Roundabouts with odd layouts and markings

Started by jakeroot, February 10, 2019, 02:16:55 AM

Previous topic - Next topic

jakeroot

I did a brief search that didn't turn up any results.

We've had a thread (or two) in the past about strange markings, but I wanted to make a thread dedicated to roundabout designs and markings, specifically those that are marked oddly or perhaps uniquely. Not uniquely bad, per se. Just unique. Or odd. Good or bad.

My example is the roundabout for the northbound BC-99 ramps at 8 Ave, in White Rock. What makes it odd? The northern and southern sections of the roundabout are both striped for two lanes, but are both only fed by a single lane. The U-turn is perhaps the stranger maneuver. Two lanes for a maneuver that is basically never done. Hopefully traffic doesn't briefly make itself into two lanes for the on-ramp, since there's only one lane leaving the roundabout in that direction (though with that much offset, hopefully it would be assumed that only the outside lane would enter the freeway, though tire marks clearly indicate that no one follows that rule).



1995hoo

The roundabout on US-15 in Maryland is a little weird in that way. Both US-15 and the other road there are two-lane roads, except that Route 15 widens to four lanes just before the roundabout in each direction (narrowing back down on the far side) and the two sides of the roundabout that carry thru traffic on Route 15 have two lanes, while the other sides have one. I've never heard anything about why it's configured this way, but I will admit that I've taken advantage of the two-lane configuration to get past slower drivers.

https://goo.gl/maps/ukhKpJwB4Au
"You know, you never have a guaranteed spot until you have a spot guaranteed."
—Olaf Kolzig, as quoted in the Washington Times on March 28, 2003,
commenting on the Capitals clinching a playoff spot.

"That sounded stupid, didn't it?"
—Kolzig, to the same reporter a few seconds later.

jakeroot

Quote from: 1995hoo on February 10, 2019, 11:37:44 AM
The roundabout on US-15 in Maryland is a little weird in that way. Both US-15 and the other road there are two-lane roads, except that Route 15 widens to four lanes just before the roundabout in each direction (narrowing back down on the far side) and the two sides of the roundabout that carry thru traffic on Route 15 have two lanes, while the other sides have one. I've never heard anything about why it's configured this way, but I will admit that I've taken advantage of the two-lane configuration to get past slower drivers.

https://goo.gl/maps/ukhKpJwB4Au

I've seen this done a few other times. Seems to be done for one of three reasons: future widening, to facilitate a double left turn off the side street, or to maximize the capacity of those entry legs. That last one is hard to explain; if one or more entries constantly dominate the roundabout, the other legs need multi-lane entries to maximize the capacity for crossing in-between gaps.

Here's an example where it was done to facilitate a double left (Duvall, WA):


kphoger

Isn't it fairly common for lanes to be added just upstream and downstream of an intersection in order to increase the number of vehicles that can pass through?  I see it at stop signs and stoplights all the time, so I don't see how a roundabout is much different in that regard.
Keep right except to pass.  Yes.  You.
Visit scenic Orleans County, NY!
Male pronouns, please.

Quote from: Philip K. DickIf you can control the meaning of words, you can control the people who must use them.

jakeroot

Quote from: kphoger on February 11, 2019, 02:33:02 PM
Isn't it fairly common for lanes to be added just upstream and downstream of an intersection in order to increase the number of vehicles that can pass through?  I see it at stop signs and stoplights all the time, so I don't see how a roundabout is much different in that regard.

Yes, though I see it at roundabouts more than other intersections.

To be clear, my intent with this thread wasn't to index roundabouts that are wider than the preceding roads. Rather, roundabouts that have odd markings or strange layouts that don't make sense.

Here's an example of another roundabout in WA with odd markings. It has been gone for a while, but the U-turn maneuvers (which served virtually no purpose until the other legs were built) were marked with two lanes. The final roundabout eventually striped those sections as one lane.


kphoger

Probably just seemed like a good idea at the time of construction to plan that way just in case.
Keep right except to pass.  Yes.  You.
Visit scenic Orleans County, NY!
Male pronouns, please.

Quote from: Philip K. DickIf you can control the meaning of words, you can control the people who must use them.

riiga


jakeroot

Quote from: kphoger on February 11, 2019, 03:39:27 PM
Probably just seemed like a good idea at the time of construction to plan that way just in case.

No doubt. Though other variations that I've seen usually only stripe one lane, or none, if there's no logical use for those sections of roundabout.

Quote from: riiga on February 11, 2019, 04:30:24 PM
Looks perfectly normal to me and not that different from this:
https://i.imgur.com/JVeWjwx.png

My example from BC certainly looks more European than North American, though at least your example has a use for all sections of the roundabout. Are there any two-lane-striped U-turn roundabouts in Sweden (like those at off-ramps)?

UCFKnights

Quote from: jakeroot on February 11, 2019, 03:17:22 PM
Quote from: kphoger on February 11, 2019, 02:33:02 PM
Isn't it fairly common for lanes to be added just upstream and downstream of an intersection in order to increase the number of vehicles that can pass through?  I see it at stop signs and stoplights all the time, so I don't see how a roundabout is much different in that regard.

Yes, though I see it at roundabouts more than other intersections.

To be clear, my intent with this thread wasn't to index roundabouts that are wider than the preceding roads. Rather, roundabouts that have odd markings or strange layouts that don't make sense.

Here's an example of another roundabout in WA with odd markings. It has been gone for a while, but the U-turn maneuvers (which served virtually no purpose until the other legs were built) were marked with two lanes. The final roundabout eventually striped those sections as one lane.


I feel like around here, roads tend to narrow before roundabouts (unless there is special bypass lanes or whatnot), which kind of makes sense, as roundabouts seem to provide the most actual benefits in the single lane format (see the other thread for the problems of multi-lane round abouts). I'm kind of curious, are any built for a 2 lane width but striped for a single lane, which I know is extremely common on other intersections (especially traffic signals)

jakeroot

#9
Quote from: UCFKnights on February 11, 2019, 05:50:51 PM
I'm kind of curious, are any built for a 2 lane width but striped for a single lane, which I know is extremely common on other intersections (especially traffic signals)

This roundabout in East Lansing, Michigan is striped for one lane, but is two lanes wide.


roadfro

Quote from: jakeroot on February 11, 2019, 03:17:22 PM
Here's an example of another roundabout in WA with odd markings. It has been gone for a while, but the U-turn maneuvers (which served virtually no purpose until the other legs were built) were marked with two lanes. The final roundabout eventually striped those sections as one lane.



The final markings still have some oddities, coming from Main St to take a left onto Martin Rd. The striping pattern in the middle has an unnatural curve pattern for this movement, and they didn't break the interior lane line for through movement northwestbound on Martin Rd. So these left turns are not properly guided into one of the circulating lanes. (Granted this might not be a big issue at present because Main St doesn't appear to be a very "main" street–doesn't go very far and has nothing on it, according to current GMaps satellite imagery.)
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.

AsphaltPlanet

I used to work for an engineering company that had a fair amount of experience building roundabouts.  It was there general practice to build roundabouts for ultimate traffic conditions rather than interim traffic conditions because it was both difficult and disruptive to go back in to add a lane to roundabout after it had opened to traffic.

This is less true for signalized intersections.  Although many signal controlled intersections widen out with additional lanes through the intersection, this is generally done to minimize the length of queued traffic rather than for future construct-ability issues.

That's what I garnered from the company I used to work for at least.
AsphaltPlanet.ca  Youtube -- Opinions expressed reflect the viewpoints of others.

kphoger

Quote from: jakeroot on February 11, 2019, 11:57:21 PM
This roundabout in East Lansing, Michigan is striped for one lane



Except where it isn't.   ;-)
Keep right except to pass.  Yes.  You.
Visit scenic Orleans County, NY!
Male pronouns, please.

Quote from: Philip K. DickIf you can control the meaning of words, you can control the people who must use them.

jakeroot

Quote from: roadfro on February 12, 2019, 11:29:46 AM
Quote from: jakeroot on February 11, 2019, 03:17:22 PM
Here's an example of another roundabout in WA with odd markings. It has been gone for a while, but the U-turn maneuvers (which served virtually no purpose until the other legs were built) were marked with two lanes. The final roundabout eventually striped those sections as one lane.



The final markings still have some oddities, coming from Main St to take a left onto Martin Rd. The striping pattern in the middle has an unnatural curve pattern for this movement, and they didn't break the interior lane line for through movement northwestbound on Martin Rd. So these left turns are not properly guided into one of the circulating lanes. (Granted this might not be a big issue at present because Main St doesn't appear to be a very "main" street–doesn't go very far and has nothing on it, according to current GMaps satellite imagery.)

The final markings seem to have a dashed section to allow left-turning cars to access Main Street. Unless I'm seeing it wrong. Main Street does have two lanes but is only fed by one lane. There may be plans for a fourth leg, maybe. Main Street is still closed, though. The road was built but remains closed until development proceeds with a large shopping center.

jakeroot

Quote from: kphoger on February 12, 2019, 01:22:24 PM
Quote from: jakeroot on February 11, 2019, 11:57:21 PM
This roundabout in East Lansing, Michigan is striped for one lane

https://www.bk-ecosys.be/wp-content/uploads/2017/01/figure-4-61-marsh-hamilton.jpg

Except where it isn't.   ;-)

You know, I was actually going to put a disclaimer about that. But I didn't think anyone would actually say anything. Thanks for proving me wrong, I guess! :-D




Quote from: AsphaltPlanet on February 12, 2019, 11:49:27 AM
I used to work for an engineering company that had a fair amount of experience building roundabouts.  It was there general practice to build roundabouts for ultimate traffic conditions rather than interim traffic conditions because it was both difficult and disruptive to go back in to add a lane to roundabout after it had opened to traffic.

This is less true for signalized intersections.  Although many signal controlled intersections widen out with additional lanes through the intersection, this is generally done to minimize the length of queued traffic rather than for future construct-ability issues.

That's what I garnered from the company I used to work for at least.

Totally makes sense to me. I was just surprised to see at least a few roundabouts in my area that had striping that didn't match the actual configuration.

Elm

There's a sized-for-two-striped-for-one roundabout at South Golden Rd and Ulysses St in Golden, CO (map). It was built around '99 with the three roundabouts to the west, and they were all sized for two through lanes each way, but the city apparently left that one as a single-lane roundabout since the north, south, and east approaches had one lane. Further east, the more recently added roundabouts at Moss and Quaker Streets are single-laned but pretty spacious. The one at Moss in particular seems to have extra room to make changes in the future.

In Colorado Springs, there are three single lane roundabouts on an otherwise four lane section of Chapel Hills Dr, between Briargate Pkwy and Old Ranch Rd (middle roundabout). There's space for a second lane in the roundabouts, but the lanes technically merge before each one; there are extra curbs at the southern roundabout for physical enforcement

Further north in the Springs, there's a former roundabout intersection (map) that appears to be a work in progress generally; I first noticed it as a vaguely roundabout-shaped but mostly featureless area of asphalt in Google Maps. This seems to be the path it's taken (going by Google Earth):

  • Initially built as a three-legged, single lane roundabout: Stout Rd from the east road has four lanes and narrows near roundabout, and all legs might be two-way roads.
  • The western and southern legs are reconfigured into a two lane, one-way loop; the roundabout stays single-lane.
  • A two-way northern leg is added to the roundabout to access another lot.
  • The roundabout is removed, leaving a vaguely roundabout-shaped area of asphalt; four continuous lanes are maintained around the intersection between the loop and the eastern Stout Rd.

jakeroot

^^
Great list, Elm. Thanks for bringing those up. Colorado has quite a history of some odd roundabouts. The CO-82 roundabout in Aspen (built in 1999) was also built for two lanes of traffic, but two of the sections are currently only used by one lane. One of the sections was (in the last few years) narrowed a bit with markings, but the other section was not. There's also multiple roundabouts in Avon that have no markings at all (eg. here and here), several of which are, again, two lanes wide but fed by only one lane.

Those in Golden that you've pointed out are certainly strange, particularly the multi-lane ones that seem to utilize a form of concentric markings that are not typically used at "modern roundabouts"...I've highlighted the issue on the image below:


kphoger

They're dotted lines rather than dashed, so it looks like they're for guiding drivers to stay in the correct lane.

I'm not in favor, though, as it somewhat discourages exiting from the second lane.
Keep right except to pass.  Yes.  You.
Visit scenic Orleans County, NY!
Male pronouns, please.

Quote from: Philip K. DickIf you can control the meaning of words, you can control the people who must use them.

abefroman329

While preparing to drive in the UK for the first time, I was reading up on the rules of the road, and noticed that it's the law that, when entering the roundabout, the outermost lane is for vehicles making the next exit from the roundabout, and vehicles making subsequent exits need to use the lanes closer to the center of the roundabout.  Given that that's not common knowledge, it seems like it'd be a good idea to have lane markings throughout the roundabout.

kphoger

Quote from: abefroman329 on February 14, 2019, 12:48:59 PM
While preparing to drive in the UK for the first time, I was reading up on the rules of the road, and noticed that it's the law that, when entering the roundabout, the outermost lane is for vehicles making the next exit from the roundabout, and vehicles making subsequent exits need to use the lanes closer to the center of the roundabout.  Given that that's not common knowledge, it seems like it'd be a good idea to have lane markings throughout the roundabout.

Can't go straight through from the outer lane, eh?  Interesting.
Keep right except to pass.  Yes.  You.
Visit scenic Orleans County, NY!
Male pronouns, please.

Quote from: Philip K. DickIf you can control the meaning of words, you can control the people who must use them.

jakeroot

Quote from: abefroman329 on February 14, 2019, 12:48:59 PM
While preparing to drive in the UK for the first time, I was reading up on the rules of the road, and noticed that it's the law that, when entering the roundabout, the outermost lane is for vehicles making the next exit from the roundabout, and vehicles making subsequent exits need to use the lanes closer to the center of the roundabout.  Given that that's not common knowledge, it seems like it'd be a good idea to have lane markings throughout the roundabout.

It's not any different in the US, even at signalized intersections. Pretty much every state requires you to turn left or right from the respective edge of the roadway, unless otherwise directed. At roundabouts with double left turns, that's the "otherwise directed" situation.

We need to stop thinking of roundabouts as being a one-way road with several exits. All it is, is a round-shaped intersection where left turns intentionally overlap and where those who arrived first, have priority first. Thinking of it as a one-way road, in our head, makes us think that the right lane has absolutely authority over the left lanes, and those in that lane may endlessly proceed around the circle. When in fact, the right lane should never do anything other than go straight or turn right (unless an arrow says that the right lane can go left).

Quote from: kphoger on February 14, 2019, 12:33:40 PM
They're dotted lines rather than dashed, so it looks like they're for guiding drivers to stay in the correct lane.

I'm not in favor, though, as it somewhat discourages exiting from the second lane.

Perhaps they're guiding the left lane to the next exit, but they're also (unintentionally) telling the right lane that they can continue left as well.

Note that at this roundabout (and at most), the dashed lines only point to the exit. This tells the right lane that they cannot continue around (but is dashed because cars entering from the right will be crossing over it):



Frankly, I'm not necessarily in favor of markings in roundabouts at all. Europe widely uses a single dashed line that goes around the entire circle, but that's only to tell traffic that there's two lanes. They don't take the lines seriously like we do (where most North Americans would think that changing to the outer lane would be required to exit).

jakeroot

As an example of this last fact, note this roundabout in Gig Harbor, WA (which was later modified in 2007, about 8 years after construction). It was built with modern intentions, but originally used concentric markings (single dashed line all the way around). Drivers barely used the inside lane because they felt like it was a giant one-way road where exiting was only allowed from the outer lane. The tire marks (which I've circled) clearly show that drivers illegally continued around the circle from the right lane:


riiga

Quote from: jakeroot on February 11, 2019, 05:19:46 PM
Are there any two-lane-striped U-turn roundabouts in Sweden (like those at off-ramps)?

I can't think of any that I know, but there could be. At off-ramps (especially leading from diamond interchanges or similar configurations) roundabouts are often replaced by the teardrop (dogbone?) design rather than two full roundabouts.

MCRoads

Quote from: riiga on February 16, 2019, 05:36:35 PM
Quote from: jakeroot on February 11, 2019, 05:19:46 PM
Are there any two-lane-striped U-turn roundabouts in Sweden (like those at off-ramps)?

I can't think of any that I know, but there could be. At off-ramps (especially leading from diamond interchanges or similar configurations) roundabouts are often replaced by the teardrop (dogbone?) design rather than two full roundabouts.

I would say those are normal, they are just one, long skinny roundabout. What I find unusual is when those same interchanges have full roundabouts on both sides. there are some exceptions to where this is acceptable, but not many.
I build roads on Minecraft. Like, really good roads.
Interstates traveled:
4/5/10*/11**/12**/15/25*/29*/35(E/W[TX])/40*/44**/49(LA**)/55*/64**/65/66*/70°/71*76(PA*,CO*)/78*°/80*/95°/99(PA**,NY**)

*/** indicates a terminus/termini being traveled
° Indicates a gap (I.E Breezwood, PA.)

more room plz

english si

Quote from: abefroman329 on February 14, 2019, 12:48:59 PMWhile preparing to drive in the UK for the first time, I was reading up on the rules of the road, and noticed that it's the law that, when entering the roundabout, the outermost lane is for vehicles making the next exit from the roundabout, and vehicles making subsequent exits need to use the lanes closer to the center of the roundabout.
On entering, yes, sort of - but you can go straight on at a 4-arm roundabout in the outermost lane throughout if that's what makes sense. And you can leave from inner lanes (though on larger/busier roundabouts you might want to move over on approach), rather than having to move over because your exit is next. Plus it's not law (just a rule) as there's no 'MUST' about it.

https://www.highwaycodeuk.co.uk/roundabouts.html

Quote186
Signals and position. When taking the first exit, unless signs or markings indicate otherwise

signal left and approach in the left-hand lane
keep to the left on the roundabout and continue signalling left to leave.

When taking an exit to the right or going full circle, unless signs or markings indicate otherwise
signal right and approach in the right-hand lane
keep to the right on the roundabout until you need to change lanes to exit the roundabout
signal left after you have passed the exit before the one you want.

When taking any intermediate exit, unless signs or markings indicate otherwise
select the appropriate lane on approach to and on the roundabout
you should not normally need to signal on approach
stay in this lane until you need to alter course to exit the roundabout
signal left after you have passed the exit before the one you want.

When there are more than three lanes at the entrance to a roundabout, use the most appropriate lane on approach and through it.

Interestingly, spiral roundabouts (normally a large roundabout at a freeway junction, with traffic signals) have lots of markings and signs (and even different colour surfaces on occasion) to get you to move out, whereas regular ones often have no lane markings on the actual roundabout



Opinions expressed here on belong solely to the poster and do not represent or reflect the opinions or beliefs of AARoads, its creators and/or associates.