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Meter Light Standards

Started by KEK Inc., March 10, 2014, 05:51:46 AM

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Milepost61

Quote from: Scott5114 on March 11, 2014, 08:25:22 AM
Do they still use 12-8-8 heads?

Colorado switched from 12-8-8 to 12-12-12 with their most recent installations in the last year.


roadfro

Nevada uses the red/green setup with 12-12 signal heads. At the beginning of the ramp, there is the pedestrian-style "Meter On" display that indicates the ramp meter is active (flashing in Vegas, steady on in Reno's few installations)--a couple newer ramp meters in the Vegas area also include the MUTCD standard warning sign with single flashing beacon, to maintain that compliance.

The ramp meters are almost always mounted with only one overhead signal head per lane. Nevada also does staggered metering, such that the lanes alternate in the release of vehicles. This provides the interesting case of no backup/redundant display in case the signal head or section fails, which I think could be an issue. Interestingly, the seemingly permanent installations in Reno using two signal heads per lane (high and low side-mount signal heads) were eventually replaced with single overhead signal heads per lane.
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.

mrsman

Quote from: BrianP on June 15, 2021, 01:01:32 PM
I-270 RAMP METER TESTING BEGINS AS PART OF INNOVATIVE CONGESTION MANAGEMENT PROJECT
QuoteThe Maryland Department of Transportation State Highway Administration (MDOT SHA) is expected to activate and test a new ramp metering system on the ramp from northbound MD 118 to southbound I-270, in the Germantown area of Montgomery County on Wednesday, June 23. This will be the first location activated in the new ramp metering system that will eventually include 22 northbound and 23 southbound I-270 ramps.
QuoteThis single location will be activated as a flashing yellow signal on or about June 16, before becoming fully operational on June 23. MDOT SHA is testing the system at this single location for one week and will then deactivate it until the entire southbound I-270 ramp metering system is activated later this year. The northbound I-270 ramp metering system is expected to be activated in 2022.
QuoteThe signal will allow one car at a time to go from each lane, optimizing traffic flow onto I-270.
How do you allow just one car to go at a time?: 


Maryland is joining the states that provide for ramp metering as part of a larger I-270 project.

One thing that baffles me is that the video seems to suggest that once the project is functional, "when ramp metering is not in operation, the advanced beacon will be dark and the ramp meter signal will flash yellow."  Is this a common operation for ramp meters?  I am used to the flashing beacon being on to warn drivers to be watchful for the red and green stop and go lights.  I am also used to a flashing yellow indication on the ramp meter as a warning that the meter will be turning on soon.  But in times of light traffic, ramp meters are just typically dark [kind of like HAWK signals].  It would seem to me that if the flashing yellow is used as a warning that you may have to stop, it should not be on when the meter is not operating.

MCRoads

Quote from: Milepost61 on March 16, 2014, 12:01:56 AM
Quote from: Scott5114 on March 11, 2014, 08:25:22 AM
Do they still use 12-8-8 heads?

Colorado switched from 12-8-8 to 12-12-12 with their most recent installations in the last year.

Which is great for collecting signals, as CO has a lot of 12-8-8 heads that get discarded (if the scrapyard doesn't get them, they go on EBay a lot of the time)
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*/** indicates a terminus/termini being traveled
° Indicates a gap (I.E Breezwood, PA.)

more room plz

roadfro

Quote from: mrsman on June 15, 2021, 01:54:00 PM
Maryland is joining the states that provide for ramp metering as part of a larger I-270 project.

One thing that baffles me is that the video seems to suggest that once the project is functional, "when ramp metering is not in operation, the advanced beacon will be dark and the ramp meter signal will flash yellow."  Is this a common operation for ramp meters?  I am used to the flashing beacon being on to warn drivers to be watchful for the red and green stop and go lights.  I am also used to a flashing yellow indication on the ramp meter as a warning that the meter will be turning on soon.  But in times of light traffic, ramp meters are just typically dark [kind of like HAWK signals].  It would seem to me that if the flashing yellow is used as a warning that you may have to stop, it should not be on when the meter is not operating.

That's something I haven't seen before either.

Interestingly, the 2009 MUTCD's chapter on ramp metering doesn't disallow this. The only mention in the entire chapter about their operation is an option statement that allows the meter signal to be placed in dark mode (no indications displayed) when metering is not in use. So I guess the flashing yellow is allowable and could be analogous to flashing yellow used at older fire station or pedestrian crossing signals, in a "proceed with caution" context.

But I'm with you that I don't really like the idea of a flashing yellow in this context–probably because I've never encountered that before and everywhere I've seen a ramp meter uses the dark mode. But if practically every other state uses dark mode for non-functioning ramp meters, why can't MD get on board? I'd be curious if MD uses dark mode for any other type of signal (like HAWKs), and if not then maybe this is an effort to avoid displaying a dark signal...?
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.

roadfro

Quote from: roadfro on March 16, 2014, 04:22:09 PM
Nevada uses the red/green setup with 12-12 signal heads. At the beginning of the ramp, there is the pedestrian-style "Meter On" display that indicates the ramp meter is active (flashing in Vegas, steady on in Reno's few installations)--a couple newer ramp meters in the Vegas area also include the MUTCD standard warning sign with single flashing beacon, to maintain that compliance.

Updating myself from seven years ago. Nevada now installs the standard MUTCD warning sign ("ramp metered when flashing") and single yellow beacon to indicate when a meter is operating, and no longer regularly installs the pedestrian-style "meter on" display (although in some recent instances in Vegas, both were installed). I believe this is based on previous FHWA feedback or interpretation on those ped head-style devices. Those still in operation in the Vegas area no longer flash when operating and are steady on, while all instances in Reno have been replaced with standard sign and beacon.
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.

US 89

Utah uses full red/yellow/green, 12-12-12 signal heads for the vast majority of its ramp meters, though there are a small handful of older red/green 12-12s still standing. For multilane ramps, the meter lights are overhead with no side signals (typical example), though sometimes they'll have additional signals to the side (example). Single-lane ramps will have one pole to the side, with two signal heads - one facing traffic immediately next to the post and another facing approaching traffic (typical example here).

At most of them, the yellow light is only used when the meter is in the process of activating from dark mode. However, some of the meters allow 2 cars per green instead of the usual 1 - in these cases, the yellow light is used like a normal yellow light. Older R/G meters never allow more than 1 car per green, and they activate by turning on both the red and green lights for several seconds.

The "ramp metered when flashing" sign with alternating flashing beacons on either side (example) is the usual warning sign now. The old standard was a yellow "metering when flashing" along a variant of the MUTCD traffic signal warning sign (W3-3) with only the red and green, accompanied by a pair of alternating flashing beacons (example), although some ramps only had the signal-ahead sign and some just had the text-only sign. Not many of those are left.

I'm 90% sure I have seen one of the pedestrian-style "METER ON" signs somewhere in the SLC/Davis County area, but this was probably 10-15 years ago and I cannot figure out where the hell it was. It's almost certainly gone now given multiple reconstruction and resigning projects have occurred in this area since then.

RobbieL2415

I don't know what the setup was for CT's only extinct ramp meter, at the on-ramp from CT 17 to CT 9 north in Middletown.

There was at least a small R-G signal.

ErmineNotyours

In defense of ramp meters.


bcroadguy

BC only ever had one ramp meter which has been gone for almost 10 years and this is what it looked like.

The new Mountain Highway Interchange in North Vancouver, which is nearing completion, is supposed to get a ramp meter so it will be interesting to see if they keep the same standard.


Amtrakprod

I think it makes the most sense to have the signal flash yellow, (what MN does). In WI the signals stay green, Which seems dangerous to me, and in other states, the dark indication seems confusing.


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andrepoiy

Ontario has 8-8-8 signals.


jakeroot

Quote from: andrepoiy on June 17, 2021, 07:00:47 PM
Ontario has 8-8-8 signals.



Could you share a Google Maps link? From here, they look a lot like 12-12-12.

andrepoiy

Quote from: jakeroot on June 17, 2021, 07:53:44 PM
Quote from: andrepoiy on June 17, 2021, 07:00:47 PM
Ontario has 8-8-8 signals.



Could you share a Google Maps link? From here, they look a lot like 12-12-12.

You're right, they changed them to 12-12-12. I now see the difference. (If you click to an older Streetview picture it was indeed 8-8-8)

https://goo.gl/maps/Xmovbsk1gBgScvbH8

jakeroot

One interesting thing about those Ontario meter lights is the placement. Usually limit-line meter signals (the standard in most places for single-lane meters) have an additional signal oriented towards the stop bar. These two signals seem like they would be harder to see when stopped at the limit line.

ran4sh

Georgia, for a 2-lane onramp, normally installs a mast arm and mounts the ramp meters on there. There are 2 overhead ramp meters for each lane because GA uses staggered release in those situations. Georgia did request an MUTCD interpretation from FHWA regarding the number and positioning of ramp meters for multi-lane onramps with staggered release; they have generally followed that interpretation. https://mutcd.fhwa.dot.gov/resources/interpretations/4_294.htm

https://goo.gl/maps/bgAEm5GX9BNu9i1E6
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roadfro

Quote from: ran4sh on June 18, 2021, 08:28:48 PM
Georgia, for a 2-lane onramp, normally installs a mast arm and mounts the ramp meters on there. There are 2 overhead ramp meters for each lane because GA uses staggered release in those situations. Georgia did request an MUTCD interpretation from FHWA regarding the number and positioning of ramp meters for multi-lane onramps with staggered release; they have generally followed that interpretation. https://mutcd.fhwa.dot.gov/resources/interpretations/4_294.htm

https://goo.gl/maps/bgAEm5GX9BNu9i1E6
Interesting...  The official interpretation from MUTCD dates from 2005, and says a multi-lane ramp using staggered release should have two signal faces per lane.

However, the wording of the interpretation was not made a standard in the 2009 MUTCD. It requires only one overhead signal per lane (mounted over the center of the lane), although a guidance statement recommends considering a second, side-mounted signal head for each lane.

This makes Nevada's implementation of ramp meters more interesting. Nevada is a state that follows MUTCD standards closely and also usually implements most guidance statements, and also has side-mount redundancy at the vast majority of traditional traffic signals. Most of Nevada's ramp meters date from the era of 2009 MUTCD, and all of them date after the Interpretation. However, we use staggered release on all multi-lane ramp meters, but there are virtually no ramps with more than one signal per lane.
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.

Jet380

Quote from: ran4sh on June 18, 2021, 08:28:48 PM
Georgia, for a 2-lane onramp, normally installs a mast arm and mounts the ramp meters on there. There are 2 overhead ramp meters for each lane because GA uses staggered release in those situations. Georgia did request an MUTCD interpretation from FHWA regarding the number and positioning of ramp meters for multi-lane onramps with staggered release; they have generally followed that interpretation. https://mutcd.fhwa.dot.gov/resources/interpretations/4_294.htm

https://goo.gl/maps/bgAEm5GX9BNu9i1E6

Funnily enough, at the other onramp at that interchange, they seem to have changed it from two signals per lane to just one. Have a look the historical images here: https://goo.gl/maps/yjf3jrVzxBNgJNvGA

For an overseas perspective, the newly-installed meters here in Perth all use 8-8-8 signals.

https://goo.gl/maps/MhXAubzraCK9w5fM8

Interestingly, they have done their best to imitate US-style signals with some features not found at other traffic lights in Perth. For example, the ramp meters generally have far-side gantries with multiple signal faces, whereas at normal intersections, overhead signals are rare and are generally near-side with only one signal face.

Our ramp meters are also operated a bit differently. During metering, the signals go through the full G-Y-R but with a comically short yellow. Staggered starts are not used at all, so it is left to motorists to figure out who should go in front. Does anywhere in the US operate this way?

zachary_amaryllis

Quote from: Jet380 on June 19, 2021, 02:40:33 AM

Our ramp meters are also operated a bit differently. During metering, the signals go through the full G-Y-R but with a comically short yellow. Staggered starts are not used at all, so it is left to motorists to figure out who should go in front. Does anywhere in the US operate this way?

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jakeroot

Quote from: roadfro on June 19, 2021, 01:49:35 AM
Nevada is a state that follows MUTCD standards closely and also usually implements most guidance statements, and also has side-mount redundancy at the vast majority of traditional traffic signals. Most of Nevada's ramp meters date from the era of 2009 MUTCD, and all of them date after the Interpretation. However, we use staggered release on all multi-lane ramp meters, but there are virtually no ramps with more than one signal per lane.

Certain districts of California also use the overhead-only, one-per-lane strategy similar to Nevada and Washington State. Example in San Jose like that. Very odd, since California is normally quite mental about two signals per movement. Down in Southern California, however, it seems to be the norm to use post-mounted signals whenever physically possible (so you get odd things like this and this, but normally everything is like this (similar to WSDOT's alternate style).




Quote from: ran4sh on June 18, 2021, 08:28:48 PM
Georgia, for a 2-lane onramp, normally installs a mast arm and mounts the ramp meters on there. There are 2 overhead ramp meters for each lane because GA uses staggered release in those situations. Georgia did request an MUTCD interpretation from FHWA regarding the number and positioning of ramp meters for multi-lane onramps with staggered release; they have generally followed that interpretation. https://mutcd.fhwa.dot.gov/resources/interpretations/4_294.htm

https://goo.gl/maps/bgAEm5GX9BNu9i1E6

Has Georgia not heard of a post or pedestal? The best time to use them is at ramp meters, and they still refuse to use them (that MUTCD question indicates some concern about mixing overhead and post-mounted signals ... based on what evidence?). In fact, I cannot recall ever seeing a post-mounted signal in George. Do they even exist anywhere? Apart from DDIs or other offset intersections.

Big John


ran4sh

I don't usually defend GDOT but I'll do it here. Why would it be appropriate to use a post mounted signal for a 2-lane ramp, unless the post is all the way off the shoulder (which would reduce its conspicuousness). The overhead mast arm, with the pole being far enough off the shoulder and protected with guardrail, seems to be the ideal ramp meter setup.

(I'm actually not in favor of ramp meters at all, they're a symptom of failing to provide enough transportation capacity. [they only exist because they're cheaper than actually reducing congestion and/or increasing capacity])
Control cities CAN be off the route! Control cities make NO sense if signs end before the city is reached!

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froggie

Quote from: ran4sh(I'm actually not in favor of ramp meters at all, they're a symptom of failing to provide enough transportation capacity. [they only exist because they're cheaper than actually reducing congestion and/or increasing capacity])

That is not the only reason they exist.  They provide significant benefits in terms of both crash reduction and flow stability, at a rate far greater than your "increasing capacity" would.

Scott5114

Basically, ramp meters are intended to use the same amount of capacity more efficiently, increasing the number of vehicles that can pass through the same number of lanes. Sort of like replacing an incandescent bulb with a brighter LED light; you're getting more of what you want in the same space and cost footprint as the original.
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jakeroot

Quote from: ran4sh on June 19, 2021, 04:58:31 PM
I don't usually defend GDOT but I'll do it here. Why would it be appropriate to use a post mounted signal for a 2-lane ramp, unless the post is all the way off the shoulder (which would reduce its conspicuousness). The overhead mast arm, with the pole being far enough off the shoulder and protected with guardrail, seems to be the ideal ramp meter setup.

My primary issue with overhead only ramp meter signals is that they are inconspicuous when the sun is behind them. This is an issue with all signals, but is more apparent with ramp meters as they are typically active only during sun-up and sun-down times. As ramps are also quite often angled up or down, this can sometimes mean the roadway geometry exacerbates the issue even further (positive-angle on-ramps are pointing up towards a rising or setting sun).

Using two signals per lane, but all overhead (the first GA example), also means you are placing the signals too close together under MUTCD rules (less than eight feet); this then requires additional signage to indicate which signals belong to which lane.

Good setups, by comparison, are in places like California and Washington: signals are in the shoulder, closer to eye level and thus you are not being blinded; there is redundancy; it is very clear which signal is for which lane simply by the placement of the signals (left or right side of the roadway). Three-lane meters obviously need overhead signals, but you can still supplement the outside lanes with post-mounted signals. Or just bulb-out one side!

For the record, I am not aware of any outstanding issues regarding signal mast/signal pole conspicuity in terms of them being hit. I assume this concern is rooted in the idea that pole-mounted signals are more prevalent to being knocked down. This isn't false, per se, but I don't believe it's an issue with ramp meter signals. Keep in mind that pole-mounted ramp meter signals are by far the most common setup in the US, and I doubt this would be the case if they were regularly knocked down.



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