Traffic signal

[Alps]

If a sensor loop detects something over it for an extended period of time, will it ignore the approach?

This typically happens with video, but it can happen with loops too. The video fuzzy logic looks for changes in the pattern. If it detects a change that doesn't move after 3 (ish) cycles, it turns the change into background and assumes it's permanent. (Could be a new tree on the corner, snowbank on the sidewalk, who knows?) If loop detectors are set up with advanced logic, they could look at changes in induction over time rather than strictly compared to a baseline.

[roadfro]

If a sensor loop detects something over it for an extended period of time, will it ignore the approach?

This typically happens with video, but it can happen with loops too. The video fuzzy logic looks for changes in the pattern. If it detects a change that doesn't move after 3 (ish) cycles, it turns the change into background and assumes it's permanent. (Could be a new tree on the corner, snowbank on the sidewalk, who knows?) If loop detectors are set up with advanced logic, they could look at changes in induction over time rather than strictly compared to a baseline.

The flip side of this: if there is a loss of detection capability (i.e. the loop gets cut), the controller often registers it as a constant call for service and usually runs that phase to the maximum green setting.

[Alps]

If a sensor loop detects something over it for an extended period of time, will it ignore the approach?

This typically happens with video, but it can happen with loops too. The video fuzzy logic looks for changes in the pattern. If it detects a change that doesn't move after 3 (ish) cycles, it turns the change into background and assumes it's permanent. (Could be a new tree on the corner, snowbank on the sidewalk, who knows?) If loop detectors are set up with advanced logic, they could look at changes in induction over time rather than strictly compared to a baseline.

The flip side of this: if there is a loss of detection capability (i.e. the loop gets cut), the controller often registers it as a constant call for service and usually runs that phase to the maximum green setting.

It's not so much "registering as a constant call" as "defaulting to maximum recall." When the system knows there's a problem and it won't be able to detect traffic, it switches to default and notifies central command (if there is any).

[roadman65]

Does anyone know why with all the modern technology and inventions, why detector loops are so slow in response in certain situations?  I noticed that when I leave my subdivision on to the highway that has our main street and the arterial where there is a another automobile on the other road already activating the detector and his light begins the change process AFTER I come to a full stop at the stop bar, I have to wait another light turn.  In other words the signal completely ignored me even though I was there before the cycle began setting.  I can see if I activated my detector loop when the signal was already set in motion for me to have to wait, but not when I have arrived at the stop bar a second or two before the light set itself up for his signal to turn a green arrow.

I thought this was a rare case, but today I was screwed out of a protected left turn arrow at another intersection near my job.  In this case I had already arrived at the stop bar only one second before the light on the side road began to turn yellow.  I would think that the computer would already figured out that I am there as things can happen at the speed of light when it comes to electronics, and even if you arrive at the intersection when the cycle already started, it should be able to reconfigure in less than a second.

Are they designing signals to be slow or stupid instead of following the God of technology like we all do each day?  That seems too old fashioned for me and I find it hard to believe the slow response.

[SignBridge]

There is more to this than meets the eye. Signals are programmed to respond to a variety of different circumstances and criteria, that's not always obvious to us drivers. I believe some are also synchronized with other signals along the main route, so it may be doing what it does for reasons not readily apparent to us frustrated drivers who just miss the arrow. I often share your frustration.

[ARMOURERERIC]

I've seen programming where it waits a few moments to see if you do a right turn on red so it does not need to change the signal

[DaBigE]

I've seen programming where it waits a few moments to see if you do a right turn on red so it does not need to change the signal

That would be an example of non-locking vs. locking memory.

[tradephoric]

I thought this was a rare case, but today I was screwed out of a protected left turn arrow at another intersection near my job.  In this case I had already arrived at the stop bar only one second before the light on the side road began to turn yellow.  I would think that the computer would already figured out that I am there as things can happen at the speed of light when it comes to electronics, and even if you arrive at the intersection when the cycle already started, it should be able to reconfigure in less than a second.

Here's an example where this situation could occur.  If an inductive loop left-turn detector is getting clipped by opposing traffic a delay will often be inputted into the controller.  A 3 second delay on the left-turn detector will help prevent a call being placed into the controller when the left-lane gets clipped.  However, the solution to the clipping problem creates the scenario you just described. 

[Scott5114]

This happens all the time on SH-9 in Norman. There's a left turn bay going eastbound that literally goes nowhere (it leads to a cell phone tower). Sometimes eastbound traffic will clip the detector loop, causing westbound traffic to get held up for no reason.

[tradephoric]

Here are the different detection setups:

Locking detector w/no delay. The instant a vehicles passes over the detection zone a call is placed in the controller until the call has been serviced regardless if the vehicle that placed the call has left the detection zone.

Locking detector w/delay. A locking call is placed into the controller only if a vehicle is continuously detected beyond a preset value (the delay value).

Non-locking detector w/no delay.  The instant a vehicle passes over the detection zone a call is placed in the controller.  When the vehicle leaves, the call drops.  With this setup a vehicle is serviced only if they are detected during the controller's "decision point"  to switch phases.

Non-locking detector w/delay.  Same as non-locking detector w/no delay, but the non-locking call is placed into the controller only if a vehicle is continuously detected beyond a preset value.  The call is dropped the moment the vehicle leaves the detection zone.

A locking detector w/no delay would most likely be used at a dedicated thru-lane or protected left-turn lane detector (where clipping isn't a problem).   The benefit of this setup is that it's the least likely to miss or skip a legitimate vehicle call.  The disadvantage of this setup is that it's the most likely to lead to false calls (I.E. clipping vehicles, right turners who have already left the intersection).

A non-locking detector w/delay would most likely be used for a dedicated right turn lane where right turns on red are permitted.  The benefit of this setup is that it's the least likely to lead to false calls.  The disadvantage is it's the most likely setup to miss or skip a legitimate vehicle call. 

In the end, efficient signal operation is often sacrificed to service the lowest common denominator driver.

[theline]

Great explanation! I've often wondered. Thanks.

[SignBridge]

Right, thanks Tradephoric; very interesting info.

[roadman65]

Are we roadgeeks the only ones who report malfunctioning signals to the road agencies?  The signal at Orange Blossom Trail and LaQuinta Drive has been shortchanging NB vehicles on OBT when a SB motorist turns left onto EB LaQuinta it does not turn green at all, but turns green a second time on LaQuinta Drive causing long waits for NB OBT.

You figure some blowhard would report this problem after 6 months of happening.  Thousands of cars and trucks pass through this everyday and not one is saying anything!  No wonder why the world is in trouble.

[SignBridge]

The answer to your original question may be "yes".  Example: A signal in my neighborhood at the intersection of a 4-lane county road and the driveway to an office bldg. on one side and a courthouse parking lot on the opposite side. Normal operation is continuous green for the county road unless activated by a vehicle coming out of either driveway driving over what I believe is a no delay/locking loop detector.

A couple of times in the last 10 years it's malfunctioned and activated repeatedly even when no car drives over the detectors, causing the signal to change periodically for no reason. The local police have a shift-change point in one parking lot and must pass thru this intersection 20 times a day, and do you think they report the problem? No!

After a week of this malfunction I finally called it in to the county traffic dept. and a service-man arrived 2 hours later and made an adjustment that corrected the problem. So yes, I guess only us roadgeeks notice or care enough to call these things in.

[jeffandnicole]

When I talk to other people about roads, most people incorrectly mention the agency that they believe is in charge of the the roadway.  In most cases, people believe the county is in charge of what are actually state roadways.

Even when I was at a township council meeting, I wanted them to push the state to do something about a specific traffic light.  Because the traffic light was at the end of ramps to a state limited access highway and the intersecting road was a county road, they insisted the light was county jurisdiction.  While I politely informed them any which way I could that it's actually a state light, they would only pursue my issue with the county.

BTW...nothing ever got done.  I wonder why!

[SignBridge]

Scary isn't it?

[PurdueBill]

Even when I was at a township council meeting, I wanted them to push the state to do something about a specific traffic light.  Because the traffic light was at the end of ramps to a state limited access highway and the intersecting road was a county road, they insisted the light was county jurisdiction.  While I politely informed them any which way I could that it's actually a state light, they would only pursue my issue with the county.

BTW...nothing ever got done.  I wonder why!

I've dealt with that kind of thing and nothing ever got corrected....this intersection at an interchange on I-76/77 has the evidently wacky Yield sign that faces traffic that just came through a signal either by left turn from Wolf Ledges or straight through on the frontage road, with traffic from the right that also has a signal.  The Yield sign is silly facing the way it is.  (People with a green light on the frontage road going straight through see a yield sign too.  Yield to what?  I was not the only one to inquire to ODOT about it and they insisted that despite the ramps being ODOT territory (despite the city being responsible for regular maintenance issues), the city owns the intersection (evident by the Akron city signals) and there is nothing they could do about the sign, even though they agreed with me that the sign was nonsense.  Finally the sign was knocked down and for a time put back up facing the traffic turning right onto the ramp, but it was soon "corrected" to face the way you see in Street View, with a bright orange "ODOT" marking next to a orange spray-painted circle around the base of the new post.  I wonder what that means?  ODOT wanted the sign put back that way?  ODOT is coming to replace or remove it?  Who knows.

The city also had erected totally stupid No Turn On Red signs facing traffic turning right onto the ramp, which was incredibly dumb--that acted as a reverse ramp meter, bunching traffic together artificially to come down the already-dangerous ramp instead of more spaced out like they would have been without the No Turn On Red.  The city's reasoning, challenged in the local paper even, was that No Turn On Red increased safety by avoiding conflicts at the intersection.  Maybe some of the conflicts that caused accidents were caused by traffic getting simultaneous green lights and yield signs while interacting with other trafffic?  (that is, see just above.)  Sigh.

[roadman65]

Is somebody ever going to realize that too many traffic signals, not only cause hardship on the roads, but also create safety concerns as well.  When you have to much stop and go it can cause rage in some motorists and other issues.  Plus when you have two traffic lights too close to one antother, a gridlock situation can occur.

A perfect example of two signals that are close together that has gridlock at one intersection is John Young Parkway at LB McLeod Road, and the other less than 1/5 mile north of that intersection at JYP and Clear Way.  The former is a major intersection between two Orlando arteries, but the latter is a street that does not have much traffic and should be a right in and right out, but city officials made a deal with the nearby neighborhood to have a signal for residents to enter and leave their subdivision with ease.  The real thing that gets me is that there was another signal on LB McLeod for the other road leading in and out of the same neighborhood that was removed so this here signal went up in its place.  The previous signal was in a better and safer location and was far enough away from the big intersection to create gridlock conditions.

Orlando, FL is notorious for erecting traffic signals and putting them up everywhere!  There is just too much development going on clogging up all the main roads. However, there is a better solution to this.  They just cannot keep adding lights to every cross road, business driveway, or apartment complex.  There is just too many of them and with Orange County, FL not timing traffic signals the way they should be, adds to this mess.

I lived in New Jersey for over 20 years and NJDOT would not allow too many signals close to each other on major highways.  If one intersection is too dangerous that has low traffic counts like Clear Way in Orlando being too close to another major intersection, a riro would be implimented for sure and the other light (if they were foolish enough to make a deal with local residents in a small subdivision) would have been kept. 

Then there is the Wal Mart Neighborhood signal on Orange Blossom Trail that was bought and paid for by Wal Mart as their contribution to the city to help traffic flow on OBT that is making that artery a nightmare in reality! Plus, where its at is not at a major crossing or legitimate street, but two driveways meeting head to head with one of them serving an apartment complex that has people driving in and out of it 24/7.  One of the things we have problems with is apartments because they seem to attract the rift raff (if any of you live in one of these no offense to you as I may someday live there as well someday as it is very hard to pay for a house) as there seem to be more drug arrests and other domestic desputes in those dwellings then private homes according to police and what you see on the evening news.  That puts more motorists out there in additon to Wal Mart and other shoppers that patronize local businesses there.

OBT is a major highway that does not need more obstructions.  In fact years ago it was a rural highway making travel between Kissimmee and Orlando easy and within 20-25 minuets.  Now, it can take 45-60 or even more depending on traffic.

I think its time to review other alternatives to making roads more accesible and easier flowing.  Make new developers pay a hefty impact fee for the extra traffic they add to the roads and damage they do to the roadways.  In New Jersey on US 1 in North and South Brunswicks, all developers had to add an extra lane to US 1 to even build their establishments in front of their properties.  This way when NJDOT widens the highway at a later date, some of the work is already performed.  Traffic lights are good, but even KSDOT even has a article on their website's Q & A about the dangers traffic signals can also create.  I see the dangers everyday.  Also, hire compitent people to time the signals!  Orlando sucks with their timings especially on Orange Blossom Trail.  I am glad they do not run US 202 in Readington, NJ where NJDOT elimated a high accident intersection with a riro as the crossroads are in a ravine where a signal would create more accidents then prevent them there due to very limited sight distance, or else there would be a traffic signal at Pleasant Hill Road and US 202 if they did.

[agentsteel53]

Orlando

Orlando, FL

Orlando

Orlando

I'm beginning to see the problem...

Orlando sucks

yep!

[NE2]

Oh no, it can't be Orlando, just the apartments and their "rift raff"!

PS: the Turnpike to I-4 gets you from Kissimmee to Orlando.

[roadman65]

Oh no, it can't be Orlando, just the apartments and their "rift raff"!

PS: the Turnpike to I-4 gets you from Kissimmee to Orlando.

Yeah it does, but some of us locals cannot use it.  From where I am located the FL Turnpike is out of the way.  Anyone who lives in the Southchase and Hunters Creek area are right between the middle of two interchanges that you can get on to bypass everything.  Then you have the shunpikers who love to complain anyway, even if they have access to the toll road.  I will use the Turnpike sometimes to go from OBT to Millenia or use it to go from my work to Kissimmee, but others I know do not even make it an option.

[Ace10]

Oh no, it can't be Orlando, just the apartments and their "rift raff"!

PS: the Turnpike to I-4 gets you from Kissimmee to Orlando.

Yeah it does, but some of us locals cannot use it.  From where I am located the FL Turnpike is out of the way.  Anyone who lives in the Southchase and Hunters Creek area are right between the middle of two interchanges that you can get on to bypass everything.  Then you have the shunpikers who love to complain anyway, even if they have access to the toll road.  I will use the Turnpike sometimes to go from OBT to Millenia or use it to go from my work to Kissimmee, but others I know do not even make it an option.

Back when I lived in Orlando, I was hardly in the OBT area, but the few times I ventured into that part of town, I made it a point to use the parallel John Young Pkwy as much as possible over OBT. Sure, JYP had lots of traffic, too, but there are definitely not as many businesses/storefronts and traffic signals on JYP. And there are lots of connecting roads between JYP and OBT. This made my travels in that area a lot more bearable.

If I remember correctly, FTE or maybe OOCEA wanted to build SR 529, which would roughly parallel already-existing SR 527, though I'm not sure how extensive SR 529 would have been, or how convenient it would have made getting from Kissimmee to Orlando or vice versa.

[NE2]

If I remember correctly, FTE or maybe OOCEA wanted to build SR 529, which would roughly parallel already-existing SR 527, though I'm not sure how extensive SR 529 would have been, or how convenient it would have made getting from Kissimmee to Orlando or vice versa.

SR 529 would have been only north of SR 528, where SR 527 has relatively few lights. To the south, the Turnpike makes it redundant.

[roadman65]

My original post on this was that the County of Orange and the City of Orlando are getting overkill with traffic signals.  Sure we have traffic counts that are high due to sprawl, but many intersections could easily be RIRO and you, NE 2, should know yourself that you have to stop too many times to get from one end of Orlando to another.  I also wager, that every time you get nailed at a traffic signal you probably complain out loud, especially when you have to wait a long time for it to turn green when few vehicles are using the cross street.

You know that Orlando is one of the worst in signal timings in the nation.  The signal at the intersection of  OBT and Oakridge, that treats both roadways the same, is definetly timed wrong!  At 8AM you have three light changes to wait for going NB on OBT, when there is far less traffic on Oakridge Road at the time and furthermore Oakridge traffic, if you hit the light right, does not have to wait at all!  Now its been a while, but things may have changed, but I doubt it.  My friend, who works for the county, told me that both roads have to be treated equally as they both are the same.  I do not think so as OBT  has much more volume than Oakridge.  Remember, OBT is a highway and Oakridge is not, even though it a main drag OBT wins out.  Also, when the signal malfunctions to flash mode, did you know that it flashes as a four way red?  One night I was driving down OBT and the light was flashing.  I could not believe that it was red on OBT!  Other signals like Lancaster Road, American Boulevard, and even Holden Avenue flash yellow for OBT if in that particular mode.  Of course you are definetley aware that it is much easier to cross Sand Lake Road on OBT than it is Oakridge Road!  It does not take a genius to see that Sand Lake Road has hundreds of times more traffic than Oakridge does, and you only have to wait one or NO light changes to cross Sandlake.

Orange County does not look at the big picture, but listens too much to local neighborhoods and eventually gives in to their demands.  Heck with the native Floridians who were there first or you guys now have to make sacrifices and not have your expressways anymore as each subdivision and developer has to have his own traffic light. 

I lived in New Jersey, where we did things much different on the same issues.  If two roads were a block apart and one was a major thoroughfare while the other was a small traffic side street, only one would get a light and if the lightly traveled street had issues that warranted a signal, then a RIRO would be created for it!  There are much better solutions and I think we need to start exploring them.  If not we will be like NYC with a light on almost every block.  One thing though, NYC can time their lights better and with old analogue equipment.  Remember, there is no such thing as a detector loop in NY, and all lights are on timers as well.  I have made more signals on 10th Avenue in Manhattan than on OBT or JYP in a place that has more people and cars than we do!

[amroad17]

I remember driving in Manhattan and going down Broadway from the GWB to 19th ST.  I would stop every 10-12 blocks from 178th to 98th then I could get to Times Square without stopping from 98th because of the way NYC does the traffic lights.  Leaving, I would go up Amsterdam and, while sitting at a stop light, would watch the next 10-15 lights change to green at the same time.  Every city in their urban/downtown area should follow this synchonization instead of having a light change to green and two blocks later stop at the next light because of sensors instead of timers.  I always found it better to drive in Manhattan than to drive on the Cross-Bronx or the Brooklyn-Queens.  There may be much traffic (aggressive, sometimes) but it beats a stop-and-go on a freeway/expressway that, mentally, you are thinking "Why aren't I moving on this freeway?  I should be moving!"