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Traffic signal

Started by Tom89t, January 14, 2012, 01:01:45 AM

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SkyPesos

I found a diagram for transit signals:

Kind of wondering, what is even the point of the "yellow" triangle phase of the 3 section signal. Unlike cars, most light rail signals I've seen are timed to turn to the vertical line when a train arrives, so most trains don't even see the triangle phase of the signal, or it turning to the horizontal line, which would make the 2 section signal adequate.


US 89

The TRAX light rail in Salt Lake uses that type of signal, though there is never a "prepare to stop" triangle. Instead, the "go" vertical bar will flash a few times to indicate the coming change to the "stop" horizontal bar. As far as light timing... yeah, the lights do know when a train is coming and absolutely factor that into cycle length and such, but the train doesn't completely preempt the lights. Trains have to stop at lights all the time out there.

There are also a few of these on that system. I imagine they are some kind of switch signal, but I have no idea even what colors/symbols are included, much less how to read them.

Rothman

Quote from: SkyPesos on November 30, 2021, 12:02:21 AM
I found a diagram for transit signals:

Kind of wondering, what is even the point of the "yellow" triangle phase of the 3 section signal. Unlike cars, most light rail signals I've seen are timed to turn to the vertical line when a train arrives, so most trains don't even see the triangle phase of the signal, or it turning to the horizontal line, which would make the 2 section signal adequate.
Bus priority signals in NY look like this.
Please note: All comments here represent my own personal opinion and do not reflect the official position(s) of NYSDOT.

Dirt Roads

Quote from: SkyPesos on November 30, 2021, 12:02:21 AM
I found a diagram for transit signals:

Kind of wondering, what is even the point of the "yellow" triangle phase of the 3 section signal. Unlike cars, most light rail signals I've seen are timed to turn to the vertical line when a train arrives, so most trains don't even see the triangle phase of the signal, or it turning to the horizontal line, which would make the 2 section signal adequate.

The triangle phase is needed on systems where there is not preemption for the LRT/streetcar system.  That triangle phase can also be deleted with certain types of traffic signal phasing set when the LRT/streetcar station stop is near the intersection.

Quote from: US 89 on November 30, 2021, 01:36:03 AM
The TRAX light rail in Salt Lake uses that type of signal, though there is never a "prepare to stop" triangle. Instead, the "go" vertical bar will flash a few times to indicate the coming change to the "stop" horizontal bar. As far as light timing... yeah, the lights do know when a train is coming and absolutely factor that into cycle length and such, but the train doesn't completely preempt the lights. Trains have to stop at lights all the time out there.

There are also a few of these on that system. I imagine they are some kind of switch signal, but I have no idea even what colors/symbols are included, much less how to read them.

I'm not familiar with the specifics of TRAX signalling, but the diagram above includes all of the aspects needed for switch.  But it looks like the fresnel lenses are indeed red/yellow and perhaps green, rather than the standard white.  The main reason to avoid red/yellow/green in LRT/streetcar signalling is, of course, to avoid confusing roadway traffic.  When the switch is located away from the street running portion of the system, the LRT signals can indeed be other colors.  However, this one is in the middle of the street where it could be confused with a mid-block crosswalk.

roadman65

RDIC uses them in Disney World for the bus lanes.  I saw the flashing triangle that is equal to the amber phase of standard signals on Buena Vista Drive.
Every day is a winding road, you just got to get used to it.

Sheryl Crowe

US 89

#4380
Quote from: Dirt Roads on November 30, 2021, 12:27:53 PM

Quote from: US 89 on November 30, 2021, 01:36:03 AM
The TRAX light rail in Salt Lake uses that type of signal, though there is never a "prepare to stop" triangle. Instead, the "go" vertical bar will flash a few times to indicate the coming change to the "stop" horizontal bar. As far as light timing... yeah, the lights do know when a train is coming and absolutely factor that into cycle length and such, but the train doesn't completely preempt the lights. Trains have to stop at lights all the time out there.

There are also a few of these on that system. I imagine they are some kind of switch signal, but I have no idea even what colors/symbols are included, much less how to read them.

I'm not familiar with the specifics of TRAX signalling, but the diagram above includes all of the aspects needed for switch.  But it looks like the fresnel lenses are indeed red/yellow and perhaps green, rather than the standard white.  The main reason to avoid red/yellow/green in LRT/streetcar signalling is, of course, to avoid confusing roadway traffic.  When the switch is located away from the street running portion of the system, the LRT signals can indeed be other colors.  However, this one is in the middle of the street where it could be confused with a mid-block crosswalk.

The thing though is that every example I can find of those round signals is before a switch, either a crossover from one track to another or a junction with another light rail line. The signals associated with the traffic lights are the square white ones that match up with the table posted upthread.

Here's another example on another approach to the same junction. The two square white signals control the two possible train movements at the switch ahead, straight on Main or left on 400 South (it helps that the left one is labeled "UNIV" and the right one "SANDY" - the original destinations of those lines). Although they aren't stacked or aligned the same way as the ones in the table SkyPesos posted, the indications match up.

The fact that these 3-section (or 2-section in some cases) round colored signals are provided in addition to the standard square white ones suggests to me that they mean something beyond just stop or go. These ones are unhelpfully labeled "M8" and "M10".

EDIT: I found an example of one of those round signals showing something other than a red horizontal bar in the bottom. My guess is the round signals have to do with the track switch itself, as opposed to the square ones which have to do with traffic lights and car/pedestrian movements that may be going on at the same time. I'd be curious to know what's in the middle, though.

Dirt Roads

Quote from: US 89 on November 30, 2021, 11:23:48 PM
The thing though is that every example I can find of those round signals is before a switch, either a crossover from one track to another or a junction with another light rail line. The signals associated with the traffic lights are the square white ones that match up with the table posted upthread.

Here's another example on another approach to the same junction. The two square white signals control the two possible train movements at the switch ahead, straight on Main or left on 400 South (it helps that the left one is labeled "UNIV" and the right one "SANDY" - the original destinations of those lines). Although they aren't stacked or aligned the same way as the ones in the table SkyPesos posted, the indications match up.

The fact that these 3-section (or 2-section in some cases) round colored signals are provided in addition to the standard square white ones suggests to me that they mean something beyond just stop or go. These ones are unhelpfully labeled "M8" and "M10".

EDIT: I found an example of one of those round signals showing something other than a red horizontal bar in the bottom. My guess is the round signals have to do with the track switch itself, as opposed to the square ones which have to do with traffic lights and car/pedestrian movements that may be going on at the same time. I'd be curious to know what's in the middle, though.

Just in case I wasn't clear, you are correct that LRT signals (that are not for street running) are associated with the railway switches.  The middle aspect on that signal is probably an "amber" fresnel lens with a diagonal slot (angled in the direction of the "reverse" move through the switch, given that the "tangent" (straight) move also has an "amber" lens.  Those appear to be just like the ones we use on the railroad, which are a bit different than the "yellow" lenses used for traffic signals.  But I have seen where some properties have improvised using red/yellow/green layout, it's just that those signals cannot be used anywhere near a traffic intersection (because they don't meet MUTCD requirements).

For the record, I would not have approved the use of these signals at this location because they don't meet MUTCD requirements (which were certainly in the contract requirements).

jay8g

Seattle uses those LRT-style signal heads extensively for bus signals. However, the original streetcar line includes this weird signal, with a hollow yellow triangle for the "go" indication.

And speaking of weird rail signals, I've always found the ones at the Westlake monorail station to be interesting. I'm not entirely sure what the point of those signals is, seeing as if two trains were at that station at the same time, there would be much larger problems!

Dirt Roads

Quote from: jay8g on December 05, 2021, 03:04:01 AM
Seattle uses those LRT-style signal heads extensively for bus signals. However, the original streetcar line includes this weird signal, with a hollow yellow triangle for the "go" indication.

And that one's not MUTCD-compliant, either.  At least it seems like the LRT/streetcar folks are avoiding the use of green lenses.  But they are supposed to be white aspects when street-running.


Quote from: jay8g on December 05, 2021, 03:04:01 AM
And speaking of weird rail signals, I've always found the ones at the Westlake monorail station to be interesting. I'm not entirely sure what the point of those signals is, seeing as if two trains were at that station at the same time, there would be much larger problems!

Never seen that type before.  On the Seattle Center Monorail system, there is only one train on each guideway but there is this one area where the guideways get too close to each other and the trains need to stay separated.  The placement of these signals is odd, since the operators (drivers) might not be able to see the signals under the monobeam in certain situations.  And I hate to say it, but the placement of green and yellow signal aspects some 20 feet over the street is still not compliant with MUTCD.

jakeroot

Quote from: Dirt Roads on December 05, 2021, 05:40:32 PM
Quote from: jay8g on December 05, 2021, 03:04:01 AM
Seattle uses those LRT-style signal heads extensively for bus signals. However, the original streetcar line includes this weird signal, with a hollow yellow triangle for the "go" indication.

And that one's not MUTCD-compliant, either.  At least it seems like the LRT/streetcar folks are avoiding the use of green lenses.  But they are supposed to be white aspects when street-running.

That's interesting. The Tacoma Link streetcar uses amber stop symbols, although the 'go' symbol is white: https://goo.gl/maps/TZEPU8WFR9xGu7UQ7

The new extension uses all-white displays; this earlier stretch opened in 2003. Did the rule change?

Dirt Roads

Quote from: jay8g on December 05, 2021, 03:04:01 AM
Seattle uses those LRT-style signal heads extensively for bus signals. However, the original streetcar line includes this weird signal, with a hollow yellow triangle for the "go" indication.

Quote from: Dirt Roads on December 05, 2021, 05:40:32 PM
And that one's not MUTCD-compliant, either.  At least it seems like the LRT/streetcar folks are avoiding the use of green lenses.  But they are supposed to be white aspects when street-running.

Quote from: jakeroot on December 05, 2021, 11:13:36 PM
That's interesting. The Tacoma Link streetcar uses amber stop symbols, although the 'go' symbol is white: https://goo.gl/maps/TZEPU8WFR9xGu7UQ7

The new extension uses all-white displays; this earlier stretch opened in 2003. Did the rule change?

The oldest MUTCD that I have handy is from 2000, and that has the same signal chart requiring white aspects.  My first street-running LRT project was back in 1992, but I'm not sure if the white aspect rule was in the MUTCD back in those days.  I dig around some more at a later date.

For the record, I'll have to admit that I'm one of the few rail transit guys that is a stickler for all of MUTCD rules on traffic signals (that's because I morphed over from signalling into safety certification).  Many of the engineers in the LRT world either came from the old streetcar world or somewhere else (think subways and railroading, but I know some that came from other areas as well).  Old habits are hard to break.  It is not unsafe to use yellow aspects for streetrunning, because a confused driver or LRT operator should interpret the signal as "prepare to stop at this signal".  But in railroading and subways, the simple yellow aspect means "prepare to stop at next signal".  Therefore, yellow aspects are not to be used in street-running applications.

Dirt Roads

^ Indeed, there is no reference to LRT/streetcar signals in the 1988 version of the MUTCD.  The "white aspect rule" would have only been required by contract specification for projects started prior to the inclusion of the 2000 version of the MUTCD.  And some later projects might not have remembered to include MUTCD for street-running LRT signalling rules.

jakeroot

Quote from: Dirt Roads on December 06, 2021, 10:50:44 AM
^ Indeed, there is no reference to LRT/streetcar signals in the 1988 version of the MUTCD.  The "white aspect rule" would have only been required by contract specification for projects started prior to the inclusion of the 2000 version of the MUTCD.  And some later projects might not have remembered to include MUTCD for street-running LRT signalling rules.

Planning for the Tacoma Link streetcar (again, opened 2003) would have certainly begun in the late 1990s, possibly before that white aspect rule came into place. I don't suppose the 2000 MUTCD was adopted soon enough for them to have enough time to change to all-white aspects. Or, the signals were designed prior to the 2000 MUTCD adoption and thus were not required to have been all-white.

More confusing, the South Lake Union Trolley (SLUT) was opened in 2007, well after that MUTCD was adopted, but also uses amber aspects; I suppose it could have had its signals designed prior to the 2000 MUTCD adoption, but it seems far less likely. The Broadway streetcar in Seattle uses all-white displays, however.

jakeroot

Here's an inquiry for roadfro, if he sees it:

In Reno, NV, I noticed the double right turn from Neil Rd to southbound 395/580 freeway is a "yield". Not too weird, but after checking out historic street view, I noticed that there were plans to signalize this movement. Note in this image from July 2011, there is an inactive vehicular signal on the far side of the intersection, and two pedestrian signals on either side of the crosswalk. One month later, the pedestrian signals remain but the vehicular signals have been removed. At some point thereafter, the pedestrian signals in the island were modified to only have two brackets and the extra pedestrian signal removed, and the far side of the crosswalk had its pedestrian signal removed although there is physical evidence of its existence. All the while, the stop line (instead of sharks teeth) remains across the slip lane, as though there were a signal or stop condition for this movement.

So, as to the point: any idea why they decided against signalizing this movement? I can usually understand not wanting a signalized double right turn via a slip lane opposite a permissive left turn, but the left turn onto the on-ramp is protected-only. In addition, to the best of my knowledge, Nevada doesn't use double right turn yields often, if much at all (perhaps very rare?), so this seems like an odd setup.

Some pictures for reference:

The double right turn as it appears today:


Neil Rd at 395/580 Fwy -- March 2021 by Jacob Root, on Flickr

As it appeared in the summer of 2011:


Neil Rd at 395/580 Fwy -- July 2011 by Jacob Root, on Flickr

STLmapboy

Quote from: jakeroot on December 08, 2021, 12:23:42 PM
Here's an inquiry for roadfro, if he sees it:

In Reno, NV, I noticed the double right turn from Neil Rd to southbound 395/580 freeway is a "yield". Not too weird, but after checking out historic street view, I noticed that there were plans to signalize this movement. Note in this image from July 2011, there is an inactive vehicular signal on the far side of the intersection, and two pedestrian signals on either side of the crosswalk. One month later, the pedestrian signals remain but the vehicular signals have been removed. At some point thereafter, the pedestrian signals in the island were modified to only have two brackets and the extra pedestrian signal removed, and the far side of the crosswalk had its pedestrian signal removed although there is physical evidence of its existence. All the while, the stop line (instead of sharks teeth) remains across the slip lane, as though there were a signal or stop condition for this movement.

So, as to the point: any idea why they decided against signalizing this movement? I can usually understand not wanting a signalized double right turn via a slip lane opposite a permissive left turn, but the left turn onto the on-ramp is protected-only. In addition, to the best of my knowledge, Nevada doesn't use double right turn yields often, if much at all (perhaps very rare?), so this seems like an odd setup.

Some pictures for reference:

The double right turn as it appears today:


Neil Rd at 395/580 Fwy -- March 2021 by Jacob Root, on Flickr

As it appeared in the summer of 2011:


Neil Rd at 395/580 Fwy -- July 2011 by Jacob Root, on Flickr

Interesting. I looked at the 2007 GSV from 580 and it seems to indicate that the inactive right-turn signal which was removed in 2011 was there four years before.
Teenage STL area roadgeek.
Missouri>>>>>Illinois

roadfro

Quote from: STLmapboy on December 09, 2021, 12:00:25 AM
Quote from: jakeroot on December 08, 2021, 12:23:42 PM
Here's an inquiry for roadfro, if he sees it:

In Reno, NV, I noticed the double right turn from Neil Rd to southbound 395/580 freeway is a "yield". Not too weird, but after checking out historic street view, I noticed that there were plans to signalize this movement. Note in this image from July 2011, there is an inactive vehicular signal on the far side of the intersection, and two pedestrian signals on either side of the crosswalk. One month later, the pedestrian signals remain but the vehicular signals have been removed. At some point thereafter, the pedestrian signals in the island were modified to only have two brackets and the extra pedestrian signal removed, and the far side of the crosswalk had its pedestrian signal removed although there is physical evidence of its existence. All the while, the stop line (instead of sharks teeth) remains across the slip lane, as though there were a signal or stop condition for this movement.

So, as to the point: any idea why they decided against signalizing this movement? I can usually understand not wanting a signalized double right turn via a slip lane opposite a permissive left turn, but the left turn onto the on-ramp is protected-only. In addition, to the best of my knowledge, Nevada doesn't use double right turn yields often, if much at all (perhaps very rare?), so this seems like an odd setup.

Some pictures for reference:

The double right turn as it appears today:


Neil Rd at 395/580 Fwy -- March 2021 by Jacob Root, on Flickr

As it appeared in the summer of 2011:


Neil Rd at 395/580 Fwy -- July 2011 by Jacob Root, on Flickr

Interesting. I looked at the 2007 GSV from 580 and it seems to indicate that the inactive right-turn signal which was removed in 2011 was there four years before.

I'm not entirely certain... But I think I have an explanation given other contextual factors.

First some context. The area around the US 395/Neil Road interchange has long been one of the biggest and busiest commercial business districts of the Reno area. Meadowood Mall was constructed in the late 1970s as development in Reno was moving further south from downtown. Note that Virginia Street in the area is the original US 395 highway, and the freeway construction reached the half interchange at Virginia St (what's now exit 31) in 1981. A lot of the shopping centers in the area started getting developed after that, with much of it coming in the mid-late 1990s (especially all of it along Kietzke Lane, which itself was extended south from Virginia Street during the 80s. As this area built up as the main commercial shopping area of the region and a lot of new housing was being built further south, one lacking mobility element was that the half-interchange didn't allow for freeway entry to the south, so the nearest place for all of this shopping traffic to head back to the south meadows region was the interchange at Neil Road (formerly Del Monte Lane).

When I came to Reno for college in 2001, the intersection of Kietzke Lane and Neil Road was a 4-way stop. This all-way stop would often have long back-ups on Kietzke for those coming from retail areas to the north trying to access US 395 south. By Historic Aerials imagery, the intersection was converted to a roundabout somewhere between 2006 and 2010 (based on the StreetView STLmapboy found, the roundabout was likely completed in 2007). Part of the reason for the roundabout construction was to make the southbound left turn from Kietzke to eastbound Neil the predominant movement, and the dual right turn lane from Neil Road to US 395 south was constructed simultaneously with the roundabout. I can't recall for sure (I've always lived in northern Reno, so never had much occasion to use this movement), but I'm fairly certain that the dual right turn was fully signalized as a protected right turn when it was initially constructed.

Keep in mind during all this time, what is now Meadowood Mall Way did not exist beyond the Best Buy. In the 2000s, the Washoe County RTC had begun planning to punch Meadowood Mall Way through under US 395 to Kietzke Lane and create a new interchange. The eventual design is what we have today–Niel Road was converted from a full diamond to a split diamond with Meadowood Mall Way, providing new circulation in the area and a more direct means for some of the retail traffic to access US 395 southbound (as well as providing some relief to the existing half diamond at Virginia). Much of Washoe County's ARRA stimulus funding went in to making this project happen, which started (I believe) in late 2009 and completed sometime in 2012–panning left from the July 2011 street view jakeroot linked, you can see construction on the southbound off ramp and its conversion to frontage road in the distance. 

So with that context, my assumption is that the Meadowood Mall interchange and new southbound frontage road linking to Neil Road was expected to cause traffic patterns to shift considerably, resulting in less demand for this movement to US 395 south. Given the reduced demand for this movement, I would assume they thought it prudent to remove the signalization for this turn, but didn't think it would be a big deal to leave the striping unchanged. It does result in one of the few dual right turn lane situations in Nevada that I'm aware of that is not signalized.
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.

Caps81943


plain

#4392
Quote from: Caps81943 on December 14, 2021, 05:58:09 PM
https://www.google.com/maps/@21.3708172,-157.9315724,3a,22.2y,273.04h,91.99t/data=!3m6!1e1!3m4!1s2VbhlaYLw7SpjYG2EIXXLA!2e0!7i16384!8i8192

Very old arrow signal in Hawaii.

Nice find! Definitely don't see many of those old arrows now.

HI seems to have a lot of wild stuff going on. Here's an intersection I meant to post a while back but forgot. Two typical Hawaii 3M PV left turn signals side mounted on the left, plus a standard signal even further left with a red arrow. Under the all arrow signal is a sign that says "LEFT TURN ON LEFT ARROW ONLY"  :crazy:

https://maps.app.goo.gl/SqpUMFBdo4BJ5bRj6
Newark born, Richmond bred

tolbs17

Aren't these signals supposed to be pointing on an angle to the left and not directly to the left? Just a flaw for me. I think VDOT needs to learn how to use signals on the diverging diamond interchanges.

https://www.google.com/maps/@38.4197624,-77.4221029,3a,31.3y,332.37h,96.58t/data=!3m6!1e1!3m4!1sHMz8dV2JvbgvUc3AIpBgJA!2e0!7i16384!8i8192

Here, you have a solid green light as opposed to a straight arrow.

https://www.google.com/maps/@38.4197643,-77.42117,3a,20y,281.76h,91.48t/data=!3m6!1e1!3m4!1sleEqInLghqOaoD0nSwjiHg!2e0!7i16384!8i8192


SkyPesos

Quote from: tolbs17 on December 16, 2021, 06:46:39 PM
Aren't these signals supposed to be pointing on an angle to the left and not directly to the left? Just a flaw for me. I think VDOT needs to learn how to use signals on the diverging diamond interchanges.

https://www.google.com/maps/@38.4197624,-77.4221029,3a,31.3y,332.37h,96.58t/data=!3m6!1e1!3m4!1sHMz8dV2JvbgvUc3AIpBgJA!2e0!7i16384!8i8192

Here, you have a solid green light as opposed to a straight arrow.

https://www.google.com/maps/@38.4197643,-77.42117,3a,20y,281.76h,91.48t/data=!3m6!1e1!3m4!1sleEqInLghqOaoD0nSwjiHg!2e0!7i16384!8i8192
I don't think it really matters. I've seen both examples both ways.

tolbs17

Quote from: SkyPesos on December 16, 2021, 06:50:28 PM
Quote from: tolbs17 on December 16, 2021, 06:46:39 PM
Aren't these signals supposed to be pointing on an angle to the left and not directly to the left? Just a flaw for me. I think VDOT needs to learn how to use signals on the diverging diamond interchanges.

https://www.google.com/maps/@38.4197624,-77.4221029,3a,31.3y,332.37h,96.58t/data=!3m6!1e1!3m4!1sHMz8dV2JvbgvUc3AIpBgJA!2e0!7i16384!8i8192

Here, you have a solid green light as opposed to a straight arrow.

https://www.google.com/maps/@38.4197643,-77.42117,3a,20y,281.76h,91.48t/data=!3m6!1e1!3m4!1sleEqInLghqOaoD0nSwjiHg!2e0!7i16384!8i8192
I don't think it really matters. I've seen both examples both ways.
Alright, just something that I noticed different and is why I asked.

plain

Quote from: tolbs17 on December 16, 2021, 06:46:39 PM
Aren't these signals supposed to be pointing on an angle to the left and not directly to the left? Just a flaw for me. I think VDOT needs to learn how to use signals on the diverging diamond interchanges.

https://www.google.com/maps/@38.4197624,-77.4221029,3a,31.3y,332.37h,96.58t/data=!3m6!1e1!3m4!1sHMz8dV2JvbgvUc3AIpBgJA!2e0!7i16384!8i8192

Here, you have a solid green light as opposed to a straight arrow.

https://www.google.com/maps/@38.4197643,-77.42117,3a,20y,281.76h,91.48t/data=!3m6!1e1!3m4!1sleEqInLghqOaoD0nSwjiHg!2e0!7i16384!8i8192

Looks fine to me.

Here's what the signal on the other side of the interstate looks like.

https://maps.app.goo.gl/pnW3DBUptyZXWLpV9

I wouldn't slant the signals too much as the motorists in SR 630's lanes might mistake them for their movement.



The VDOT districts, while all the same agency, sometimes have minor differences with certain things. Traffic signals is one of them. For example, NOVA almost always use cap visors while the rest of the state for the most part uses tunnel visors.

Compare that Stafford DDI with the one on I-66 at US 15

https://maps.app.goo.gl/gQeDqEvM7k1nmscu8


And I-64, also at US 15

https://maps.app.goo.gl/fjFaZU5rHtYJq9Jx8
Newark born, Richmond bred

SignBridge

I agree that's a sloppy installation. The arrows should mimic the approx. angle of the roadway. I'm not sure if that's in the Manual but it certainly would be good practice.

roadfro

I see nothing wrong with using either a 90° left arrow or a diagonal arrow for these DDI off-ramps. Ultimately, it's a left turn, so to me it makes more sense for the hard left arrow despite that the turn might be a bit more sweeping.
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.

mrsman

Quote from: roadfro on December 12, 2021, 04:20:33 PM
Quote from: STLmapboy on December 09, 2021, 12:00:25 AM
Quote from: jakeroot on December 08, 2021, 12:23:42 PM
Here's an inquiry for roadfro, if he sees it:

In Reno, NV, I noticed the double right turn from Neil Rd to southbound 395/580 freeway is a "yield". Not too weird, but after checking out historic street view, I noticed that there were plans to signalize this movement. Note in this image from July 2011, there is an inactive vehicular signal on the far side of the intersection, and two pedestrian signals on either side of the crosswalk. One month later, the pedestrian signals remain but the vehicular signals have been removed. At some point thereafter, the pedestrian signals in the island were modified to only have two brackets and the extra pedestrian signal removed, and the far side of the crosswalk had its pedestrian signal removed although there is physical evidence of its existence. All the while, the stop line (instead of sharks teeth) remains across the slip lane, as though there were a signal or stop condition for this movement.

So, as to the point: any idea why they decided against signalizing this movement? I can usually understand not wanting a signalized double right turn via a slip lane opposite a permissive left turn, but the left turn onto the on-ramp is protected-only. In addition, to the best of my knowledge, Nevada doesn't use double right turn yields often, if much at all (perhaps very rare?), so this seems like an odd setup.

Some pictures for reference:

The double right turn as it appears today:


Neil Rd at 395/580 Fwy -- March 2021 by Jacob Root, on Flickr

As it appeared in the summer of 2011:


Neil Rd at 395/580 Fwy -- July 2011 by Jacob Root, on Flickr

Interesting. I looked at the 2007 GSV from 580 and it seems to indicate that the inactive right-turn signal which was removed in 2011 was there four years before.

I'm not entirely certain... But I think I have an explanation given other contextual factors.

First some context. The area around the US 395/Neil Road interchange has long been one of the biggest and busiest commercial business districts of the Reno area. Meadowood Mall was constructed in the late 1970s as development in Reno was moving further south from downtown. Note that Virginia Street in the area is the original US 395 highway, and the freeway construction reached the half interchange at Virginia St (what's now exit 31) in 1981. A lot of the shopping centers in the area started getting developed after that, with much of it coming in the mid-late 1990s (especially all of it along Kietzke Lane, which itself was extended south from Virginia Street during the 80s. As this area built up as the main commercial shopping area of the region and a lot of new housing was being built further south, one lacking mobility element was that the half-interchange didn't allow for freeway entry to the south, so the nearest place for all of this shopping traffic to head back to the south meadows region was the interchange at Neil Road (formerly Del Monte Lane).

When I came to Reno for college in 2001, the intersection of Kietzke Lane and Neil Road was a 4-way stop. This all-way stop would often have long back-ups on Kietzke for those coming from retail areas to the north trying to access US 395 south. By Historic Aerials imagery, the intersection was converted to a roundabout somewhere between 2006 and 2010 (based on the StreetView STLmapboy found, the roundabout was likely completed in 2007). Part of the reason for the roundabout construction was to make the southbound left turn from Kietzke to eastbound Neil the predominant movement, and the dual right turn lane from Neil Road to US 395 south was constructed simultaneously with the roundabout. I can't recall for sure (I've always lived in northern Reno, so never had much occasion to use this movement), but I'm fairly certain that the dual right turn was fully signalized as a protected right turn when it was initially constructed.

Keep in mind during all this time, what is now Meadowood Mall Way did not exist beyond the Best Buy. In the 2000s, the Washoe County RTC had begun planning to punch Meadowood Mall Way through under US 395 to Kietzke Lane and create a new interchange. The eventual design is what we have today–Niel Road was converted from a full diamond to a split diamond with Meadowood Mall Way, providing new circulation in the area and a more direct means for some of the retail traffic to access US 395 southbound (as well as providing some relief to the existing half diamond at Virginia). Much of Washoe County's ARRA stimulus funding went in to making this project happen, which started (I believe) in late 2009 and completed sometime in 2012–panning left from the July 2011 street view jakeroot linked, you can see construction on the southbound off ramp and its conversion to frontage road in the distance. 

So with that context, my assumption is that the Meadowood Mall interchange and new southbound frontage road linking to Neil Road was expected to cause traffic patterns to shift considerably, resulting in less demand for this movement to US 395 south. Given the reduced demand for this movement, I would assume they thought it prudent to remove the signalization for this turn, but didn't think it would be a big deal to leave the striping unchanged. It does result in one of the few dual right turn lane situations in Nevada that I'm aware of that is not signalized.

Thank you for that thorough explanation!

I would add, that IMO, the primary reason to signalize this right turn would be pedestrian safety.  If there are sufficient numbers of pedestrians that would walk along the Neil Rd sidewalk and would continue walking under 580, a dedicated pedestrian phase would increase pedestrian safety.  It would seem though, that there aren't many walking here, so the dedicated signal was discarded.

I think that the roundabout also comes into play here.  You certainly wouldn't want a long red for this right turn movement that would likely cause back ups in the roundabout.  So unless the pedestrian safety issue is prominent, a restricted right turn would cause backups, and that should be avoided.

If NDOT decides to revisit signalization here, I believe they should consider a 4-aspect FYA right turn signal.  Green arrow for protected movements, generally when Neil Rd EB has the green signal indication.  Red arrow when right turn would not be allowed (generally for pedestrian crossing).  Flashing yellow arrow for the general yield movement, when westbound lefts from Neil or traffic from the service road have the right of way (and no pedestrians are crossing). 



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