AARoads Forum

National Boards => General Highway Talk => Traffic Control => Topic started by: XamotCGC on September 26, 2022, 11:00:05 PM

Title: Strange Stop Light question.
Post by: XamotCGC on September 26, 2022, 11:00:05 PM
What's the purpose of the extra Stop Light on the silver pole? They added it just recently.

https://www.google.com/maps/@37.5754236,-85.2352742,3a,16.2y,261.41h,90.4t/data=!3m6!1e1!3m4!1s5CGmJXSi9mhSAqMaY-akig!2e0!7i16384!8i8192?hl=en (https://www.google.com/maps/@37.5754236,-85.2352742,3a,16.2y,261.41h,90.4t/data=!3m6!1e1!3m4!1s5CGmJXSi9mhSAqMaY-akig!2e0!7i16384!8i8192?hl=en)
Title: Re: Strange Stop Light question.
Post by: kirbykart on September 27, 2022, 09:34:31 AM
Yeah that seems pretty useless. Usually those extra lights appear at busy urban junctions, but they're really not even necessary there.
Title: Re: Strange Stop Light question.
Post by: kphoger on September 27, 2022, 09:42:14 AM
I assume it's because the existing overhead signals were found to be insufficiently visible to all traffic.  Perhaps there was an accident, and one of the parties stated that he couldn't see the red light because it was blocked by a truck or something.

Quote from: U.S. Department of Transportation, Federal Highway Administration
Manual on Uniform Traffic Control Devices, Millennium Edition

Part 4 Highway Traffic Signals

Chapter 4D Traffic Control Signal Features

4D.15 Size, Number, and Location of Signal Faces by Approach


Supplemental signal faces should be used if engineering judgment has shown that they are needed to achieve intersection visibility both in advance and immediately before the signalized location. If supplemental signal faces are used, they should be located to provide optimum visibility for the movement to be controlled.
Title: Re: Strange Stop Light question.
Post by: Hobart on September 27, 2022, 10:08:15 AM
It is possible that there is a lot of truck traffic in that direction, or situations where the overhead signals are blocked from thru traffic. I know many jurisdictions, including Alaska, make a far-right ground-level signal a requirement for that reason. It's only in one direction though, which makes me unsure if this was their justification here.

I think it's a visibility thing. The approach with the ground-level signal is the first approach leading into town for US-68, so they might have put in the extra head to draw more attention to the signal. It's also worth mentioning that the next signal further into town, and the signals on the side street here, do not have backplates, which I think were also added for visibility.
Title: Re: Strange Stop Light question.
Post by: roadman65 on September 27, 2022, 10:15:06 AM
Kansas uses them.  In Wichita most every intersection has one mounted to the mast arm poles.   I find them handy when you are behind semis.

In Illinois and California, they're usually mounted on its own pole on the near corner for that purpose.  Just like those two states are one's to mount far left corner left turn signals and supplemental permissive towers to have a back up turn signal where the other states have only one per MUTCD.  NJ (where I grew up) has those far left turn signal heads too, or if not always two mounted on overhead mast arms hence US 206 at CR 514 in Hillsborough.

Nonetheless, might be new for Kentucky, but age old in other states including its neighbor to the north (or north from Western KY).
Title: Re: Strange Stop Light question.
Post by: kphoger on September 27, 2022, 10:40:03 AM
In Wichita most every intersection has one mounted to the mast arm poles.

News to me.

Here's the one closest to my house.  No post-mounted signals.  https://goo.gl/maps/XBnBaoTqUnTCb7yL6

Here's just south of downtown at Kellogg.  Some have them, some don't.  https://goo.gl/maps/GBNkBwQdNG8EoVUr6

Not far away, there's this.  No post-mounted signals for the through street.  https://goo.gl/maps/uWcekiFy7hdqNC4v5

And here's downtown.  Some directions have them, some don't.  https://goo.gl/maps/ZDoGyaND4cdFXE2h7

Woodlawn @ K-96?  Nope.  https://goo.gl/maps/MDCFB1AYh8j9AEfb6

Broadway @ 29th?  Nope.  https://goo.gl/maps/heoTAwjFjXcHLEqK6

Lincoln @ Rock.  None for the through street.  https://goo.gl/maps/qAW5XJR8BTqubmcw6

Granted, it does appear that newer installations tend to have post-mounted supplemental signals.  But even something as new as northbound Rock Road at Kellogg doesn't have one (https://goo.gl/maps/tLcFrpT9qxUSG7Tq9)six signal heads but all overhead.
Title: Re: Strange Stop Light question.
Post by: jeffandnicole on September 27, 2022, 10:52:23 AM
At the intersection, the previous setup was 3 poles holding up the traffic lights.  Now it's 4 poles, creating a 'box'. This extra light is on Danville/US 68 WB.  But also on Danville/US 68 EB, a FYA was added for turning left onto Corporate Drive.  So, if I were to take a guess, due to that FYA the extra light was added to assist with motorists turning right having a light in their field of view, along with making it easier for pedestrians/bicyclists to see.