Stoplights with vehicle detectors

[Scott5114]

Am I the only one that hates these?

Maybe it's because I'm nocturnal (I head in to work at 12:30 and tend to keep the same sleep schedule on my days off) so I do a lot of driving at night. That means I encounter a lot of stoplights that default to "green the main street and change when there's a car needing to use the intersection" overnight.

The problem with this is most exaggerated when I'm using OK 9. This is an expressway around the south side of Norman that has a 50 MPH speed limit with stoplights. It's much better than having nothing at all and is nearly always the best way to get from eastern Norman to I-35. The problem is the lights are set up with the vehicle detectors as described above.

I'll generally be cruising west at 50 MPH around half past midnight, on the way to work, where of course damn near everything in town is operating at LOS A. The problem comes when someone will inevitably want to perform an EB-to-NB movement as I approach the intersection. So I have to come to a complete stop because the stoplight was triggered by the  car in the left turn bay, giving them the green and me red. When, had it just been set to permissive left, I could have continued along at 50 and they could have just gone after me (they were already at a stop, after all). Even worse is when someone wants to make a right turn onto either direction of the road I'm on. I have to come to a stop when the light didn't even need to change; they could have performed a right on red. Hell, I probably would see them wanting to do so and get into the left lane to make it easier for them. And when they want to turn right to go EB when I'm going WB? Why do I have to stop? It seems a bit perverse to have to stop in these situations; I am pretty much being forced to yield right of way to a single non-mainline driver for no real reason.

OK 9 has it worse than most by virtue of being an expressway with a 50 MPH speed limit, but it's just as bad on a city street. There is one intersection in particular that comes to mind that is half of a diamond interchange. Because a state highway goes west from this interchange, the vast majority of traffic from the SB interstate is turning right. But the stoplight still triggers to give them the green, even though they nearly always want to turn right, so the EB and WB state highway is stopped needlessly, leading to backups. Rather annoying.

[KEK Inc.]

I love them.  I hate the timers.  For the left turn one, it should have allowed straight traffic to go too, but that depends on the traffic engineer, I suppose. 

My city's downtown shuts off all of the lights to flashing red/yellow at 10:30 PM, so every intersection is a stop sign unless it's a major road with a flashing yellow.

[Scott5114]

Timers are suboptimal too. Anything to prevent 50 MPH traffic from having to come to a complete stop just because some asshole wants to turn left.

[realjd]

Intersections with vehicle sensors are MUCH preferred to ones without. It sounds like they just need to flip them to flashing yellow/red at night in your case.

[deathtopumpkins]

I love sensors during the day when there is traffic, but, like Scott, despise them at night. I usually get off work around 10 PM, and my neighborhood quiets down quickly at night. I can't think of a single intersection that wouldn't be perfectly fine with just flashers at night.

[Scott5114]

Yes, flashers work pretty well. I loved cruising around Springfield. MO late at night. Plus, the flashing lights add some atmosphere to the night. Unfortunately, OK seems to have never heard of the concept.

[vdeane]

I love sensors during the day when there is traffic, but, like Scott, despise them at night. I usually get off work around 10 PM, and my neighborhood quiets down quickly at night. I can't think of a single intersection that wouldn't be perfectly fine with just flashers at night.

Don't drive in New York then.  Most signals here have vehicle sensors, but only at night.  During the day we use timers.

[architect77]

Without sensors, you could have a situation like in Raleigh, NC. Lights are timed for normal traffic levels, and overnight you can sit for 3-4 minutes waiting to turn at an intersection without another car in sight.

They are in the process of a 5-year, citywide, signal timing and upgrade project that might include sensors, i'm not sure.

[jjakucyk]

Cincinnati is all over the place on this one.  There's a lot of legacy intersections that are just on timers, which can be annoying at night since the cycles don't usually change.  There's lots of intersections that go to flashing at night, and some that don't.  Some intersections only have sensors for the left turn pocket, or only for the side street.  However, I will say that when they do signalized intersections at side streets here, they usually do them right.  There's one particular intersection nearby where I see people on the side street who are just doing a right turn on red.  If they have to sit there too long, the main street will get stopped and they get a green light.  However, if they make the turn on red the controller will reset and clear out the request.  Many times you can even watch it happen.  The pedestrian crossing signals (most of which around here do not require pushbutton activation) will start flashing "don't walk" but then the car turns and they go right back to "walk" again.  I'm surprised that's not done more often. 

[Bryant5493]

I like vehicle detector intersections. They're being phased in here in Metro Atlanta. There still are quite a few, of course, without them. One of the "smartest" intersections I've encountered is S.R. 139/Riverdale Road and Phoenix Boulevard/Forest Parkway, just south of the Atlanta Airport. It's efficient in keeping traffic moving, especially at night.


Be well,

Bryant

[roadfro]

Scott:  It sounds like they need to adjust the detection and/or cycle at many of those intersections you encounter.

jjackucyk:  The feature of the pedestrian crossing signals you're describing isn't necessarily the controller clearing out a vehicle activation. Most signal controllers have a feature called "rest in walk", where the pedestrian signal defaults to the walking man if there's no conflicting phases. The walking man only lasts for a set amount of time (which generally cannot be overridden), so it is automatically followed by flashing don't walk. If the adjacent vehicle phase is still green at the end of the FDW time, the pedestrian signal goes back to the walk signal.

[wandering drive]

Scott:  It sounds like they need to adjust the detection and/or cycle at many of those intersections you encounter.

jjackucyk:  The feature of the pedestrian crossing signals you're describing isn't necessarily the controller clearing out a vehicle activation. Most signal controllers have a feature called "rest in walk", where the pedestrian signal defaults to the walking man if there's no conflicting phases. The walking man only lasts for a set amount of time (which generally cannot be overridden), so it is automatically followed by flashing don't walk. If the adjacent vehicle phase is still green at the end of the FDW time, the pedestrian signal goes back to the walk signal.

I adore those kinds of lights.  Keeps traffic moving on the main street, but also lets drivers know that the light might change.  Only ones I've seen are on East Washington Avenue on the east side of Madison, WI.

Related: The lights around downtown Owatonna, MN take "vehicle detector" to the next level.  The light at Rose St and Hoffman Dr (and maybe others as well, I'm not sure) have the standard "Push button to activate 'Walk' sign" mechanisms to go across the busier Hoffman Dr, but instead of just waiting for the next cycle to go to "walk," Hoffman Dr goes to yellow immediately.  I can just imagine some unscrupulous kids or an a-hole cop sitting on the corner at night waiting for some car to pull up so they can hit the button and watch the oncoming driver panic.

[jjakucyk]

jjackucyk:  The feature of the pedestrian crossing signals you're describing isn't necessarily the controller clearing out a vehicle activation. Most signal controllers have a feature called "rest in walk", where the pedestrian signal defaults to the walking man if there's no conflicting phases. The walking man only lasts for a set amount of time (which generally cannot be overridden), so it is automatically followed by flashing don't walk. If the adjacent vehicle phase is still green at the end of the FDW time, the pedestrian signal goes back to the walk signal.

Perhaps, but I've never seen it happen without someone executing a right on red from the side street first. 

[WillWeaverRVA]

Richmond has timed traffic lights. It's pretty terrible sitting at the traffic light at Broad Street (US 33/250) and Boulevard (VA 161) for about 5 minutes at 1am with virtually no traffic on the road.

Is there not some sort of hybrid setup that can switch from timed cycles during periods of peak traffic flow (based on traffic counts/AADT) to sensor-based ones at other times? Is this even possible?

[andytom]

Is there not some sort of hybrid setup that can switch from timed cycles during periods of peak traffic flow (based on traffic counts/AADT) to sensor-based ones at other times? Is this even possible?

They use something like this in Beaverton, OR.  During the day, the signal runs on a timer/sensor system (stays green for the primary road for a minimum time then switches when the side road sensor is activated, stays green for the side road until the sensor is not activated up to a maximum amount of time).  Overnight, they switch to sensor only.  You can easily tell which signals have broken sensors because the signal is constantly changing at 2am (if the city would only send someone out to look).

--Andy

[DollarBill]

I prefer sensor signals. Time signals are ok during the day but get really annoying at night in low traffic areas. I dont see why many sensor signals arent set to switch to flashing red or red/yellow at night.

[mightyace]

Is there not some sort of hybrid setup that can switch from timed cycles during periods of peak traffic flow (based on traffic counts/AADT) to sensor-based ones at other times? Is this even possible?

Nashville uses a setup on lesser roads where it's sensor driven from early morning until 11pm or midnight then it's on flasher.  The rest that are on sensors seem to be so 24x7.

[architect77]

After spending the last 10 years in NYC, I was shocked when officials admitted that the buttons "Push to activate Walk" located throughout the city are fake and not connected to anything. They only provide psychological gratification for the user, in that they've done all they can to speed up the process.

While funny, I truly felt deceived as a New Yorker.

[Alps]

After spending the last 10 years in NYC, I was shocked when officials admitted that the buttons "Push to activate Walk" located throughout the city are fake and not connected to anything. They only provide psychological gratification for the user, in that they've done all they can to speed up the process.

While funny, I truly felt deceived as a New Yorker.

Yeah, the lights operate on a fixed time and the Walk signal always appears.  I do know there are many locations where the only difference between pushing the button or not is whether you see a hand or a little man, but the timing doesn't change.

[SSOWorld]

There's one intersection in Wausau, WI where if nobody's there all the directions have red

[wandering drive]

After spending the last 10 years in NYC, I was shocked when officials admitted that the buttons "Push to activate Walk" located throughout the city are fake and not connected to anything. They only provide psychological gratification for the user, in that they've done all they can to speed up the process.

While funny, I truly felt deceived as a New Yorker.

Was that always the case, though?  There are some in Minneapolis that I know used to work but they have been switched to automatically go "walk."  No point in removing the buttons, of course.

[jjakucyk]

Every place is different I guess.  Here in Cincinnati most of the ped signals go to walk automatically with the green vehicular signal, so there's no buttons at those locations.  At more complicated intersections, or ones with high volumes of vehicular traffic and little pedestrian activity, then you have to push a button.  I'm not aware of any fake buttons around here. 

[Troubleshooter]

There are several competing wrinkles in the operation of signals at night:

- A signal can be set up to rest in several different ways:
--- Rest with the artery street green and walk
--- Rest with the artery street green and the ped signal changing  to keep coordination
--- Rest in artery green and don't walk (ped actuated)
--- Rest with the last phase used green
--- Rest in all red (causes unnecessary stops if the signal decides to rest in front of you)
--- Don't rest, but maintain operation for coordination

The problem happens when the signal is resting, and two cars approach the intersection. Whichever car actuates the detector first takes the signal out of rest, changing the light to that phase.

Another problem at night is yellow trap. A signal with protected/permissive turns might be resting when several cars approach from opposite directions with slightly different timings. Cars arriving first take the signal out of rest, and can cause it to change from artery rest to left turn in one direction with the overlapping thru movement also green. A car in the slightly later group coming from the opposite direction might turn left on the yellow. Its driver does not know the opposite signal is still green, and turns in front of live traffic.

Those signals in NY used to have exclusive pedestrian phases. When they were switched over to walk overlapping green, the buttons were left in place.

Many signal systems in downtown areas maintain operation at night, so the driver on the thru street has coordination. He gets greens all the way down the street.