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National Boards => General Highway Talk => Traffic Control => Topic started by: KEK Inc. on May 04, 2012, 04:24:01 AM

Title: Timers on Traffic Signals
Post by: KEK Inc. on May 04, 2012, 04:24:01 AM
Edit:  Not Pedestrian Crosswalk timers.  Those are catered to pedestrians.

One of my friends recently went to China, and he told me about the road system there.  One interesting note is that most of the traffic lights have timers. 

(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fwww.ledtrafficlight.cn%2Fvideo%2FLED%2520Red%2C%2520Yellow%2520and%2520Green%2520Full%2520Ball%2520with%2520White%2520Countdown%2520Timer.jpg&hash=872f52d1e2218bca0ff4d790538a3b18534769c5)

(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fvisibleprocrastinations.files.wordpress.com%2F2007%2F03%2F07n.jpg%3Fw%3D500&hash=3976b5272dcb6c9195a9b0827ffd28113d51f13a)

When the light is red, the middle lamp will display a red countdown.  When the light is green, the middle lamp will display a green countdown.  The middle lamp will be yellow like normal when transitioning from green to red. 

(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fimage.made-in-china.com%2F2f0j00UCHtIjDWJlqP%2FLED-Traffic-Light-Countdown-Timer.jpg&hash=1e0b3e0ed7a650f3ca0a0cd8226371754674d2e9)

There's also a more graphical design.  I don't think this is used anywhere yet, but it's a concept:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fwww.yankodesign.com%2Fimages%2Fdesign_news%2F2009%2F11%2F29%2Feko02.jpg&hash=603ec327b2b30f1308092be0907291c13289fc74)

I think it's actually a pretty cool idea. 

China, the Philippines and Thailand use timers on traffic signals pretty extensively.  There's an older design, with a big obnoxious timer next to the light assembly.
Title: Re: Timers on Traffic Signals
Post by: KEK Inc. on May 04, 2012, 06:14:45 AM
Most municipalities in the west coast have timers in the crosswalk lights now, but they're geared more for pedestrians than motorists. 
Title: Re: Timers on Traffic Signals
Post by: KEK Inc. on May 04, 2012, 06:52:14 AM
Signal timing is relative to traffic circumstances, but I've definitely been stuck at lights for at least 70 seconds here in the U.S.  There's a whole Signal Timing Manual released by the FHWA. 

http://www.signaltiming.com/

Title: Re: Timers on Traffic Signals
Post by: 1995hoo on May 04, 2012, 08:45:44 AM
I like to use the pedestrian timers on the other street to give me a sense for when I can expect the light to turn green. I wish this country had the red/yellow combined cycle you see in much of Europe. Of course the pedestrian timer isn't a perfect substitute due to variations in the phasing at particular intersections (dedicated turn lanes, for example), but it's better than nothing.

Quote from: KEK Inc. on May 04, 2012, 06:52:14 AM
Signal timing is relative to traffic circumstances, but I've definitely been stuck at lights for at least 70 seconds here in the U.S.  There's a whole Signal Timing Manual released by the FHWA. 

http://www.signaltiming.com/

During rush hour, if I hit the traffic light at the exit from my neighborhood right as it turns red for exiting traffic, I sit there for 2.5 minutes (around 150 seconds), more if the people on the other street block the box.
Title: Re: Timers on Traffic Signals
Post by: agentsteel53 on May 04, 2012, 09:57:02 AM
I've been advocating those timers for a while now.

there's an intersection here where I am stuck for a good 90-100 seconds to make a right turn
Title: Re: Timers on Traffic Signals
Post by: mcdonaat on May 04, 2012, 10:00:01 AM
Timers are actually used in Baton Rouge, but usually in the pedestrian walkways. Seems like its meant for the walkers than the drivers, but I use them to determine whether to speed up through the light or stop, whichever is the safest.
Title: Re: Timers on Traffic Signals
Post by: agentsteel53 on May 04, 2012, 10:06:34 AM
Quote from: bulkyorled on May 04, 2012, 07:20:26 AMIt would make no sense to have people wait more than 30 seconds in Los Angeles at major intersections you'd have a huge traffic problem of course.

Wilshire at Santa Monica comes to mind as being about a minute or so.
Title: Re: Timers on Traffic Signals
Post by: mcdonaat on May 04, 2012, 10:10:06 AM
Quote from: agentsteel53 on May 04, 2012, 10:06:34 AM
Quote from: bulkyorled on May 04, 2012, 07:20:26 AMIt would make no sense to have people wait more than 30 seconds in Los Angeles at major intersections you'd have a huge traffic problem of course.

Wilshire at Santa Monica comes to mind as being about a minute or so.
You don't want lights changing too often... the twelve seconds wasted in a yellow changing between two different roads (both ways combined) could be twelve green seconds.
Title: Re: Timers on Traffic Signals
Post by: texaskdog on May 04, 2012, 10:14:13 AM
The dreadfully short green lights in Austin!
Title: Re: Timers on Traffic Signals
Post by: Scott5114 on May 04, 2012, 10:32:45 AM
These are actually prohibited by the US MUTCD for some reason that I can't recall.
Title: Re: Timers on Traffic Signals
Post by: bulkyorled on May 04, 2012, 10:38:32 AM
Quote from: agentsteel53 on May 04, 2012, 10:06:34 AM
Quote from: bulkyorled on May 04, 2012, 07:20:26 AMIt would make no sense to have people wait more than 30 seconds in Los Angeles at major intersections you'd have a huge traffic problem of course.

Wilshire at Santa Monica comes to mind as being about a minute or so.
There's 2 major streets with 2 sides to Santa Monica along with 2 sets of arrows

If you're on the south part of Santa Monica there's at least 2 other lights I can think of that do that. One being when it merges back onto the main part of Santa Monica when it crosses Moreno Dr.
But the wait there is rather pointless at times. Not sure how they'd do it, but they should set up a less wait time for certain times of the day when merging back on. Ive been through there at 3am or so and it still makes you wait an hour for it to go.:banghead:
Title: Re: Timers on Traffic Signals
Post by: english si on May 04, 2012, 01:39:26 PM
They have them across Asia.

I guess there's a problem with a countdown to red/end of green and people rushing to get through before the change - hence the prohibition in MUTCD and the UK TSRGD.
Title: Re: Timers on Traffic Signals
Post by: agentsteel53 on May 04, 2012, 02:08:10 PM
Quote from: english si on May 04, 2012, 01:39:26 PM
I guess there's a problem with a countdown to red/end of green and people rushing to get through before the change - hence the prohibition in MUTCD and the UK TSRGD.

because the average coastal American (LA, New York, the like) driver doesn't already floor it on yellow?
Title: Re: Timers on Traffic Signals
Post by: Central Avenue on May 04, 2012, 04:27:09 PM
Quote from: Scott5114 on May 04, 2012, 10:32:45 AM
These are actually prohibited by the US MUTCD for some reason that I can't recall.
Specifically ones directed at drivers, right? Because the pedestrian ones seem fairly common...
Title: Re: Timers on Traffic Signals
Post by: KEK Inc. on May 04, 2012, 04:45:47 PM
Quote from: english si on May 04, 2012, 01:39:26 PM
They have them across Asia.

I guess there's a problem with a countdown to red/end of green and people rushing to get through before the change - hence the prohibition in MUTCD and the UK TSRGD.
The countdown is for when the green transitions to yellow. 

I can see it being abused for the red countdown, since people will be more than likely to jump the gun when there's 2 seconds left.
Title: Re: Timers on Traffic Signals
Post by: PHLBOS on May 04, 2012, 05:20:27 PM
Quote from: 1995hoo on May 04, 2012, 08:45:44 AMI wish this country had the red/yellow combined cycle you see in much of Europe.
Some older signals in eastern MA still use a steady red & yellow combo to indicate that all vehicular traffic most stop for pedestrian crossings (functions like the current WALK signal).
Title: Re: Timers on Traffic Signals
Post by: kphoger on May 04, 2012, 05:57:02 PM
OK, pedestrian crosswalk timers are not the same as vehicular lane timers.   :rolleyes:
Title: Re: Timers on Traffic Signals
Post by: KEK Inc. on May 04, 2012, 06:09:04 PM
Quote from: kphoger on May 04, 2012, 05:57:02 PM
OK, pedestrian crosswalk timers are not the same as vehicular lane timers.   :rolleyes:
Thank you.
Title: Re: Timers on Traffic Signals
Post by: bulkyorled on May 04, 2012, 06:23:55 PM
Quote from: kphoger on May 04, 2012, 05:57:02 PM
OK, pedestrian crosswalk timers are not the same as vehicular lane timers.   :rolleyes:

No kidding. But they work basically the same. It counts down, time reaches 0 and the light changes.
Title: Re: Timers on Traffic Signals
Post by: PurdueBill on May 04, 2012, 06:35:36 PM
That's where the walk signal timers basically function as de facto green light countdown in a lot of places.  Most of the time they are set so that they strike 0 when the light turns yellow, so if the walk signal timer is visible to traffic, then it provides the same information as a signal countdown would.  I see it a lot--people who have to have noticed this who gun it when they see the countdown is getting close enough to 0 that if they don't speed up, they will get a yellow turning to red so they make sure to get through on yellow.  (If people are watching the pedestrian signals while driving, are they watching other things?  And what if it's an odd signal setup and the light doesn't turn yellow when the timer hits 0?  Like if it turns yellow before that?)
Title: Re: Timers on Traffic Signals
Post by: bulkyorled on May 04, 2012, 06:41:13 PM
That was pretty much what I was saying...

And just by what happens here (not talking about all places of the universe before my post gets all construed), is that all the timers get to 0 and change. I personally have never seen one that reaches 0 and the light doesnt change or it changes before 0. And honestly all it takes is a quick glance to see what the number is. You don't have to stare at it and swerve your car.
Usually the people in the front of the line see the other light reach 0 then they left off their breaks and inch forward anticipating the light is gonna change. Same goes for the driver counters or the crosswalk counters. They work the same, I don't get the problem.
Title: Re: Timers on Traffic Signals
Post by: myosh_tino on May 04, 2012, 06:53:06 PM
Quote from: bulkyorled on May 04, 2012, 06:23:55 PM
Quote from: kphoger on May 04, 2012, 05:57:02 PM
OK, pedestrian crosswalk timers are not the same as vehicular lane timers.   :rolleyes:

No kidding. But they work basically the same. It counts down, time reaches 0 and the light changes.
Not always.  Many of the signals in the San Jose area have countdown pedestrian timers but not all will change when the timer reaches 0.  This is because the signals also rely on detector loops in the pavement that tells the controller to keep the light green to allow additional traffic to pass through the intersection.
Title: Re: Timers on Traffic Signals
Post by: blawp on May 04, 2012, 06:58:51 PM
Bulky, at many intersections the timers hit zero and no light change because the loop sensors are still tripped. This is common in SoCal. Countdown timers wouldn't work here because most of the signals here are fully actuated.
Title: Re: Timers on Traffic Signals
Post by: bulkyorled on May 04, 2012, 07:16:12 PM
Lets put it this way, Los Angeles (the city) works this way in 99% of the cases.  :banghead:
Title: Re: Timers on Traffic Signals
Post by: KEK Inc. on May 04, 2012, 08:09:10 PM
Quote from: blawp on May 04, 2012, 06:58:51 PM
Bulky, at many intersections the timers hit zero and no light change because the loop sensors are still tripped. This is common in SoCal. Countdown timers wouldn't work here because most of the signals here are fully actuated.

If the light relies on traffic detection, then the timer would be blank until the 10 seconds when the light WILL change.

The only thing that will alter it is an emergency vehicle or power failure. 
Title: Re: Timers on Traffic Signals
Post by: myosh_tino on May 04, 2012, 11:52:01 PM
Quote from: KEK Inc. on May 04, 2012, 08:09:10 PM
Quote from: blawp on May 04, 2012, 06:58:51 PM
Bulky, at many intersections the timers hit zero and no light change because the loop sensors are still tripped. This is common in SoCal. Countdown timers wouldn't work here because most of the signals here are fully actuated.

If the light relies on traffic detection, then the timer would be blank until the 10 seconds when the light WILL change.

The only thing that will alter it is an emergency vehicle or power failure. 
That's still not right.  If someone triggers the pedestrian signal, then there's a set minimum time the light will remain green to allow the person to cross the street.  When countdown timers and detection loops are both used, a signal will remain green for *at least* the amount of time on the countdown timer but the signal may stay green if additional traffic is detected by the loops.
Title: Re: Timers on Traffic Signals
Post by: KEK Inc. on May 05, 2012, 10:13:09 AM
The countdown would only initiate once the light starts ignoring additional traffic and pedestrians or there's no activity in the other directions. 

The detection loops are mainly used to cycle the light faster if there's no traffic.  If there's heavy traffic, they're on a timer.
Title: Re: Timers on Traffic Signals
Post by: kphoger on May 05, 2012, 12:52:49 PM
In Wichita, I can think a few intersections where stoplights operate on timers, yet still don't change colors when the ped countdown hits zero.  I actually get annoyed while driving, because I use the ped countdown to tell me if I should slow down or not (expecting a red or green light upon arriving at the intersection);  I brake, preparing to stop, and then the light is still green.  D'oh!  If only I could remember excatly which intersections are like that every time I drive.
Title: Re: Timers on Traffic Signals
Post by: blawp on May 06, 2012, 02:31:25 AM
KEK, what if someone trips the "10-second" countdown you mention and then decides to make a right on red? The countdown clock goes blank?
Title: Re: Timers on Traffic Signals
Post by: KEK Inc. on May 06, 2012, 07:47:01 AM
Quote from: blawp on May 06, 2012, 02:31:25 AM
KEK, what if someone trips the "10-second" countdown you mention and then decides to make a right on red? The countdown clock goes blank?

The light would commit to the 10 second countdown.  It would ignore pedestrian requests and traffic from other directions. 
Title: Re: Timers on Traffic Signals
Post by: Alps on May 06, 2012, 04:12:45 PM
Quote from: KEK Inc. on May 06, 2012, 07:47:01 AM
Quote from: blawp on May 06, 2012, 02:31:25 AM
KEK, what if someone trips the "10-second" countdown you mention and then decides to make a right on red? The countdown clock goes blank?

The light would commit to the 10 second countdown.  It would ignore pedestrian requests and traffic from other directions. 
Ideally, when it gets to 0 and the call has disappeared, the signal should reset without ever cycling through. I've also seen the peds stay on DW while the through light stays green until the next call.
Title: Re: Timers on Traffic Signals
Post by: roadfro on May 06, 2012, 04:58:38 PM
The only way red or green countdowns for vehicles will work is if the signal runs fixed time settings, as the time to the beginning or end of a phase is always known. If any type of vehicle detection is used and the signal is in an actuated mode, the green or red settings vary dynamically within the phase depending on vehicle arrivals. Once the detectors stop sensing the presence of vehicles there is usually less than 6 seconds before the light changes (depending on travel speed and spacing of upstream detection--could be more but is frequently less). A vehicle countdown at this point is not really useful.

There is also the matter of drivers speeding up to make the light, or jumping the gun on a changing signal. I believe this was the main concern FHWA had in not allowing these displays, but the operational aspect of green extension in signal controllers is what makes the countdown less reliable.

Quote from: KEK Inc. on May 05, 2012, 10:13:09 AM
The countdown would only initiate once the light starts ignoring additional traffic and pedestrians or there's no activity in the other directions. 

The detection loops are mainly used to cycle the light faster if there's no traffic.  If there's heavy traffic, they're on a timer.

If there's heavy traffic and detection is used, the light isn't necessarily on a "timer" but it's more likely that the green time reaches the maximum green setting in the controller and is forced to change phases. This is one possibility where a countdown might work, but again cannot be reliably predicted because of random traffic arrivals.
Title: Re: Timers on Traffic Signals
Post by: 1995hoo on May 07, 2012, 09:44:00 AM
There are a number of them around here that reach 0 and the light doesn't immediately turn yellow. Several of those involve a lagging left-turn cycle, but not all of them. Some of them just seem to be random exceptions.
Title: Re: Timers on Traffic Signals
Post by: hm insulators on May 08, 2012, 02:56:27 PM
Quote from: bulkyorled on May 04, 2012, 06:01:19 AM
I like the large timers especially the one in the 2nd pic since theyre more geared for the driver to look at.
In Los Angeles ALL the lights have timers now. They're on the crosswalks but they always go no matter if someone crossed the street or not, generally lasting from 8-30 seconds preceded by the Walk symbol which usually will last an aditional 8-10 seconds, sometimes a bit more but not usually. And most of the suburbs have them too. The only city that I rarely see them in is Glendale, and then up a bit in LA County in the cities of Lancaster & Palmdale, however those 2 cities seem to be getting counters now as they replace old light setups.

The Phoenix area has these, too.
Title: Re: Timers on Traffic Signals
Post by: agentsteel53 on May 08, 2012, 03:04:40 PM
Quote from: myosh_tino on May 04, 2012, 06:53:06 PM
Not always.  Many of the signals in the San Jose area have countdown pedestrian timers but not all will change when the timer reaches 0.  This is because the signals also rely on detector loops in the pavement that tells the controller to keep the light green to allow additional traffic to pass through the intersection.

does the opposite exist?  i.e. a light turning yellow, then red, while the pedestrian counter keeps going?

the only way I could imagine this is if there were a segue into an all-pedestrian phase, but I cannot think of a situation where it would be good design to do this.
Title: Re: Timers on Traffic Signals
Post by: myosh_tino on May 08, 2012, 03:21:18 PM
Quote from: agentsteel53 on May 08, 2012, 03:04:40 PM
Quote from: myosh_tino on May 04, 2012, 06:53:06 PM
Not always.  Many of the signals in the San Jose area have countdown pedestrian timers but not all will change when the timer reaches 0.  This is because the signals also rely on detector loops in the pavement that tells the controller to keep the light green to allow additional traffic to pass through the intersection.

does the opposite exist?  i.e. a light turning yellow, then red, while the pedestrian counter keeps going?

the only way I could imagine this is if there were a segue into an all-pedestrian phase, but I cannot think of a situation where it would be good design to do this.
I have not seen a pedestrian signal behave like that but the only way one would exist is if, as you said, an all-pedestrian phase were coming up.
Title: Re: Timers on Traffic Signals
Post by: agentsteel53 on May 08, 2012, 03:24:54 PM
Quote from: myosh_tino on May 08, 2012, 03:21:18 PM
I have not seen a pedestrian signal behave like that but the only way one would exist is if, as you said, an all-pedestrian phase were coming up.

I would say it is in fact not just a bad idea, but a terrible one, given that drivers use the pedestrian countdown to give themselves a worst case timing on when the green goes away.  a "surprise yellow" could be disastrous.
Title: Re: Timers on Traffic Signals
Post by: myosh_tino on May 08, 2012, 03:33:33 PM
Quote from: agentsteel53 on May 08, 2012, 03:24:54 PM
Quote from: myosh_tino on May 08, 2012, 03:21:18 PM
I have not seen a pedestrian signal behave like that but the only way one would exist is if, as you said, an all-pedestrian phase were coming up.

I would say it is in fact not just a bad idea, but a terrible one, given that drivers use the pedestrian countdown to give themselves a worst case timing on when the green goes away.  a "surprise yellow" could be disastrous.
What is you general opinion on an all-pedestrian phase?  Thinking about how traffic flows (or doesn't) in San Francisco, I'm wondering if adding an all-pedestrian phase would improve traffic flow by allowing cars turning right to not have to worry about pedestrians in the crosswalk.
Title: Re: Timers on Traffic Signals
Post by: agentsteel53 on May 08, 2012, 03:42:56 PM
Quote from: myosh_tino on May 08, 2012, 03:33:33 PM
What is you general opinion on an all-pedestrian phase?  Thinking about how traffic flows (or doesn't) in San Francisco, I'm wondering if adding an all-pedestrian phase would improve traffic flow by allowing cars turning right to not have to worry about pedestrians in the crosswalk.

I haven't had all that much experience with it.

in Los Angeles the pedestrian flow can get really bad for turning traffic.  since LA is installing a lot of protected lefts, I would imagine the solution would be to install corresponding protected rights as well.  i.e if eastbound is turning northbound, then at the same time southbound could be allowed to turn westbound.

but since SF doesn't seem to be as universally in the protected-left business, that might not be the solution there.  hell, half of SF's traffic lights are side-mounted, so not only would you need new signals for protected left, but you'd need new mast arms!
Title: Re: Timers on Traffic Signals
Post by: 1995hoo on May 08, 2012, 03:57:34 PM
Quote from: myosh_tino on May 08, 2012, 03:33:33 PM
Quote from: agentsteel53 on May 08, 2012, 03:24:54 PM
Quote from: myosh_tino on May 08, 2012, 03:21:18 PM
I have not seen a pedestrian signal behave like that but the only way one would exist is if, as you said, an all-pedestrian phase were coming up.

I would say it is in fact not just a bad idea, but a terrible one, given that drivers use the pedestrian countdown to give themselves a worst case timing on when the green goes away.  a "surprise yellow" could be disastrous.
What is you general opinion on an all-pedestrian phase?  Thinking about how traffic flows (or doesn't) in San Francisco, I'm wondering if adding an all-pedestrian phase would improve traffic flow by allowing cars turning right to not have to worry about pedestrians in the crosswalk.

DC has one intersection with an all-pedestrian phase, the intersection of 7th & H Streets NW near the Verizon Center and Chinatown. An entrance to a subway stop is located on the southeast corner of the intersection and it's a high-pedestrian area pretty much most of the time due to a high concentration of restaurants and bars. When I'm a pedestrian I like the all-way phasing.

But I never drive through that intersection if I can avoid it because of the way DC implemented it. A normal "Barnes Dance" phasing allows crossing only during the all-way phase. That way drivers are free to turn right or left, or go straight, without encountering pedestrians (who in return get a shorter crossing because they can go diagonally and cross just once instead of twice). But DC decided that most pedestrians in the DC area cannot be trusted to wait their turn before crossing on a "Walk" signal (that's probably true because 95% of them think they can walk whenever and wherever they want) and that if the all-way pedestrian phase were the only time at which a "Walk" signal were displayed, pedestrians would get tired of waiting and would walk against the light (probably a valid assumption because they do that everywhere else). So instead of prohibiting crossing outside of the "all-way pedestrian" phase, DC instead prohibited motorists from making any turns (right or left) at that intersection. The theory is that by prohibiting turns you eliminate the conflict between turning drivers and pedestrians, and you also eliminate the delays when a turning car blocks the way for other cars. Problem is, many drivers ignore the no-turns restriction (and many don't seem aware of it at all because the signs aren't really prominent enough in that very busy area), and I suppose nobody should really be surprised at this because H Street is a fairly important cross-town route ever since Bill Clinton let the Secret Service close a section of Pennsylvania Avenue in 1995.
Title: Re: Timers on Traffic Signals
Post by: agentsteel53 on May 08, 2012, 04:03:03 PM
Quote from: 1995hoo on May 08, 2012, 03:57:34 PM

But I never drive through that intersection if I can avoid it because of the way DC implemented it.
[snip]

are you saying there are only three phases?

north-south, no turns
east-west, no turns
pedestrians

rinse and repeat?
Title: Re: Timers on Traffic Signals
Post by: 1995hoo on May 08, 2012, 04:18:47 PM
Quote from: agentsteel53 on May 08, 2012, 04:03:03 PM
Quote from: 1995hoo on May 08, 2012, 03:57:34 PM

But I never drive through that intersection if I can avoid it because of the way DC implemented it.
[snip]

are you saying there are only three phases?

north-south, no turns
east-west, no turns
pedestrians

rinse and repeat?


Sort of, with a clarification to underscore how the pedestrian signals work. 7th Street runs north/south and H Street runs east/west. So this is what it does:

(a) 7th Street traffic has a green light and pedestrians crossing H Street get "Walk" signals (for conventional straight-across crossing only). No turns allowed.

(b) H Street traffic has a green light and pedestrians crossing 7th Street get "Walk" signals (again for straight-across crossing only). No turns allowed.

(c) All-way red for drivers and the pedestrians get "Walk" signals for both straight-across and diagonal crossing. No turns allowed.

After (c) it goes back to (a) again.

Turns are occasionally allowed when one of the streets is closed, of course; 7th is sometimes closed south of H after a game or a concert and H is periodically closed east of 7th if there's some sort of Chinese festival going on (the name "Chinatown" isn't too accurate anymore and "Chinablock" might be more accurate to refer to that one block).
Title: Re: Timers on Traffic Signals
Post by: agentsteel53 on May 08, 2012, 04:24:10 PM
that just sounds like silly design overall.

San Francisco also has some intersections with particular turns prohibited.  Park Presidio at Fulton comes to mind.  In order to take a left turn, one has to turn right onto a small anonymous residential street, turn left onto another, and then turn left onto Fulton - a completely unprotected left turning onto four lanes of boulevard traffic.

this is pretty badly signed, so you just imagine your GPS is smoking something powerful when it suggests that ... but that is, indeed, the correct way to do things.
Title: Re: Timers on Traffic Signals
Post by: NE2 on May 08, 2012, 05:01:30 PM
Quote from: agentsteel53 on May 08, 2012, 04:24:10 PM
San Francisco also has some intersections with particular turns prohibited.  Park Presidio at Fulton comes to mind.  In order to take a left turn, one has to turn right onto a small anonymous residential street, turn left onto another, and then turn left onto Fulton - a completely unprotected left turning onto four lanes of boulevard traffic.

this is pretty badly signed, so you just imagine your GPS is smoking something powerful when it suggests that ... but that is, indeed, the correct way to do things.
Totally jughandular, man.
Title: Re: Timers on Traffic Signals
Post by: agentsteel53 on May 08, 2012, 05:06:42 PM
Quote from: NE2 on May 08, 2012, 05:01:30 PM

Totally jughandular, man.

does that count as a jughandle?

http://en.wikipedia.org/wiki/Jughandle

there are three types mentioned there, and none require three explicit turns.  at least one of the turns is smoothed out (Type A) into a ramp, or both are (Type B) or the jughandle is in reverse with a single ramp (Type C).
Title: Re: Timers on Traffic Signals
Post by: NE2 on May 08, 2012, 05:22:26 PM
I'd count it, since it simply replaces the ramps with existing streets. No different from an interchange that uses streets.
Title: Re: Timers on Traffic Signals
Post by: 1995hoo on May 08, 2012, 05:42:02 PM
Quote from: agentsteel53 on May 08, 2012, 04:24:10 PM
that just sounds like silly design overall.

San Francisco also has some intersections with particular turns prohibited.  Park Presidio at Fulton comes to mind.  In order to take a left turn, one has to turn right onto a small anonymous residential street, turn left onto another, and then turn left onto Fulton - a completely unprotected left turning onto four lanes of boulevard traffic.

this is pretty badly signed, so you just imagine your GPS is smoking something powerful when it suggests that ... but that is, indeed, the correct way to do things.

I understand prohibiting some turns, particularly left turns in an urban area where there are no turn lanes. I probably should have mentioned that the 7th & H intersection I mentioned earlier is of that sort (no turn lanes for either right or left turns) and so banning left turns even with a traditional "Barnes Dance" configuration would have made sense. But banning right turns is a nuisance.

Come to think of it, I wonder how many people seeking to turn there are being guided by sat-navs that were programmed prior to the "No Turns" restriction, which only went up within the past two or three years.
Title: Re: Timers on Traffic Signals
Post by: kphoger on May 08, 2012, 07:03:46 PM
Quote from: agentsteel53 on May 08, 2012, 03:04:40 PM
Quote from: myosh_tino on May 04, 2012, 06:53:06 PM
Not always.  Many of the signals in the San Jose area have countdown pedestrian timers but not all will change when the timer reaches 0.  This is because the signals also rely on detector loops in the pavement that tells the controller to keep the light green to allow additional traffic to pass through the intersection.

does the opposite exist?  i.e. a light turning yellow, then red, while the pedestrian counter keeps going?

the only way I could imagine this is if there were a segue into an all-pedestrian phase, but I cannot think of a situation where it would be good design to do this.

I've seen a signal that had the WALK signal on during red lights and DON'T WALK during green lights.  But, then, that was just a signal not working properly.  :-/
Title: Re: Timers on Traffic Signals
Post by: Alps on May 08, 2012, 07:32:48 PM
Quote from: agentsteel53 on May 08, 2012, 03:04:40 PM
Quote from: myosh_tino on May 04, 2012, 06:53:06 PM
Not always.  Many of the signals in the San Jose area have countdown pedestrian timers but not all will change when the timer reaches 0.  This is because the signals also rely on detector loops in the pavement that tells the controller to keep the light green to allow additional traffic to pass through the intersection.

does the opposite exist?  i.e. a light turning yellow, then red, while the pedestrian counter keeps going?

the only way I could imagine this is if there were a segue into an all-pedestrian phase, but I cannot think of a situation where it would be good design to do this.
I've seen older counters reach 0 at the red light, but that's been written out of the MUTCD and agencies are now converting to the new standard. While on the topic of the MUTCD, I'll just point out that drivers are explicitly not supposed to rely on pedestrian timers. I know they do anyway, but my point is that design should not account for that.
Title: Re: Timers on Traffic Signals
Post by: agentsteel53 on May 08, 2012, 07:39:15 PM
Quote from: Steve on May 08, 2012, 07:32:48 PMWhile on the topic of the MUTCD, I'll just point out that drivers are explicitly not supposed to rely on pedestrian timers. I know they do anyway, but my point is that design should not account for that.

how does the general driving populace know that?  countdown timers certainly weren't covered when I took driver ed, so I'd be tempted to go with my intuition...
Title: Re: Timers on Traffic Signals
Post by: Alps on May 08, 2012, 07:42:41 PM
Quote from: agentsteel53 on May 08, 2012, 07:39:15 PM
Quote from: Steve on May 08, 2012, 07:32:48 PMWhile on the topic of the MUTCD, I'll just point out that drivers are explicitly not supposed to rely on pedestrian timers. I know they do anyway, but my point is that design should not account for that.

how does the general driving populace know that?  countdown timers certainly weren't covered when I took driver ed, so I'd be tempted to go with my intuition...
That's why I'm limiting my comment to the design field. Don't design countdown timers for drivers to peep at.
Title: Re: Timers on Traffic Signals
Post by: roadfro on May 09, 2012, 05:50:44 AM
Quote from: Steve on May 08, 2012, 07:32:48 PM
I've seen older counters reach 0 at the red light, but that's been written out of the MUTCD and agencies are now converting to the new standard.

That's still allowable in the 2009 MUTCD--see Figure 4E-2. There are a number of ways the countdown can work out as long as the pedestrian clearance time finishes before opposing traffic is released.
Title: Re: Timers on Traffic Signals
Post by: Alps on May 11, 2012, 08:23:31 PM
Quote from: roadfro on May 09, 2012, 05:50:44 AM
Quote from: Steve on May 08, 2012, 07:32:48 PM
I've seen older counters reach 0 at the red light, but that's been written out of the MUTCD and agencies are now converting to the new standard.

That's still allowable in the 2009 MUTCD--see Figure 4E-2. There are a number of ways the countdown can work out as long as the pedestrian clearance time finishes before opposing traffic is released.
And yet agencies are still converting to 0 on the yellow.
Title: Re: Timers on Traffic Signals
Post by: roadman65 on August 03, 2012, 04:27:24 AM
The timers should be used, I think, at intersections that have cameras.  I often worry about passing through these intersections, cause one day the light will turn at a time when I am too close to stop for the signal while being too far away from the stop bar to actually make it across it and the sensor that activates the mechanism.   

If I see it is getting near 0, providing the timer is set to turn at that point, I would slow down so that I can be in a safe mode to stop in time for the stop line where I do not need to run nor screech to a stop.
Title: Re: Timers on Traffic Signals
Post by: jeffandnicole on August 03, 2012, 08:30:46 AM
Quote from: roadfro on May 09, 2012, 05:50:44 AM
Quote from: Steve on May 08, 2012, 07:32:48 PM
I've seen older counters reach 0 at the red light, but that's been written out of the MUTCD and agencies are now converting to the new standard.

That's still allowable in the 2009 MUTCD--see Figure 4E-2. There are a number of ways the countdown can work out as long as the pedestrian clearance time finishes before opposing traffic is released.


It appears that Delaware is using all 5 options at various intersections!  Maybe they're testing out different options.  Personally, IMO, I dislike the option where the countdown timer goes to 0 just as the light hits red.  The yellow light should be used to clear the intersection of traffic, and not to be encouraged to allow pedestrians to complete their stroll across the roadway.

I've also noticed Delaware now has a whole pedestrian detour set up when a section (and in many cases, a very small section) of sidewalk is under construction.  They use small orange Detour signs with a small pedestrian on it (ie: http://mutcd.fhwa.dot.gov/htm/2009/part6/fig6f_05_longdesc.htm , M4-9b ).  The detour route starts at the previous intersection and continues to the next intersection.  In many cases, they use a barrier to try to prevent people from continuing on the sidewalk.  And when they are on the detour route, additional detour signs are posted to show pedestrians that they should continue on the sidewalk until the next intersection.

Signage overkill?  Oh...yeah...
Title: Re: Timers on Traffic Signals
Post by: roadman65 on August 05, 2012, 07:16:01 AM
Quote from: jeffandnicole on August 03, 2012, 08:30:46 AM
Quote from: roadfro on May 09, 2012, 05:50:44 AM
Quote from: Steve on May 08, 2012, 07:32:48 PM
I've seen older counters reach 0 at the red light, but that's been written out of the MUTCD and agencies are now converting to the new standard.

That's still allowable in the 2009 MUTCD--see Figure 4E-2. There are a number of ways the countdown can work out as long as the pedestrian clearance time finishes before opposing traffic is released.


It appears that Delaware is using all 5 options at various intersections!  Maybe they're testing out different options.  Personally, IMO, I dislike the option where the countdown timer goes to 0 just as the light hits red.  The yellow light should be used to clear the intersection of traffic, and not to be encouraged to allow pedestrians to complete their stroll across the roadway.

I've also noticed Delaware now has a whole pedestrian detour set up when a section (and in many cases, a very small section) of sidewalk is under construction.  They use small orange Detour signs with a small pedestrian on it (ie: http://mutcd.fhwa.dot.gov/htm/2009/part6/fig6f_05_longdesc.htm , M4-9b ).  The detour route starts at the previous intersection and continues to the next intersection.  In many cases, they use a barrier to try to prevent people from continuing on the sidewalk.  And when they are on the detour route, additional detour signs are posted to show pedestrians that they should continue on the sidewalk until the next intersection.

Signage overkill?  Oh...yeah...

Florida has the same thing when sidewalks are partially closed.  Many people ignore them, of course, and walk on the street in traffic in the same manner people now do not use the crosswalks either.  Many will cross even 10 feet away from the crosswalk and even rather walk around stopped cars at a signal then walk straight across.

I do not think there is anything to worry as police have forgotten that jay walking is an citeable offense so they will not do anything here either.
Title: Re: Timers on Traffic Signals
Post by: NE2 on August 05, 2012, 07:38:43 AM
Quote from: roadman65 on August 05, 2012, 07:16:01 AM
I do not think there is anything to worry as police have forgotten that jay walking is an citeable offense so they will not do anything here either.
Please look up exactly what "jaywalking" is.
Title: Re: Timers on Traffic Signals
Post by: KEK Inc. on August 05, 2012, 04:22:24 PM
Can we stay on topic guys?  As I said over and over again, I'm not referring to pedestrian crossings.    :pan:   If you want to talk about that, please feel free to make a separate thread...   :spin: