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National Boards => General Highway Talk => Traffic Control => Topic started by: tradephoric on July 01, 2014, 01:30:38 PM

Title: Too many traffic signals?
Post by: tradephoric on July 01, 2014, 01:30:38 PM
The picture below highlights all the state run signals in Orlando.  Many of these arterials, some well outside of the city core, have signals spaced less than 1/4 mile apart.  I'm not picking on Orlando as it seems every major city have an abundance of traffic signals controlling traffic (quite often inefficiently).

(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi478.photobucket.com%2Falbums%2Frr144%2Ftradephoric%2FTransportation%2520Pictures%2FRandom%2Funtitled22_zps91405fc3.png&hash=e05be370be7fe25f54042bcce9974e7d7793fa9a) (http://s478.photobucket.com/user/tradephoric/media/Transportation%20Pictures/Random/untitled22_zps91405fc3.png.html)

Any ideas on how to reduce the density of traffic signals that drivers encounter in major metros?

Title: Re: Too many traffic signals?
Post by: agentsteel53 on July 01, 2014, 01:59:39 PM
Orlando is terrible; not just for the signals, but for their bad timing.  I once drove 441 all the way through town.  I counted 126 signals.  6 were green.
Title: Re: Too many traffic signals?
Post by: ET21 on July 01, 2014, 02:12:43 PM
Try Chicago  :-D

Signals and stop signs every couple hundred feet on some streets
Title: Re: Too many traffic signals?
Post by: jakeroot on July 02, 2014, 12:16:41 AM
Reducing signals? Well, RIRO with U-turns seems the most logical, but there isn't always space for that.

- For the expressways, no left turns. This isn't always possible, but a straight followed by three rights will force traffic to spill into nearby areas but the now two-phase signals should filter traffic faster.
- On the side streets, remove every other signal so as to make the intersection a priority road meeting a non-priority road (so two stop signs). I think people will eventually learn to use the road with signals.
- Less turn lights...make some of the signals two-phase. I've always thought that dedicated turn lights were over-used. Some intersections will require them, but certainly not all of them.

Plenty of errors with my theories, but I'm just spitballing.
Title: Re: Too many traffic signals?
Post by: hotdogPi on July 02, 2014, 07:25:06 AM
If there are evenly spaced traffic lights in any area, make them timed for both directions to get green lights. (It can only be done in one direction if they're not evenly spaced.)
Title: Re: Too many traffic signals?
Post by: tradephoric on July 02, 2014, 09:44:43 AM
Quote from: 1 on July 02, 2014, 07:25:06 AM
If there are evenly spaced traffic lights in any area, make them timed for both directions to get green lights. (It can only be done in one direction if they're not evenly spaced.)

The idea of getting a green wave in both directions of travel was touched on in another thread.  You need to run a "resonant cycle" which turns out to be 2X the travel time (the problem is, a resonant cycle can be very difficult to achieve because the evenly spaced signals are often spaced too close together).  As an exaggerated point, Park Avenue in Manhattan has evenly spaced traffic signals, yet it is impossible to coordinate the traffic lights for both directions. 

https://www.aaroads.com/forum/index.php?topic=11138.msg265706#msg265706
Title: Re: Too many traffic signals?
Post by: cpzilliacus on July 02, 2014, 09:56:00 AM
Quote from: agentsteel53 on July 01, 2014, 01:59:39 PM
Orlando is terrible; not just for the signals, but for their bad timing.  I once drove 441 all the way through town.  I counted 126 signals.  6 were green.

Ever been to the District of Columbia? And more-importantly, ever driven on its arterial streets?
Title: Re: Too many traffic signals?
Post by: 1995hoo on July 02, 2014, 10:06:02 AM
The thing I find weird is when you can catch a green wave only if you stay a couple of miles an hour above the posted speed limit. The twinned one-way segments of US-1 through Alexandria, Virginia, for example, are posted with a 25-mph speed limit, but if you go through there at about 32 mph you can manage to hit all the green lights in succession and get all the way to the other end without having to stop. If you go 25 mph, you will hit at least one red light.
Title: Re: Too many traffic signals?
Post by: freebrickproductions on July 02, 2014, 11:03:31 AM
Reminds me of University Drive here in Huntsville along with several other streets:
https://maps.google.com/maps/ms?msid=214814604170748480658.0004e96a62bd72fe03e52&msa=0
Title: Re: Too many traffic signals?
Post by: tradephoric on July 02, 2014, 11:29:38 AM
Quote from: freebrickproductions on July 02, 2014, 11:03:31 AM
Reminds me of University Drive here in Huntsville along with several other streets:
https://maps.google.com/maps/ms?msid=214814604170748480658.0004e96a62bd72fe03e52&msa=0

One nice thing about University Drive is it has a Parclo B4 at the 255 interchange.  I've been a strong proponent of Parclo B4 interchanges since they improve coordination (on/off ramp traffic signals only stop one direction of travel).  In theory, drivers going straight on University should never hit a red light at the interchange traffic signals.
Title: Re: Too many traffic signals?
Post by: froggie on July 02, 2014, 02:43:20 PM
QuoteEver been to the District of Columbia? And more-importantly, ever driven on its arterial streets?

I have.  Some arterials are better than others.  But even the "worse" ones aren't as bad as that Orlando example.