Two- vs three-section ramp meters

[Pink Jazz]

I know that ramp meters come in both two-section (R-G) and three-section (R-Y-G) variants.  I wonder, if your area has them, what type are used?  Also, what are the pros and cons to each?

Here in the Phoenix area, they are two-section models.

[Ian]

PennDOT has two-section ramp meters installed at the end of the on ramps to I-476 south of Plymouth Meeting.

[myosh_tino]

I know that ramp meters come in both two-section (R-G) and three-section (R-Y-G) variants.  I wonder, if your area has them, what type are used?  Also, what are the pros and cons to each?

Here in the Phoenix area, they are two-section models.

Really old ones in the S.F. Bay Area were a hybrid with a two-section at driver height and a three-section at the top of the pole (example: north Wolfe Rd to north I-280).  All new installations use 3-section lights (example: north Wolfe Rd to south I-280).

When metering is one car per green, the lights cycle red-green-red regardless of whether signals are two or three sections.  When metering is two cars per green in the Sacramento area, the metering lights cycle red-green-yellow-red presumably to give enough time for the second car to proceed before the red light is shown.  The only ramp that I know of in the S.F. Bay Area that is 2 per green are the CA-17 ramps to south CA-85 near Los Gatos but I do not know how that meter functions.

[lordsutch]

All the ones I've seen around Atlanta are 3-section; I've never seen yellow in use though.

[DaBigE]

In Wisconsin, if they're pole-mounted, both 2 and 3-section. The 3-section is up at the top and a 2-section is mounted 4-5' from ground level. If overhead-only, 3-section. The only time the yellow is used is when the ramp meters switch from rest in green to active metering. The yellow indication is not used as part of the active metering sequence (e.g., R>G>R>G...).

[riiga]

The only one I know of here uses standard traffic lights, so R-Y-G.

[PHLBOS]

I-205 in Portland, OR has some 3-section ramp meters.

[jakeroot]

Here are three images which illustrate the type of ramp meters used in my area:

The first image is the BC method, which entails side-mounted 12-12-12 signal-heads with sideways-pointed 8-8 signal-heads. But, they are rare in BC, and the only one I knew of, Mary Hill Bypass towards Highway 1, no longer exists following reconstruction of the Highway 1/Lougheed Highway interchange (the image I've linked is of this signal).

The second image is WSDOT method #1, which entails side-mounted 12-12-12 signal-heads with sideways-pointed 8-8-8 signal-heads. The example shown is of two single-lane ramp meters on a cloverleaf. Side-mounted signal-heads are used for one-lane meters and two-lane meters without HOV bypasses.

The third image is WSDOT method #2, which entails overhead-mounted 12-12-12 signal-heads, only used when there are two or more lanes (including those with metered shoulder lanes). 99% of the time, overhead signals are used when there are two lanes plus an HOV bypass, which doesn't allow for side-mounted signal-heads because the ramp is in the way. However, there are HOV bypass lanes which curve slightly around the second lane, allowing for two side-mounted signal-heads. But, this is uncommon.

Neither BC nor Washington have any two-per-green meters (AFAIK), so amber is not used during normal function. Can't speak for the brief moment when they are turned on, however...never witnessed this before.

   

[Kacie Jane]

Neither BC nor Washington have any two-per-green meters (AFAIK), so amber is not used during normal function. Can't speak for the brief moment when they are turned on, however...never witnessed this before.

I swear I've witnessed this exactly once... but I was in the mainline lanes and saw the yellow signal on the ramp out of the corner of my eye, so I could be imagining it.  But it was at a time when it would make sense for the ramp meter to just be coming on, and what I think I saw (again, out of the corner of my eye) would seem to match that: nothing lit, yellow, then red until the next car came to a stop at the signal.

[Pink Jazz]

As for style, overhead ramp meter signals are not common here in the Phoenix area; I have only seen them in a few places.  Most two lane ramps use pedestal-mounted meters on both sides, with the lower signals being angled towards the lane.  12 inch heads are used for the upper signals and 8 inch heads are used for the lower signals.

[SectorZ]

Not to jump completely off topic with this, is there any reason ramp meters are pretty much a non-starter in the Northeast? My travels have all been east of the Appalachians, and I've yet to actually encounter one.

[roadman65]

New York has one on the Grand Central Parkway and Arlington, VA has them leading onto I-66.

Of course, if Orlando had them on I-4 they would be a waste as nobody here would obey them unless you have cameras on every ramp.

[jakeroot]

Neither BC nor Washington have any two-per-green meters (AFAIK), so amber is not used during normal function. Can't speak for the brief moment when they are turned on, however...never witnessed this before.

I swear I've witnessed this exactly once... but I was in the mainline lanes and saw the yellow signal on the ramp out of the corner of my eye, so I could be imagining it.  But it was at a time when it would make sense for the ramp meter to just be coming on, and what I think I saw (again, out of the corner of my eye) would seem to match that: nothing lit, yellow, then red until the next car came to a stop at the signal.

I don't think your crazy. I mean, they shouldn't just suddenly become red, unless they want people rear-ending each other.

One day, I'm going to camp out and just wait. Or setup a camera. One or the other.

[DaBigE]

Neither BC nor Washington have any two-per-green meters (AFAIK), so amber is not used during normal function. Can't speak for the brief moment when they are turned on, however...never witnessed this before.

I swear I've witnessed this exactly once... but I was in the mainline lanes and saw the yellow signal on the ramp out of the corner of my eye, so I could be imagining it.  But it was at a time when it would make sense for the ramp meter to just be coming on, and what I think I saw (again, out of the corner of my eye) would seem to match that: nothing lit, yellow, then red until the next car came to a stop at the signal.

I don't think your crazy. I mean, they shouldn't just suddenly become red, unless they want people rear-ending each other.

One day, I'm going to camp out and just wait. Or setup a camera. One or the other.

FWIW, I have never seen the yellow indication illuminated in Wisconsin either...rather, IIRC, its operation was something I was told about by someone here on AARoads. When I toured the WisDOT Statewide Traffic Operations Center several years back I asked several employees there what/when the yellow indication was for on the ramp meters (at the time I figured it was a logical place to ask since they operate/oversee the metering operations). Not one of them had the foggiest clue what I was even talking about.

[roadfro]

Nevada uses two-section signal heads for all its ramp meters. Preferred mounting is overhead on a mast arm with one signal per lane. In limited applications where the meters are post mounted, then two signals are used (one high, one low and angled inward to the stop line).


I find it interesting that NDOT only uses one signal per lane with the overheads. Since the ramp meters typically operate in a staggered release mode (lanes alternate getting the greens), it means that there is no redundant signal head in case of signal head failure.

[Ace10]

I believe every ramp meter in Oregon has three heads. Side pole-mounted signals (with auxiliary 2-headed signals at driver height) are used when there are 1 or 2 lanes, and overhead mounted signals must be used for 3 lanes or more. I've never seen the yellow indication shown, but I believe it's for when the ramp signals are activated.

Ramp meter signals in Minnesota (at least in the Minneapolis area) are three-headed, and I noticed the yellow lights flash when the ramps are not being metered.

[myosh_tino]

Ramp meter signals in Minnesota (at least in the Minneapolis area) are three-headed, and I noticed the yellow lights flash when the ramps are not being metered.

That's interesting.  In the S.F. Bay Area, metering lights are set to green if the ramp is not being metered.

[JMAN_WiS&S]

In the twin cities area, I've never seen any of the ramp meters in use, but they are pole mounted on each side of the ramp, I'm pretty sure they are 8 inch signals because they look small, but I'm not 100% sure. The signals up top have backplates/fitted borders, and the driver signals don't. Each pole has a signal facing up the ramp and a signal at driver height facing the drivers window. The signals are RYG and flash yellow when not metering.

[Big John]

Ramp meter signals in Minnesota (at least in the Minneapolis area) are three-headed, and I noticed the yellow lights flash when the ramps are not being metered.

That's interesting.  In the S.F. Bay Area, metering lights are set to green if the ramp is not being metered.

In Wisconsin, they are also set to green when not being metered.  By Atlanta, they go dark when metering is off.

Also in Minnesota, it goes with a GYR progression with a very short yellow phase.

[myosh_tino]

Ramp meter signals in Minnesota (at least in the Minneapolis area) are three-headed, and I noticed the yellow lights flash when the ramps are not being metered.

That's interesting.  In the S.F. Bay Area, metering lights are set to green if the ramp is not being metered.

In Wisconsin, they are also set to green when not being metered.  By Atlanta, they go dark when metering is off.

Also in Minnesota, it goes with a GYR progression with a very short yellow phase.

Perhaps I should clarify...

Metering lights are set to green when ramps that are supposed to be metered are not.  This usually happens on holidays that fall during the week. All other times, they are turned off.

[cl94]

New York has two-section meters on the LIE and Northern State. Warning signs feature a graphic of a 2-section signal.

Columbus, Ohio has them at several places inside I-270, also two-section.

[TravelingBethelite]

As far as I know, Connecticut does not use either. Kurumi knows more about all of CT, and I, Fairfield County, so he could provide more insight on the topic. We would probably use R-Y-G if we did.

[PHLBOS]

PennDOT has two-section ramp meters installed at the end of the on ramps to I-476 south of Plymouth Meeting.

US 22 along the Lehigh Valley Expressway used to have similar 2-section signals; but were taken down sometime back (not sure when).  I know that 22 had them circa 2001-2002.

[theline]

Is anyone aware of a ramp meter in Indiana? I've never seen one. I was so unfamiliar with them that I ran one in California last fall. No harm done, fortunately. I was totally surprised to see a red light in that location.

[ekt8750]

PennDOT has two-section ramp meters installed at the end of the on ramps to I-476 south of Plymouth Meeting.

US 22 along the Lehigh Valley Expressway used to have similar 2-section signals; but were taken down sometime back (not sure when).  I know that 22 had them circa 2001-2002.

I think they were also on I-78 in the same Allentown-Bethlehem corridor. Don't remember if they too were taken down.