How do stop lights "see" your car (to turn green)?

[@richardschmidt4627]

Traffic lights see my car and turn RED!!!

[@DayInMontreal]

Thats because the magnetism in your car is negative. Just go see a mechanic.

[@pablocruise678]

Or my city bus here in Vegas

[@justa9uy]

@@DayInMontreal So the answer is to only have positive vibes?

[@chubbyadler3276]

I am starting to think that signals are intentionally designed to do that. I would say it was for ticket revenue, but I am not seeing the officer at his post, nor am I seeing blue lights chasing people I see running it.

[@295g295]

I have seen a light turn green quicker for an ambulance.

[@kayzeaza]

This channel is underrated

[@dasanders13]

I agree president

[@daedalus372]

... George ain’t lying!

[@Lyerbait13]

Understatement

[@winforworkgroups]

Our teachers have been lying to us when they tell us George is dead

[@skLaszlo]

wait guys he's alive still

[@robertmills2900]

Many times in the past when I rode motorcycles, I would have to get off my motorcycle and push the crosswalk button to finally get a green light. 🤣

[@captainkirk8873]

AM TOLD RARE EARTH MAGNETS ATTACHED TO UNDERSIDE OF BIKE WORK ON LOOP SENSORS

[@rogerwilcojr]

"Most" places it's legal for motorcycles to treat red lights that don't change as stop signs.

[@_DMAC]

@@rogerwilcojr try riding an aluminum or worse yet a carbon bicycle. Good luck! Had some local known lights id just treat as a stop unless a motor vehicle was there to trip the light.

[@wanderingjana891]

I've recently not had a left turn light change cycles in a row. Apparently my sub-compact either didn't have enough metal or the camera didn't get it. So weird. I eventually just went when it was clear.

[@PennsylvaniaDualSport]

Putting your stand down should be enough to trip the light

[@lberry750]

As a former traffic homicide investigator, learning about signaling was a big part of my job. My biggest “takeaway “? In left turn lanes, where there is a green turn arrow for protected turns, there are often two loops, one behind the other. If you stop over the loop closest to the intersection, and no one is behind you, you will probably get a solid green light and have to yield to any oncoming traffic. If you stop over the rear loop, the computer sees multiple cars waiting to turn left and will most often give you a green turn arrow…depending on whether or not there are cars opposing you. The trick…always stop over the rear loop for the best chance of a green arrow.

[@thatsounditmakes9177]

As a cyclist, the worst part of triggering signals is standing there, waiting and hoping that the signal will change because whatever tool the signal used to detect you has detected you (especially left turn signals). And after 3 or 4 cycles of cars driving thru and your signal being red the whole time you just give up and run it....and then get pulled over by the cop that was hiding behind a bush expecting you to run that red. 🙄

[@kevincashmore3678]

“That’s forth floor stuff, I took classes down in the basement” best underrated joke ever 😂

[@DeepakKumar-xv5tq]

Where timeline please 🙏

[@HelloKittyFanMan.]

The floor going forward (forth)? I'm not sure I follow you. Are you sure he wasn't saying "fourth" ("4th") instead?

[@DeadlyHellhound]

@@DeepakKumar-xv5tq 5:00

[@geezer652]

"classes down in the basement” sometimes also called "summer school" ;

[@MikeDCWeld]

That's a fourth floor joke. I teach in the basement.

[@cruzuscog]

In my town the traffic lights have the magical ability to turn red while I'm the only one approaching

[@Arat1t1]

Many years ago I was scrolling through random free TV channels and stumbled upon a Chinese show where they would visit countries around the world and see what they could learn. For Sweden the first one was sustainable neighborhoods, and the second one was exactly this. They seemed amazed by how our traffic lights weren't just on a timer, and how they could adapt depending on the traffic flow, the time of day, pedestrian flow and other thing. It just felt like such a natural thing to me, but after living in China I can confirm that it makes a big difference.

[@turritopsisrockola]

I have been like 10 times to the US and it's one of the things I'm mostly dissapointed about my country here in Latin America not being able or wanting to do. The timing in the traffic lights here terrible, all disorganized, very frustrating

[@ApemanMonkey]

The Chinese took that lesson and ran with it: they are now filming everything and everybody.

[@kevintheomanharris]

I lived in South Africa for a bit 10 years ago....and yeah, I'm pretty sure I never saw any traffic lights with any sort of vehicle detection. All were just on timers. For busy intersections during rush hour, five days a week, they'd turn the light off and have a human direct traffic.

[@Nicholas-f5]

@@turritopsisrockola We likely do it better here to help keep the economy moving

[@reddcube]

Some city buses also use antennas to communicate to traffic lights. “Pulse” bus lines change the transit signal priority at intersections. It can shorten red lights or extend green light based on the schedule and when it’s done loading passengers.

[@closmasmas9080]

I’m pretty sure the ambulances in my area use something similar to that because they alway use this one intersection to turn toward the hospital, and the lights always turn red for all directions when they approach

[@chris-hayes]

@@closmasmas9080 yeah that's done almost universally in cities. There's a small black thing that looks like a train signal mounted near the stoplights, it looks for a very specific sequence of flashes emitting from the ambulance, if it matches, the lights turn green. It's been around for decades, it used to be a lot less sophisticated where you could flicker your high beams and it would trip.

[@thecloneguyz]

@@chris-hayes I use a laser to trip the sensors for me when the light won't turn green or I'm in patient

[@TexasHighwayMan]

@@chris-hayes - There's also a system now that uses GPS to monitor the location of emergency and transit vehicles and notifies the signals to change as they approach.

[@Nicholas-f5]

@@chris-hayes there's a clear light on emergency light bars that they use for this

[@enterpriset]

The traffic control to protect the workers while they cut the loops is probably the most expensive part of installing them.

[@TheEDFLegacy]

Assuming that use traffic control. In my city, there isn't enough traffic to warrant their use. The one time I cut loops, we simply had our own cones and lights and proceeded to work away.

[@enterpriset]

@@TheEDFLegacy Yikes! That would be illegal in my part of the world. It would violate workplace safety regulations.

[@Nicholas-f5]

@@TheEDFLegacy against the law in the US, unsafe

[@jovetj]

I've never actually seen _round_ loops before. It must be a California thing. They're usually rectangular or octagonal.

[@enterpriset]

@@jovetj Interesting. It's nearly all we use where I am!

[@EllieODaire]

Over the road truck driver here. When you said there's a saying that you've heard in every state I immediately thought of the "wait 15 mins" saying and cackled loud enough to annoy my roommate when that was exactly what you were going for 😂

[@atsdroid]

Dang! Who knew highway engineering could be so much *fun* ?! Well done, Rob! Your videos are the embodiment of the ideal that literally *any* boring subject can be transformed into an interesting, inspiring, and fun to discover subject, just by the right presentation. MORE, pls!

[@Rompler_Rocco]

🚦📈 Looks like the algorithm is finally giving RGR his long overdue green light 👍

[@andrewgraves3109]

I love your RadioShack volt meter. I miss RadioShack. 😥

[@trent6319]

This and Not Just bikes are the best channels on youtube

[@jovetj]

5:00 All electric current (except in a superconductor) produces a magnetic field around that conductor. Loop the conductor around in a coil and you intensify that magnetic field greatly, because they are all additive for each turn of the coil. Stick a magnetic metal into the middle of that coil and you'll really _really_ boost the magnetic field of that coil. Inductors like this store energy in the magnetic field...when the power is shut off, the magnetic field collapses, and it turns back into a bit of electricity in the coil as it does so. (Fluctuating magnetic fields can induce electricity in a conductor.) That's how detector loops work. The supervising device puts pulses of current through the loop, and then detects the "magnetic field collapse" is afterwards. If a car pulls over the loop, the collapse will be stronger, and the device can detect this.

[@plumokin5535]

I work at the Sarnoff location! Seeing the building was a happy surprise! I didn't think they would be involved, but that's super cool!

[@robertdooley8272]

Those sensors in the roadway are actually pretty sensitive!! Ive personal experimented this with the signal lights on my way to work, btw i ride a bicycle to work. I noticed some lights would legitimately not change if i stayed on the bike path. So i would have to run a light with NO ONE around me lol. So i thought about riding in the bike lane untill i got to the light, then i would just ride over the circles cut into the road and BOOM!! The light changed!! Been doing it for 8 months now with the same 6 signal lights i cross

[@blitzn00dle50]

I've started leaning my bike over and getting the front gear to set off the induction loop, since just riding over them doesn't work where I live

[@wmcomprev]

With all the computer technology and sensor technologies that exist today, many cities need to improve this a lot. I frequently see 2 big issues. 1) The light doesn't know whether or not a vehicle is there, it knows that the vehicle was there. For example, a vehicle comes up and stops then makes a right-turn-on-red. The vehicle has been gone for several seconds when the cross-traffic light turns yellow. I can see that it's not possible to get the timing perfect, but when it's been gone for several seconds, there's NO reason to be stopping the cross-traffic. Also, it should detect the amount of cross-traffic. If there's not much and the stopped vehicle is in a right turn lane, it may delay stopping the cross-traffic to give the stopped vehicle a chance to make a RTOR. It can't do this forever, even if there's not much cross-traffic coming, since some vehicles are prohibited from making a RTOR (school buses, tanker trucks, etc.), but they should be able to come up with a reasonable formula for this. 2) It needs to be able to detect a vehicle approaching, not just one after it has arrived and has to stop. It should also be able to detect how many vehicles are approaching on the cross-street and calculate the best timing to keep as many vehicles moving, if possible, but not to the exclusion of the stopped vehicle.

[@alinatheduck583]

y’all Brian Girardot is my dad! he killed this 😌 and so did you Rob! thanks for the great video!

[@hannahlopez9605]

he slayed

[@alinatheduck583]

hannah lopez periodt 😌

[@MirzaAhmed89]

How come you spelled his name wrong?

[@jimpeel]

I worked at Odetics back when we made spaceborne tape recorders. I was the drafting coordinator for the Space Shuttle Mass Memory Unit and High Data Rate Recorder under Gordon Schultz and Crandall Gudmundson. That was back in the days of the Odex robot. Iteris started out as Moxon.

[@Darknamja]

While driving in Germany in the '70s they had radar detectors on poles at the traffic lights in the cities to detect vehicle traffic for light changes. It was really apparent late at night when you encountered a red light and there was no cross traffic. The light would immediately turn green. 👀

[@RoadGuyRob]

Leave it to the Germans to make driving precise and rewarding. 😀

[@michaelmccarthy4615]

Almost all traffic lights are LED now. There are pros and cons to these also.

[@pdc-cp4uv]

There are drawbacks to radar as well. Heavy rain or snow will make them inoperable.

[@Nicholas-f5]

@@michaelmccarthy4615 cons?

[@michaelmccarthy4615]

Its small, but snow and ice build up on traffic lights occasionally. LEDs don't produce enough heat to melt it away. Incandescent lights cycle enough heat. Its been a problem in colder climate area's.

[@0311Mushroom]

I am old enough to remember when the switches were mechanical. Rubber strip embedded in the road, about 2 feet front to back and the width of the lane. Pressure from the tires activated them. Have not seen those since the 1970s though.

[@lberry750]

I remember, as a kid, taking a running leap and landing on the plate to get the light to change (small town…so there was usually no one around to cause a hazard.

[@DavidTurner1]

Whenever I am at an intersection without any cars waiting for the light, I tip my steel bike frame over the loop to ensure that the loop detects me. The more you know...

[@andreyv116]

Some study showed that the wheels over the line that's the edge of the induction loop in line with the thing has the best chance of triggering the sensor. If you have both carbon rims and carbon frame, you're probably in trouble

[@DavidTurner1]

@@andreyv116 No problem with a lugged steel frame. Steel is real!

[@marcusdamberger]

I guess a mostly aluminum bike would also have the same trouble triggering the loop. My Trek is aluminium frame, I believe the rims are as well, the spokes might be steel, but I'm not sure. There might be other all random steel part's, but the bike is 20 years old, before carbon became way more common. I think only high end race bikes with national teams had carbon fiber back then.

[@andreyv116]

@@marcusdamberger I have an aluminum frame aluminum rim bike and its success rate is mostly good. Alignment with the coil is important

[@QuinnHartmann]

I saw a tip for motorcycles and bikes that involves a strong magnet stuck to the bottom of the frame

[@scotchbox]

Love how much work you do on these videos :)

[@professional.commentator]

I love the quality of your videos! They are very informative and straight up TV production level.

[@web5271]

We were using video detection in Atlanta 35 years ago. More reliable than loops which crap out whenever you do a mill and inlay.

[@nick4506]

I've been dealing with low sensitivity loops on my motorcycle and a trick I've found is to glue strong rare earth magnets under the toe slider and wave your boot over the edge of the loop. this works with bicycles as well. and if all else fails hop off and hit the crosswalk button. also, fun thing I was spectating at the long beach grand prix, and the indycars riped out the loops on the track from their tire grip.

[@robertmills2900]

At some smaller intersections, I would have to flash my brights to get the sensor to "see" my car.

[@wanderingjana891]

Have that problem with my car and a certain left turn lane. Three cycles just sitting at the line and then I just went.

[@thecirclekkid]

This is because of a tube sensor that detects flashing strobe lights on emergency vehicles in some cities that have square strobe lights mounted on their vehicles.

[@belgianfsgamer]

The saying “if you don’t like the weather, you just wait 15 minutes” is different from what we say here in Belgium. Here we say wait 5 minutes and if it isn’t over you better wait until tomorrow

[@bdp1966]

Wish they worked like this where I live,you can be at a red in the middle of the night with no one else around and sit at the red for at least five minutes before it changes

[@Martin-wj2if]

Thanks for this interesting video. We have detection systems that detect rain, so cyclists get a green light more often during bad weather. This is on roads near the city center with loads of cyclists.

[@JB-zn1kx]

In the mid 80's a dump truck driver in Ohio figured out that if he'd cut the loop wire that it would disable that section and he'd always get a green light in the other lanes.... he didn't count on traffic cameras watching those intersections as well. He got a heafty fine.

[@geraldhuntermusic]

10:30 Cameras now can see better in fog than our eyes because they can composite multiple "frames" together into one image. Since fog is made of particles that are moving the camera can create a more complete image since different details are visible in different frames. It's the same technology used to restore old videos and movies. It doesn't work on a single image obviously, but since traffic cams are video, it makes sense

[@MadnessOfMonkeys]

I was having a conversation about why timers are still used for some traffic lights and it made me remember this video. After double checking that it was not mentioned in this, I pose the question to Road Guy Rob: why do some places still use timers for lights? I live in Milwaukee, WI currently, and it seems that many of the lights are on timers

[@jbrnds]

Here in The Netherlands in The Hague it is mandated that *every* traffic light is smart in detecting traffic and optimise its flow through series of lights.

[@RobPenguinsSince78]

Just found your channel today, watched about 4 videos so far. I have one complaint about loop detectors, they are awful at detecting motorcycles. I have ridden them on the streets for 30 years and almost all, if not all, do not sense the motorcycle even when the opposing traffic was non existent. I would occasionally need to just run the red after waiting a few minutes if another vehicle did not arrive in the opposing lane. The cameras are so much better with motorcycles.

[@garcjr]

Same here I've been binge watching the channel. Yes traffic cameras are better for motorcycles.

[@ThomasBomb45]

This type of technology is best when used to give publoc transit like busses green lights. Making transit more desirable, incentivizing less people to drive which makes traffic better even for those who dont take transit

[@macbuff81]

You could also create round-abouts which slow down traffic, reduce cost and help with reducing accidents. Of course, it doesn't work for every intersections, but for many it does

[@Eliasgamer566.]

as long as theres space and a good amount of traffic, i can agree

[@davidfrischknecht8261]

I was born and raised in New Jersey and I never heard anyone say "if you don't like the weather, just wait". I have heard people say it about the mid-west, though.

[@joehung1552]

I've heard it in Jersey. It's usually just wait it'll get worse.

[@fjb4932]

It's Always sh¡++y in Joy-see ...

[@brianbrianbrianbrianbrianbrian]

Great video, Rob. Your video editing/production is really improving and the content (along with your personality) has always been great. Keep it up! Looking forward to the next video.

[@josephgaviota]

When I was a kid (back in the early-to-mid '60s), there were a couple signals in Burbank, CA which had what I assume was "sonar." There was a sort of "plumbing fixture" two-holed head at the side of the road with two openings about 1-½ inches, with mesh screens over them. We could _clearly_ hear the "tick tick tick tick" coming from one hole; and I assumed (as a slightly bright kid might) the other hole was the "receiving" side. Based on the reflection of tick tick tick, (like how a bat flies), it "knew" a car was present. Specifically near Lockheed Airport (as a kid).

[@tolson57]

VF-211 Tomcat NICE! I as in the Navy for 20 years and I worked on the Television Camera System (TCS) that you mentioned in this video. It was beautifully designed but was a bear to align but I loved the challenge.

[@ghostfox3560]

What the one guy said at 11:00 is rather nice to hear. Might reach Illinois and Wisconsin someday. Our traffic controller systems seem lacking for a lot of bicycle friendly detecting. And no cyclist likes having to choose between waiting 40+ minutes and safely crossing an intersection.

[@spaghetti9845]

It always amuses me when I sit at a light and see people flashing their high beams at it because someone somewhere told them the sensor is on the pole.

[@NotSoCrazyNinja]

There is a local intersection right in downtown of a growing town. It has a main street (lots of traffic) and the side street intersecting it (almost no traffic). The stoplight at that intersection gives priority to the side street for unknown reasons. It causes a lot of traffic jams and this has been going on for over a year. I suspect they set it like that on purpose to get people to stop at that intersection because that area is where a lot of local businesses are and if they stop a lot of people, it gives those people a chance to see those businesses. I can't tell you how many times that intersection has stopped me while going down the main street with absolutely no traffic on the side street.

[@jeffrittenour8202]

This video is why I don't own a television. Keep up the great content. Your channel is awesome!

[@HelloKittyFanMan.]

Yeah, right, I'm sure you sold/gave away your TV right after seeing this video and vowed never to have a TV as one of your computer monitors.

[@e.alexaquino8112]

I have become obsessed with this channel and I don’t know why. I’ve always wondered about these things and there is a high quality channel doing this. Thanks dude! Keep it coming!

[@AdhamOhm]

A lot of the traffic lights in my city seem to be biased against the heavier traveled roads. For example the green light on the main road is on just long enough to let five or six vehicles through before it goes to yellow then red. Meanwhile the lesser traveled crossing street gets a green light for the one or two cars that are waiting, and that light *_continues to stay green_* for almost a minute after that. I'm guessing the idea is to break up traffic on the main road, but that strategy doesn't seem to work because now you have a conga line of vehicles with impatient drivers behind the wheel waiting to floor it next time the light goes green.

[@andybrice2711]

The thing about Britain is that if you don't like the weather, you just wait 15 seconds.

[@wmcomprev]

When closing lanes, the traffic light computer should be able to be told that a particular lane or lanes is/are closed and adjust the timing of the light to allow for traffic to merge.

[@chubbyadler3276]

Something I would like to know is the purpose of putting a detector on those traffic lights managing busy roads that are instead programmed to turn RED when traffic arrives. We have a surplus of those here in Alabama.

[@blitzn00dle50]

I live in St. Louis, where, and no this is not a joke, the city actually did time the lights specifically to stop people from hitting multiple greens in a row. This is most obvious on the Northern Kingshighway viaduct, where southbound Kingshighway gets a green just as McRee gets a green, which backs up traffic all the way to Oakland and beyond. However, that creates the opposite problem for the northbound side. Someone who gets a green at Vandeventer can end up charging all the way to Interstate 64. However, that's not as bad, since there's much better visibility and less conflict on the northbound side. Someone on westbound Manchester who wants to turn right can see all the way down the viaduct and then some, up to Interstate 44. The reason they did this was because there were too many fatal car accidents involving speeders, which they figured wouldn't happen if everyone was crawling through the intersection as one massive 90 car long platoon. That worked and now St. Louis has an abnormally low rate of traffic fatalities despite an abnormally high rate of total accidents. Personally I'd rather have them just remove conflict points on roads and physically slow down streets but this is a pretty smart temporary solution

[@roy_hks]

In Europe all traffic light crossings have sensors in the roads, both for cars and cyclist so we never wait unnecessarily at a red light. Again great video and great that it’s finally gaining popularity in the USA.

[@minnesotarc7964]

This is a great video and a fantastic channel for roadway and highway infrastructure. MnDOT is a perfect example of the loop detector. During the PM rush hour the light will take forever to prioritize the state highway. The same highway intersection at 1AM will change immediately when my car or another car is detected. Minneapolis is an example that still in some intersections uses time-delayed signals and the light will be red at the same time interval at 5PM and 2AM, though i think they are moving towards video detection and some loop-detection in major intersections.

[@connorlynch4252]

I knew there were loops under the ground, but I had never considered the trade offs between the induction sensors and cameras. Thanks for share all this great info!

[@thelastword71]

You honestly deserve more subscribers with this production quality.

[@AndrooUK]

Unless people don't give a shit about transport and such?

[@jovetj]

He'll get them.

[@charliestyle575]

I can finally die in peace now. I swear I've been wondering this since I was a little kid.

[@kavalerdivacom]

The 2 second picture of the magnetometer is something I invented and started the company Sensys Networks which competes with video very well. The magnetometer doesn't have any magnets in it, it measures the earth's magnetic field. I also invented a microradar that mounts in the ground and can detect bicycles and pedestrians much better than a camera. We now have a phone-based app that bicyclists can use to get green called GiveMeGreen.

[@nunyab8003]

Very cool! Any good stories?

[@lifeintornadoalley]

As someone who was part of a family who ran a city for over 2 decades... The best perks I've had as being a "gifted person" of the city was the master remote. When we upgraded our traffic lights to accommodate the updated dispatch equipment (dispatch could track real time where EMS, fire and police services where anytime, they could hold red lights to clear traffic for a clear route for the services) we also got remotes. Before the services did so we could test them out (Mayor, council members). Being a stuck up kid running around the city with this remote, I'd troll officers sitting at lights. They'd think weird stuff when my light was yellow back to green. The frequency was close to some audio equipment police used too. So a click would make a weird noise on the CB's. You can imagine the meeting the mayor had once the Mayor made the remote public to services. None of the services where happy council members got first dibs

[@pardn]

Cameras still suck so bad at night though. The city I used to live in is notorious for using particularly bad ones. At some of the intersections that have them I would be waiting over ten minutes for the light to change but the camera would never detect me.

[@vV4L1UM]

you would never think they're this complicated

[@dustinsorge]

Keep up the incredible content. These videos are always a great watch and super educational.

[@drumset09]

In Alaska, if you don't like the weather, just wait 5 minutes, it'll get worse. Great video, especially with the history of pressure plates.

[@Kamel419]

I have *never* used one of these regularly that had satisfactory performance. My current road I have to do a constant slight movement forward/backward until I find just the right spot. Many times I've had to turn right then u-turn, and one time I just ran the thing after waiting for 10 minutes with no cars coming. Only time I've ran a red light in my entire life. Infuriating.

[@Saki630]

fuck man this is a professional production for a TV spot.

[@roncross1945]

Hey Rob, I just discovered your channel. Great job. By the way, Mohammad and I were on the same carpool back in the late 90s. Funny, you never know who you’re going to see on KZbin!!

[@ap70621]

I had no idea loop sensors were around so long. There was an intersection in North Jersey I would pass through a lot that had a permissive left signal. It would only give an arrow if at least two vehicles were in the left turn lane. I found one day that I could "trick" it into giving an arrow every time even if I was the only one in the lane. There was a loop sensor just beyond the stop bar, if you pulled over that one, it would give you an arrow. It has since been replaced with video detection.

[@odo324]

Corner of Dries and Forrest Hill in Peoria, IL changed their signal detection recently. I think my city is trying to discourage use as a through-road because this light now prioritizes the side-street Dries over the main street Forrest Hill. While I appreciate the discouragement of traffic I get stopped here nearly every time to/from work for one car turning right (yep, turning right). I suspect it is actually to help improve those going in/out of the corner activity center called Landmark (exercise center & movie theater) on Dries.

[@leafbelly]

There used to be a tiny side street in my hometown (less than a block long) that intersected a four-lane U.S. highway. Because of the huge disparity in traffic between the two, I found out that it had a detector on it. So, one afternoon when I was about 9 years old, smart-ass me and some friends were bored and decided to go ride our bikes over the detector -- over, and over, and over, and over again -- forcing the light on the U.S. highway to stay red about 95% of the time. Needless to say, the highway drivers weren't having it. After about 10 minutes of this, a semi-truck driver jumped out of his cab at the red light and started hauling ass chasing after us, calling us everything he could think of and threatening to kick all our asses. Yeah, we probably deserved it, but I'm not sure how it would've looked having a 40-year-old trucker assaulting a bunch of 9-year-old kids. haha

[@RipleySawzen]

I just wish they'd make the prediction better rather than seeing me a half mile down the road and turning red RIGHT as I get there.

[@martinusher1]

The signals I grew up with in England used two tubes close together, often covered with a single rubber strip. This could not only sense the direction of the traffic but also potentially its speed. (In the 1930s there was one experimental 'green wave' system that I was aware of, one of those 'if you kept to x mph then you'd never hit a red signal going through this town). As a horrible little urchin I used to like stomping on the tubes to make the lights change. As a motocylist in today's USA I dread the coil detectors. You rapidly get to know which ones won't see you and adjust your route accordingly -- it gets boring wating for a car to turn up.

[@wadesanecki7269]

Not a bad video. Next one could perhaps show how delays are put into place such as in right turn lanes so unless traffic is heavy, there is no need for the light to change. Also, include extension loops placed in advance of the intersection that tells the controller that a car is close, and the light stays green a little longer, till it clears the intersection. The modern versionof this is radar, that not only picks up the car, but tells the controller the speed of the car, thus the controller knows how long to extend the green phase.

[@RoyalWolf17]

I appreciate the effort you put in these vids. You make learning fun 👍

[@eagle4life69]

Love that a lot of the video shot was from my area. I kept recognizing different locations in the IE

[@MarkReviews]

Amazing video! You're doing incredible work on this channel. Keep 'em coming!

[@Nokoa]

Great video. I don't know if you had done a video on pre-emption for emergency vehicles, but I would love to see something about that. My city has radio and GPS based ones. I have seen neighboring cities using Opticom with the infrared detectors.

[@coreybabcock2025]

Definitely would try this

[@dylanwebster2656]

Just noticed this dude was walking in my hometown because of a sign in the background. Very cool!

[@razorswc]

Very good. Cant wait for the radar video.

[@Sparky5]

While the detector software is using the cameras for signal control, police also have a feed to the cameras and monitor traffic as they would a normal camera, but not for citation purposes. Those are another set of cameras and a different topic altogether.

[@ilovetotri23]

I feel like timed lights were more effective. However, accounting for all possible intersection control is a job far above my station in life. Thanks Rob!

[@JULYXXIV]

I really like how California displays their signal heads. I think they just look classier. What I find interesting is HOW California has their signal heads mounted to the mast arm (the overhanging bar). Are they really bolted to the mast arm between the red and yellow sections?

[@pappaslivery]

As a motorcyclist, I know where many old loops exist in my area. I often pull forward and then wave a car behind me to pull close to set off the lights

[@gjforsman]

In some areas of WA state, there is a X painted an the best place to put your front tire to trigger the induction loop.

[@pappaslivery]

@@gjforsman yeah, many of the newer ones have a bicycle stencil where it is more sensitive. But there are some less sensitive ones around. One is to trigger a left turn at a semi divided highway with lights. It's an old awful design. I need a car to trigger it for me when I'm on the bike.

[@robertheinkel6225]

Makes sense as long as the car understands what you are doing.

[@edrose5045]

I might just try to add a little more detail to the car detection loops theory of operation (prefixed that this is based on educated speculation rather than a deep understanding), in case anyone is interested. The way that it's described in the video requires the car to be both a magnet, and to be moving. Cars aren't static magnets, so the way it's described doesn't really work. What happens is that a small high frequency AC voltage is applied to the loop of wire, which in turn produces an alternating electromagnetic field that reaches up out of the road. When any metal (like a car) is placed into this magnetic field, the electrons in the metal start moving. This is very similar to how a transformer works but instead of the electrons moving through a wire on the other side of the transformer, they move in the metal body of the car. These are called "eddie currents". These eddie currents are incredibly tiny so don't cause any problems for the car, but in theory heat the metal up a tiny (insignificant) amount. If you think about this from a conservation of energy point of view, those eddie currents are heating the car up, and that energy has to come from somewhere. The result is that electric potential energy is bled out of the coil and converted into heat energy in the metal of the car. The result is that the voltage in the coil gets reduced since it's energy is now being used to heat the car up a small amount. This is similar to how induction hobs work. -- More technical explanation -- From a more complex electromagnetic point of view, the magnetic field that the the coil in the road produces actually produces it's own force on the electrons in the coil that created it in the first place. That force on the electrons is actually opposing the direction to the current generating the magnetic field. The force isn't enough to stop the current completely, but limits the current flowing through the coil compared to what it would be if the magnetic field didn't exist. We call this kind of resistance to current "impedance", and the impedance (and therefore final current in the coil) depends on the magnetic field strength that the coil is experiencing. When some metal like a car is inserted into the magnetic field, eddie currents are produced in the metal body of the car. They actually start generating their own (weaker) magnetic field; however this magnetic field acts in the opposite direction to the magnetic field of the coil, so it cancels out some of the magnetic field that the coil produces. This means that the magnetic field that the coil is experiencing is reduced, so the opposing force on the electrons (impedance) in the coil also reduces. This reduction in impedance causes an increase in current flowing through the coil, which can be detected as a drop in voltage across the coil whenever there is metal in proximity to it.

[@ryans413]

Dead of night I’m at an intersection it’s a red light no ones around but me sitting at this light for probably over 5 minutes thinking is this thing broken. So I decided to back up a little no ones behind no ones around when I did that light changed green. Now I don’t know if that was something I did or it just changed on it own but 5 minutes is a long time to sit with no change and I live in a small city the light change quick.

[@DosEquisGuy3]

Traffic lights should never change for drivers that are turning right

[@toshley6192]

Depends where you live. Some places it's illegal to turn right on a red, especially in the US.

[@puzzle.86]

@@toshley6192 no its not

[@jodybanks5344]

Bull spit

[@jeremywj]

​@@puzzle.86 There are a good number of right turns in the US that are illegal. If so there is a sign saying so. To further complicate things, some right turns are "sometimes" illegal. For example, you'll see signs saying "No right turn on red when children are present" or "no right turn on red between x hours"

[@user-ps4lx8qq2c]

@@toshley6192 Unless it is stated you can't, you can make right turns in the U.S.

[@EdEdoEddie]

I watch your videos way more than I ever thought I would.

[@dallasarnold8615]

How about doing a video explaining why many jurisdictions are going to a metal arm for traffic signals as opposed to the old style cable across the road. Seems to me that cables are less expensive and easier to repair. The arm seems crazy expensive to me, since they use tapered post and arms, which I know is for strength but more expensive than a pipe with a constant diameter. It does occur to me that mounting cameras on cables would likely be impossible due to movement of the cable.

[@kdmq]

I guess cameras are most useful in busy intersections where you have 3 lanes or more each direction and places like levees and bridge embankments where the slight water leakage from an improperly sealed loop could wash out a section of the road.

[@David619K]

Very underrated channel. I've learned a lot since subscribing. Keep it up Rob.

[@classicmusic6925]

Bro your video's feel just right for a tv show i ll watch all day in my life

[@HelloKittyFanMan.]

His video's _whats_ feel just right for a TV show (which possession, which thing that belongs to his video)?

[@josephgaviota]

Hey Road Rob, I've never seen one of your videos, but this was REALLY interesting, and I'm sharing it with my siblings and friends. XLNT vid.

[@malachimarko7963]

My favorite is camera because here in my city idk if it's the same in others and this is the beginning of the video but they can be used to see what happened at a car accident it's amazing

[@shredern]

I am so glad ive found this channel.

[@appleguy1986]

Great job, Rob! Keep it up, you are smart, you are funny, you are entertaining, your content is interesting. You are going places.

[@jamesr2888]

Two things. I remember when the "loops" that were cut into the asphalt were square mostly in the 80's & 90's. Now they're round. I asked one of my local public works guys if the loops detected vehicles by magnet or by weight. He said weight. Here he says magnet. Which is it?

[@Bendigo1]

It could be both. The old ones may have been weight but now by magnetic

[@Nicholas-f5]

Only really old ones were weight

[@YehudaKatz1]

We have an intersection near me with a traffic light on a big curve. They used to have loops further around the curve to measure how many cars were waiting, but when they switched to cameras, they only put one right at the intersection - traffic backed up for a mile because the intersection computer thought only 5-7 cars were waiting instead of dozens. I called the traffic engineering department and they apologized that they didn't think of this issue...

[@elviswjr]

I see lines on the road and cameras on the poles at intersections here in the Phoenix valley but I swear, every time I pull up to a red light, regardless if anyone is around, I still have to wait ages for it to turn. Also, we have pedestrian crossing traffic lights at canal and path crossings. When a pedestrian pushes the button and changes the light, the traffic has to wait a set amount of time before it changes again. I think they should come up with pedestrian detectors that automatically change the light to green or off when it's all clear instead of making us wait.

[@DavidJamesHenry]

I'm from the Central Valley, my hometown of Reedley has been taking advantage of the lockdowns to repair so many roads in town, including new traffic detectors

[@xRadio2006x]

so YT just so happen to recommend this video and a question I had earlier was answered. I saw a cable through the roadway outside my office when driving home and I was wondering what it was and what information was gathered...i always thought it was some type of speed thing...thanks Road Guy Rob!

[@carolinaeric8500]

I always wondered how all of this works. Thanks for the video! Around where I live I have noticed the cameras up there but thought maybe they were for monitoring the intersection for accidents and what not, now I know they are part of the traffic signaling, not that I was worried I was being spied on or anything lol

[@Nicholas-f5]

They have both kinds