Multiple traffic signals on road

[roadman65]

When Illinois does go minimalist, this is what it looks like: 
https://goo.gl/maps/ihYjY2skout

If you want two signals for the left turn movement, and two signals for the straight movement, just put two 5-section heads up and you're done!  2 signals for 2 lanes, and 2 for each movement.  Done.  (You don't even need the 3-section head in the back, but IDOT puts those on all their cable-suspended signals anyway.  Even though they're usually useless.)

I wouldn't say that the near-side signals are useless.  It helps motorists approaching the intersection see what color the signal is; especially if there's a large vehicle in the queue.  I'd agree that a 5 section tower would be overkill, but not a basic 3 section one.

Agreed, that is why I hate Florida's (and other states that literally follow the MUTCD) as you get a truck in front of you and you are blind to the signal's orientation.

[jakeroot]

While reading the British Columbia Signal Design Manual, I stumbled upon ~ 402.6.4, which covers where signals shall be placed. I found it rather interesting. While protected/permissive left turns need only two signal heads, protected-only left turns shall have at least three signal heads, if not more (dual turn lanes, for example). The signals shall be mounted as follows...

- One primary head shall be located in the far side raised median mounted at a height of 2.5m.
- One secondary head shall be located at the far left side of the intersection at a height of 2.5 m.
- One auxiliary head shall be located in the near side median mounted at a height of 1.25 m.
- If there is no raised median, then the primary head shall be mounted overhead on the signal pole arm. If there are no raised medians, the auxiliary head cannot be installed.

AFAICT, no overhead signals are required, lest the median is too narrow to accommodate a signal head.

Here's an example of a properly-signalized left turn in BC. This is Hwy 19 at Willis Road, near Campbell River (this also happens to be the same intersection where Kimberly Corman holds up traffic after her premonition of the huge pile-up in Final Destination 2).

Note the three left turn signals. One at the stop line, another in the far center median, and another on the left edge:

[SignBridge]

I wonder how often those median/post-mounted signals get knocked down in accidents. This type of mounting used to be common in California too, but most have been replaced by mounting on a longer mast-arm. I remember especially seeing that on El Camino Real (S.R.82) between San Francisco and San Jose.

[paulthemapguy]

I wonder how often those median/post-mounted signals get knocked down in accidents. This type of mounting used to be common in California too, but most have been replaced by mounting on a longer mast-arm. I remember especially seeing that on El Camino Real (S.R.82) between San Francisco and San Jose.

You know those white signs that show the diagram of an arrow dodging to the right of a median (R4-7)?
http://mutcd.fhwa.dot.gov/htm/2009/part2/fig2b_10_longdesc.htm

I maintain the signs for a certain road district, and these signs get knocked over constantly.  Some of them we can hardly keep standing because they get trashed so frequently.  I can't imagine the damages (cost) of having to constantly replace a signal on the median, especially on a truck route.

[SignBridge]

That might be the reason California changed to the long mast-arm mounting.

[roadfro]

^ While the median pole-mounted left turn signal wasn't widespread in Nevada, it was employed in a few locations.

City of Las Vegas eventually removed one such installation in the median on Charleston Blvd at Valley View Blvd, replacing with a longer mast arm and putting the left turn signals overhead. This is a busy intersection and the medians were very narrow, so the signals were knocked down often.


The only median mounted left turn signals that I can think of in Nevada now are at intersections with an extremely wide median island, such that the odds of knockdown are drastically reduced.

[mrsman]

That might be the reason California changed to the long mast-arm mounting.

Yes.  And don't forget that the older mast arms just could not be extended as far as they can today.  Many old installations will have guy-wire mast arms.  So the only way to hook up a left turn arrow is by the median, or perhaps a guy-wire from the left side of the street.

[jakeroot]

Wisconsin employs 1.5 meter-high median-mounted signals at nearly every intersection, though some newer, wider intersections use the more typical mast-arms. I'm not sure how often Wisconsin runs into trouble with their median-mounted signals (I would guess not often, given how often they're used), but I haven't noticed any glaring issues in BC with the signals or signs in the median being knocked over at an alarming basis.

If the reason that California and Nevada abandoned their median-mounted signals was due to the frequency of collisions involving them, they simply need(ed) to set the median back from the turning circle of left-turning traffic. Take for example these nearly identical intersections, the first from BC, the second from Nevada (note that in the BC example, the median-mounted signals face traffic on the near-side -- the far-side median is simply too far away for the signal to be of any use):

[roadfro]

Wisconsin employs 1.5 meter-high median-mounted signals at nearly every intersection, though some newer, wider intersections use the more typical mast-arms. I'm not sure how often Wisconsin runs into trouble with their median-mounted signals (I would guess not often, given how often they're used), but I haven't noticed any glaring issues in BC with the signals or signs in the median being knocked over at an alarming basis.

If the reason that California and Nevada abandoned their median-mounted signals was due to the frequency of collisions involving them, they simply need(ed) to set the median back from the turning circle of left-turning traffic. Take for example these nearly identical intersections, the first from BC, the second from Nevada (note that in the BC example, the median-mounted signals face traffic on the near-side -- the far-side median is simply too far away for the signal to be of any use):

Curious where that Nevada intersection is...

Like I said, there weren't a whole lot of these median mounted signals in Nevada to begin with–much more common in California. The couple I did know of were replaced because of knock downs.

I think the current Nevada preference is to have all primary signals overhead wherever feasible, as this helps somewhat with visibility. Longer mast arms being common now and less potential for knockdowns make this easier to achieve.

[jakeroot]

Curious where that Nevada intersection is...

https://goo.gl/mgmNdi

This is the BC intersection: https://goo.gl/nVH8H0 (note that the GSV is out of date, and does not show the current setup, which was changed due to a SkyTrain extension).

Like I said, there weren't a whole lot of these median mounted signals in Nevada to begin with–much more common in California. The couple I did know of were replaced because of knock downs.

I think the current Nevada preference is to have all primary signals overhead wherever feasible, as this helps somewhat with visibility. Longer mast arms being common now and less potential for knockdowns make this easier to achieve.

I'm certainly happy to see the longer mast arms in place, but I hope we don't get carried away with placing signals only on the far side of the intersection. Near-side signals have their use as well, be them median-mounted or sidewalk-mounted.

[JMAN_WiS&S]

Wisconsin employs 1.5 meter-high median-mounted signals at nearly every intersection, though some newer, wider intersections use the more typical mast-arms. I'm not sure how often Wisconsin runs into trouble with their median-mounted signals (I would guess not often, given how often they're used), but I haven't noticed any glaring issues in BC with the signals or signs in the median being knocked over at an alarming basis.

If the reason that California and Nevada abandoned their median-mounted signals was due to the frequency of collisions involving them, they simply need(ed) to set the median back from the turning circle of left-turning traffic. Take for example these nearly identical intersections, the first from BC, the second from Nevada (note that in the BC example, the median-mounted signals face traffic on the near-side -- the far-side median is simply too far away for the signal to be of any use):

One thing I am not fond of is how median mounted monotube mast arms in Wisconsin are starting to become really popular. Personally, I only like them to come out of the ground on the right and go to the left, not start in the median.

[paulthemapguy]

One thing I am not fond of is how median mounted monotube mast arms in Wisconsin are starting to become really popular. Personally, I only like them to come out of the ground on the right and go to the left, not start in the median.

Yes.  And as stated earlier, putting signals in the median makes them very susceptible to collisions.  You don't want to INCREASE the property value of things on the median, where stuff gets crashed into all the time!   

[jakeroot]

One thing I am not fond of is how median mounted monotube mast arms in Wisconsin are starting to become really popular. Personally, I only like them to come out of the ground on the right and go to the left, not start in the median.

Yes.  And as stated earlier, putting signals in the median makes them very susceptible to collisions.  You don't want to INCREASE the property value of things on the median, where stuff gets crashed into all the time!   

As I also stated earlier, you can seriously reduce the chance of collisions by setting back the medians from the intersections. British Columbia figured it out .. I'm not sure why the US hasn't yet. Pulling the median right up the crosswalk puts it the left turn path overlap, where I agree, it is very susceptible to impact.

[mrsman]

One thing I am not fond of is how median mounted monotube mast arms in Wisconsin are starting to become really popular. Personally, I only like them to come out of the ground on the right and go to the left, not start in the median.

Yes.  And as stated earlier, putting signals in the median makes them very susceptible to collisions.  You don't want to INCREASE the property value of things on the median, where stuff gets crashed into all the time!   

As I also stated earlier, you can seriously reduce the chance of collisions by setting back the medians from the intersections. British Columbia figured it out .. I'm not sure why the US hasn't yet. Pulling the median right up the crosswalk puts it the left turn path overlap, where I agree, it is very susceptible to impact.

And in some cases, the median goes even beyond the crosswalk all the way to the intersection itself:

https://www.google.com/maps/@39.0415492,-77.0517865,3a,75y,244.83h,73.98t/data=!3m7!1e1!3m5!1s_91r5oSjcI5o3yJ1jTawlQ!2e0!6s%2F%2Fgeo2.ggpht.com%2Fcbk%3Fpanoid%3D_91r5oSjcI5o3yJ1jTawlQ%26output%3Dthumbnail%26cb_client%3Dmaps_sv.tactile.gps%26thumb%3D2%26w%3D203%26h%3D100%26yaw%3D29.992403%26pitch%3D0!7i13312!8i6656

Here, (corner of Georgia and University in Wheaton, MD), we have a narrow median.  The crosswalk goes through the median.  Ramps are provided for disabled people crossing.  I guess the traffic engineers thought that it would  be nice to have a pedestrian refuge, but this median is way too narrow for that.  Bettter not to give a false sense of security and not provide any waiting area at all.

[JMAN_WiS&S]

One thing I am not fond of is how median mounted monotube mast arms in Wisconsin are starting to become really popular. Personally, I only like them to come out of the ground on the right and go to the left, not start in the median.

Yes.  And as stated earlier, putting signals in the median makes them very susceptible to collisions.  You don't want to INCREASE the property value of things on the median, where stuff gets crashed into all the time!   

I am perfectly fine withe putting pedistall mount signals and lighting in the median, just not mast arm bases. If I recall correctly, wisdot uses tapco breakaway bases so they aren't that hard to replace when hit.

[jeffandnicole]

One thing I am not fond of is how median mounted monotube mast arms in Wisconsin are starting to become really popular. Personally, I only like them to come out of the ground on the right and go to the left, not start in the median.

Yes.  And as stated earlier, putting signals in the median makes them very susceptible to collisions.  You don't want to INCREASE the property value of things on the median, where stuff gets crashed into all the time!   

I am perfectly fine withe putting pedistall mount signals and lighting in the median, just not mast arm bases. If I recall correctly, wisdot uses tapco breakaway bases so they aren't that hard to replace when hit.

Just gotta know how to protect them! 

https://goo.gl/maps/CuYzpCtqXPt

https://goo.gl/maps/bCCro1ph3iu

Although, they have taken them out and done a more standard design if an intersection is going to be reconstructed... https://goo.gl/maps/J1oad7uNQem

[SignBridge]

J&N, I've noticed many of those longer straight mast-arms that NJDOT has put in especially on US 1 in the Princeton area have started to bend downward, indicating to me a poor quality installation.

[paulthemapguy]

Just gotta know how to protect them! 

https://goo.gl/maps/CuYzpCtqXPt

https://goo.gl/maps/bCCro1ph3iu

Although, they have taken them out and done a more standard design if an intersection is going to be reconstructed... https://goo.gl/maps/J1oad7uNQem

Those first two pictures are hilarious to me because, at a high speed, tapering the median into the ground is just going to make the illicit vehicle ramp up right into the signal head!    That's why DOT's have been phasing out the guardrail terminals that taper into the ground (at least IDOT has been doing so).  But then you showed the modern impact attenuators and everything is all good haha

[jeffandnicole]

J&N, I've noticed many of those longer straight mast-arms that NJDOT has put in especially on US 1 in the Princeton area have started to bend downward, indicating to me a poor quality installation.

It depends on the design. Some of them bend downwards intentionally. If there's one that you could see from a few years back on GSV and see a noticable difference today, it'll be interesting to see.

While most people relate NJ with the pennant mast arms, for a good 20 years NJ has been using the monopole, especially for arms over 25 feet.  Of the ones I'm familiar with, none have ever been replaced or even shown signs of fault.

[SignBridge]

Why would they be designed to bend intentionally? I thought those monotube arms are supposed to be straight. In some states, notably Nevada, they do not bend and are angled very slightly upward which looks good to me.

[peterj920]

https://www.google.com/maps/@44.0776455,-87.7076839,3a,75y,306.73h,94.51t/data=!3m6!1e1!3m4!1slNI8tDh-wAvK-YkBuR-mJw!2e0!7i13312!8i6656?hl=en

Dewey St and Rapids Rd in Manitowoc, WI.  There are 5 traffic signals for a single right turn lane.  Aside from the 4 near signals, there is another one mounted on the median of Rapids Rd.

[jakeroot]

https://www.google.com/maps/@44.0776455,-87.7076839,3a,75y,306.73h,94.51t/data=!3m6!1e1!3m4!1slNI8tDh-wAvK-YkBuR-mJw!2e0!7i13312!8i6656?hl=en

Dewey St and Rapids Rd in Manitowoc, WI.  There are 5 traffic signals for a single right turn lane.  Aside from the 4 near signals, there is another one mounted on the median of Rapids Rd.

In what part of Europe is that street view? Lol. Seriously. I wouldn't say it's overkill, but that's a lot. Is that WisDOT standard?

[cl94]

https://www.google.com/maps/@44.0776455,-87.7076839,3a,75y,306.73h,94.51t/data=!3m6!1e1!3m4!1slNI8tDh-wAvK-YkBuR-mJw!2e0!7i13312!8i6656?hl=en

Dewey St and Rapids Rd in Manitowoc, WI.  There are 5 traffic signals for a single right turn lane.  Aside from the 4 near signals, there is another one mounted on the median of Rapids Rd.

In what part of Europe is that street view? Lol. Seriously. I wouldn't say it's overkill, but that's a lot. Is that WisDOT standard?

It's overkill. The maximum I would have for the right turn is 3 due to the geometry and even that is pushing it. One could just put 2 signals for the approach and place them so they can be seen before the crosswalk, with a yield sign for the right turn.

[peterj920]

https://www.google.com/maps/@44.0776455,-87.7076839,3a,75y,306.73h,94.51t/data=!3m6!1e1!3m4!1slNI8tDh-wAvK-YkBuR-mJw!2e0!7i13312!8i6656?hl=en

Dewey St and Rapids Rd in Manitowoc, WI.  There are 5 traffic signals for a single right turn lane.  Aside from the 4 near signals, there is another one mounted on the median of Rapids Rd.

In what part of Europe is that street view? Lol. Seriously. I wouldn't say it's overkill, but that's a lot. Is that WisDOT standard?

It's the City of Manitowoc that put those lights up.  It's interesting how on North Dewey St there are 3 traffic signals for 2 northbound lanes, but there are 5 signals for a right turn from Dewey to North Rapids Rd and 4 signals for traffic turning left to head south on Rapids Rd.  There's a total of 9 signals!  Here's another perspective where you can see all 9 signals. 

https://www.google.com/maps/@44.0776455,-87.7076839,3a,75y,272.48h,88.17t/data=!3m6!1e1!3m4!1slNI8tDh-wAvK-YkBuR-mJw!2e0!7i13312!8i6656?hl=en

[jakeroot]

Beverley, England (err, the East Riding of Yorkshire) recently (late 2014) reconfigured the Grove Hill Junction (A1174/Hull Road @ Grovehill Road) so that it was no longer a roundabout. A point of contention for nearby residents is the sheer number of traffic lights: This junction, with 5 intersecting roads, has 42 traffic lights. Here's a picture to give you an idea as to the signal placement:



Image courtesy Metro.co.uk

Apparently, several months ago, the power went out, and the intersection acted as a free-flow junction. Local residents swear it performed better than it did with the lights switched on.

Here's a before shot of the junction: