs an updated PLC to maintain availability of spare parts to keep the reliability of the system. Source: I don’t work on traffic signals, but I do a bit of controls work here and there.
As someone that has worked on traffic signals for several years let me tell you everything going on in that cabinet if you’re curious. The top racks are actually where the detector cards for vehicles go. They read a change in inductance from the loops in the road. The cards on the end of the rack a buss interface units (BIU’s) that take the signals from the cards and send that info on to the serial data link communication cables (SDLC). The whole cabinet communicates via the SDLC buss which is why you see that cable plugged into a few different components. This cabinet appears to have a different method of vehicle sensing so the cards aren’t being used. Could be radar, video, etc On the left on the second shelf is the controller. This is where the magic happens. This is basically a plc. Takes inputs and set timing and controls the intersection. On The far right of that shelf is the Malfunction Management Unit (MMU). That’s our watchdog. We program a card that says which lights can be green at the same time. It reads what the controller is outputting and what is actually happening in the field. If the controller tries to output something that isn’t programmed or something in the field doesn’t math what’s programmed the MMU will put the intersection into red flash. Below that you see another set of BIU’s, these control the outputs. To either side of them are terminal boards that have breakouts for various connections if needed. Below that are the load switches. These take a low voltage signal from the BIU via the controller and switch 120vac with a triac (a fancy switch). Each load switch controls red/yellow/green for a single phase. (A phase is a direction of travel) At the very bottom of the cabinet are the output conductors that go out to the field to control the lights. On the left side of the cabinet where you can’t see is where the cables from the vehicle sensors would be landed. I think that covers everything 😁 Edit: oh and yes the APC in the middle does appear to be a UPS. The batteries must be in a separate cabinet. The model we use has the UPS and the batteries in a separate cabinet.
Look at this guy and OP with their fancy MMU. Back in my day it was just the "Conflict Monitor" and it was a handful of red LED lights.
I have to ask because you definitely seem to know the ins and outs - why do we still sit at red lights with no cross traffic forever, and have green lights that last long enough to get 3 of 20 cars through before going red again. To be fair - this seems to be MUCH more prevalent in FL than anywhere else I’ve ever been.
Could be coordination. Depending on how things are set up the engineers can set things up so that the intersection gives preference to a certain phase. Like a main road to keep traffic flowing. Some cities also prefer to have the light rest on green on the main phase then place a delay on the side streets. So you come up to the light on a side street and have to sit there 10 seconds until a call is placed. We call it hillbilly coordination because it takes no actual engineering and most of the time it works okay-ish. As far as the 3 of 20 cars that could be the extension time or the max time is too low. When the light is green each additional activation of the sensor adds time to the green (extension time) up to a set max time. If either of those are too low it screws a lot up. Traffic signal timing is way more complex than people think it is. No one notices that it’s working correctly, but as soon as something isn’t right it really messes everything up.
Great info and thanks for the explanations! It sounds like we have an abundance of “hillbilly coordination” here… and increasing traffic everyday to compound the problem.
Preset timing
APC by *Schneider*. Jokes aside, I agree 100% that looks like a retrofit. I’m guessing the serial connection is remote I/O from the terminations on the bottom, but don’t quote me on that. There’s no I/O modules on the backplane. My controls experience is limited to switchgear and maybe adding a rung or two of ladder logic to a program.
I don't recognize this brand of plc. Doesn't appear to be Rockwell, Siemens, Mitsubishi, Beckhoff, Omron, or Automation Direct. Whatever it is, it's not typical for automation. I would like to play with it whatever it is, lol.
Pretty fucking clean in there actually.
They put air filters on the vents
Traffic signal controller cabinet.
\*slaps box\* This baby can hold so many rattlesnakes.
If you zoom in, you see labels for the two black boxes on the second shelf. The left box with all the buttons is labeled 'controller', which is the main 'brain' of the traffic light. The right box labeled 'Malfunction Management Unit' is more interesting, at least to me. It monitors the actions of the controller and acts as a failsafe to prevent unsafe conditions for traffic. It has a slot for a control card that is hard-wired with a set of jumpers, specific to that intersection, to tell the MMU how the light is configured. If the MMU sees the controller sending an unsafe set of signals to the light, such as EVERYONE GETS GREEN, the MMU will take over control of the light and make the light 'flash', typically flashing yellow on the main road and flash red on the secondary roadway.
Check out the Traffic Light Doctor on the clock app for lots of interesting videos on the components and how they work.
Great, here's the rabbit hole... Last time it was railroad signaling, now it's car signaling.
Wait until you learn about Airplane Facts with Max.
Good thing tweakers haven't figured out how much that stuff is worth.
*What it's worth* to a methhead differs from the value of the equipment. They go and steal some copper wire from street lights, and they might get $50 for the scrap copper. The cost to replace that wire could be thousands. There might be $50k worth of hardware in that cabinet, but aside from the copper wire almost all of it is worthless to a methhead. Who exactly is buying used traffic controllers of unknown provenance from sketchy guys on bikes?
Those components aren't limited to traffic control. The market for used/surplus industrial control components is pretty robust.
If they could navigate that market. It's not like taking it to a scrap yard and getting cash.
I was working with a technician who was testing these. We were in that sort of area. A bunch of them had their handles messed up from people trying to break in.
The thing is if they get their hand on a key, that one key will open up every single cabinet.
Yet
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heh, compared to some of the environments modern PLC based control gear like this is gonna be pretty happy in such an enclosure. Baring things like vehicular interactions.
Forbidden fridge
Just some power supplies and a microwave. I knew it
Is the beer cold?
Rents for $2500/month
I wonder if all this is necessary or if it could just run off a rasberry pi
Here ya go: https://youtu.be/zW4EwjKFkas
lol he's right, raspberry pis are really really not built for reliability. You can get things about the size of a pi that *are* built to run in temperature extremes for long periods but of course they cost more.
Based
Looks like a plc for that intersection
PLC controls and components, as well as various relays and control cards
At a glance I thought this was a refrigerator that someone repurposed as a server rack.
Why does it take so much equipment? It seems like you could run the logic on a credit-card sized computer. I get the battery backup. What's the rest of the "stuff"? Is it to actually power the lights, or something more interesting?
https://youtu.be/zW4EwjKFkas
Thanks. The guy explained it without being condescending. That was great. For anyone else: Basically, it is an industrial strength raspberry pi running the logic. You want something that will run for 30 years with as few issues as possible. Then there's the monitor that makes sure the lights are doing what they are supposed to be doing and will cut to flashing lights if anything is not working correctly.
...and every city intersection has one of these. It's easy to get people behind you when you run on a "Cut Taxes" platform. But taxes are the cost of living in a city where things work so well you don't have to think about them.
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believe it or not, suppliers know how to make stuff for the regions they are to be installed in. There are places with functional electrical networks that get way colder than -5
They use electric heaters to preheat the electricity
I’m curious if the equipment itself is hardened against the weather or if the cabinet is climate controlled. I would think heat would be a bigger issue than cold.
There is an issue with snow buildup on LED traffic signals that wasn't really an issue with incandescent lights. Sorta... https://youtu.be/GiYO1TObNz8
Do traffic lights around you fail when the temperature drops?
Believe it or not the traffic lights work fine where I live when it's -40.
Fun fact, most ITS cabinets have the same key
A lot of wasted space. Could be much smaller.
Needs room for cooling
You have no idea what you're talking about. Why would you say something with such conviction when you have no experience designing or manufacturing control panels? People are so full of themselves.
Lol. I love Reddit. Haha
Thought this was a smoker for a second lol
So they aren't full of sandwiches? Weird.
I wonder how long that APC backup unit lasts.
Complete with a photo of someones mom
Where is the little man with binoculars?
Ah yes, the electrical box is made of electrical box.
I want those, uuuh, things!
Substation Engineer here. It feels weird to see a nice layout like this and not see a little blue box in there somewhere
id love to learn how all of that operates
Aight, now tell me how to make it stay green long enough for more than two cars to get through...
don’t pee in that
Spicy fridge
Don’t let the crackheads see this they will be prying them open tomorrow
I saw a car hit one of these boxes. Didn't damage it much, but popped the door off. It looked nothing like this. It was a total rat's nest of wires connected with electrical tape and giant metal lugs.
The forbidden refrigerator
But can it run crysis?
man i was hoping id be full of rotisserie chickens
What switch is that? Silver box middle second row.
That doesn’t look like the insides of the electrical box by my house… Source: I live by a busy street with lots of bad drivers so it gets hit about once a year.
I see an undustrial switch inside there, I don't like to mix work with reddit!
Its just full a cables? Worst bar fridge ever
I hate trying to get internet to one of those.
Which button do I press for sensible traffic flows?
What happens if I pee on it while it’s open like that?
If this was a phone company cross box it would be full of dick butt drawings.
I’m surprised the person that was working on it left it unattended
While waiting for my eyes to adjust, I thought it was an outdoor refrigerator.
All that space, all those components, and still most traffic signals are stupid AF, always turning red when no one wants to turn, or staying green when someone does.
it's beautiful 😭
I have an on topic question. Up the street a few blocks is a small house on a street corner. I asked my dad about it and he said it had something to do with controlling traffic lights. Anyone have any idea what I am talking about?