I'm kinda partial to roundabouts.

May 3, 2006 4:31 PM

Advances in traffic management are slowly being recognized as superior to stoplights. (java, video, video)
posted by bigmusic (37 comments total)

posted by StrasbourgSecaucus at 4:41 PM on May 3, 2006

Of course, it might be a bit tougher to issue photo tickets at a roundabout, and the gov't does like it's money . . .
posted by JekPorkins at 4:55 PM on May 3, 2006

Err. Is there some text somewhere that explains this?
posted by jacquilynne at 4:56 PM on May 3, 2006

hhhuh.
posted by boo_radley at 5:02 PM on May 3, 2006

So the idea is that just letting everyone make their own way (a la SE Asia) is ultimately superior to the intersection model? How would this work for pedestrians in low-pedestrian zones? Also when people have been used to traffic lights for decades, is it really plausible to let them make their own way?
posted by cell divide at 5:05 PM on May 3, 2006

I don't see the superiority of any of that. I see plenty of danger, however.
posted by CRM114 at 5:13 PM on May 3, 2006

I read this article in Wired a couple years ago:

Several years ago, Monderman ripped out all the traditional instruments used by traffic engineers to influence driver behavior - traffic lights, road markings, and some pedestrian crossings - and in their place created a roundabout, or traffic circle. The circle is remarkable for what it doesn't contain: signs or signals telling drivers how fast to go, who has the right-of-way, or how to behave. There are no lane markers or curbs separating street and sidewalk, so it's unclear exactly where the car zone ends and the pedestrian zone begins. To an approaching driver, the intersection is utterly ambiguous - and that's the point.

"I love it!" Monderman says at last. "Pedestrians and cyclists used to avoid this place, but now, as you see, the cars look out for the cyclists, the cyclists look out for the pedestrians, and everyone looks out for each other. You can't expect traffic signs and street markings to encourage that sort of behavior. You have to build it into the design of the road."

To answer your question, cell divide: only if you're in Holland :)
posted by brain cloud at 5:15 PM on May 3, 2006

I think the idea is that you could automate it. You know, for when cars are driven by robots. In the future!
posted by mr_roboto at 5:16 PM on May 3, 2006

Sounds neat but incredibly impractical. (1) it is a technology that needs 100% deployment in the cars on those roads before it can be used, thus incremental roll out is difficult or impossible, (2) cars (unlike pixels on the screen) can have sudden failures and one would need an easy out for the vehicle in this case -- thus the tight packing shown would not be feasible before the margin of error is too small, and (3) this requires incredibly accurate positioning probably much better than GPS.

A more realistic solution for "AI" controlled driving would be on the highway during rush hour. One could deploy it on two lanes of the highway and leave two lanes for non-enhanced cars -- as adoption increases convert more lanes over to "AI" controlled. It would allow for closer packing of cars since the computer would be tracking internally each cars engine -- no need for the loose packing necessary to allow humans to react. It would also prevent slowdowns which are more of a chain reaction of human reaction times -- which can be mitigated by smart global optimization.

Taking it even further, it could be used to optimize on-ramp merging into traffic to prevent the current slow downs in high density traffic.

In total, the demo is cool but highly unrealistic at least for the next decade or more -- that said, there are real potential applications for this type of global optimizer in rush hour traffic situations.
posted by bhouston at 5:17 PM on May 3, 2006

yeah, i can just see how people with pickup trucks and suvs are going to not run over everyone else on the road in that scenario

it won't work ... not the way some people drive in the u s
posted by pyramid termite at 5:22 PM on May 3, 2006

Stoplights seem only to irritate people (including, yes, me). They come upon intersections and get fidgety,or pull up beside you in order to turn right even when there is no lane, etc. They seem to bring out some of the worst in human nature. People just don't like being told "no, you can't do anything for a bit here," probably more especially in hyper-individualistic America.

Coming upon lights late at night, when there may likely be hardly any other cars around, is the worst.
posted by raysmj at 5:25 PM on May 3, 2006

it won't work ... not the way some people drive in the u s

They actually change the way people drive.
posted by JekPorkins at 5:29 PM on May 3, 2006

As a driver whose daily commute includes two to three roundabouts, my opinion is that they're great for small uncrowded intersections, but in heavy traffic, they SUCK. Particularly if one of the intersecting ways has much more heavy traffic than the other. Cars heedlessly pour through in one direction, confident in their right of way; in the other direction, fuming drivers queue up, desperate for any break in the traffic.

My preferred solution is a roundabout with traffic lights. Have the traffic lights regulate travel in rush hour (whatever that is for the particular roundabout; in the case of , and switch them off outside of these times.
posted by aeschenkarnos at 5:42 PM on May 3, 2006

mr_roboto - in teh futar I will be going straight over the roundabouts in my flying car.
posted by pompomtom at 5:54 PM on May 3, 2006

Do those YouTube videos work for anyone? They just stall out for me.
posted by delmoi at 6:04 PM on May 3, 2006

Of course in the UK and Europe roundabouts are the norm and I have to say that I don't recognise some of the problems raised. Many do have filter stoplights for rush hour though.

For me driving in the US is endlessly stop-go frustrating because of the one after another intersections with stoplights. The nicest thing about a roundabout is that you can see from a distance if you need to stop and if you don't just keep going, albeit after slowing down.
posted by A189Nut at 6:34 PM on May 3, 2006

Do those YouTube videos work for anyone? They just stall out for me.

Same thing for me, but if you click on the giant YouTube links, it will open up the real YouTube page and you can watch them.

[oh, and you can beat photo ticket cameras if you go fast enough]
posted by birdherder at 6:46 PM on May 3, 2006

We have a few mini-roundabouts in Austin, Tx. People seem to like them.
posted by melt away at 7:06 PM on May 3, 2006

People around here like certainty. They seem to hate traffic circles, constantly fretting about their ability to get off of them at the right moment. Reminds me of how my parents loathe their local 4-way stop. The cooperative element, attractive to some, frustrates them. Me, I think it's great. Why wait for a green when there is absolutely no one in sight?!
posted by dreamsign at 7:41 PM on May 3, 2006

The simulation in the first link works perfectly, I suppose, but no cars are making any turns.
posted by DakotaPaul at 7:51 PM on May 3, 2006

And after finally getting the YouTube videos to work (thanks birdherder), I'd say that what what's going on in the first video could not happen here in the U.S. (or at least here in the Central Valley of California). Drivers are generally self-centered behind the wheel, distracted, and not courteous enough to let people through without a light forcing them to do so. The drivers making right turns in that video would be stuck for a long time if that happened here.
posted by DakotaPaul at 7:57 PM on May 3, 2006

every time i see transportation related links here, my brain starts clicking. i just got through working on a bibliography about roundabouts. they're going to be the next big thing in traffic engineering, or that's the plan at least.

the problem with drivers in the central valley is that they're conditioned by all the jerks in big rigs. so then they buy SUVs and the cycle continues. at least that's what i've seen along 99.
posted by kendrak at 8:27 PM on May 3, 2006

Stoplights? Who needs stoplights when you can play real-life Frogger?
posted by fandango_matt at 10:03 PM on May 3, 2006

All traffic problems can be solved by using magic roundabouts.
posted by klausness at 10:16 PM on May 3, 2006

Roundabouts work great when single-lane, and low to moderate traffic. My perception is that they aren't very good when multi-lane, however, I've not seen collisions like I'd expect. They also allow easier cross-traffic turns (ie, left turns in US, right in UK, etc) without a light-controlled turn. They are an easy solution when you have more than 2 streets involved. Further, they are very convenient if you need to do a U-turn.

I would question though, how well they work when emergency vehicles need to get through the traffic.
posted by Goofyy at 10:28 PM on May 3, 2006

I go through the Concord rotary (a traffic circle in eastern Massachusetts, USA) every day on the way to work. It sits on Route 2, a 4-lane major state road, and has three other two-lane roads feeding into it.

I hate the Concord rotary more than death itself.

Why? Because I typically enter it from Rt. 119. When there's substantial traffic on Route 2, they treat the rotary like a slight curve in the road. In particular, they don't slow down, as far as I can tell, and that makes it rather difficult for me to get into the rotary, because traffic entering the rotary must yield.

Fortunately for me (so far), I have an old car and poor impulse control, so I usually manage to get in fairly quickly. I hear these strange honking noises, though. Must be the Canadian geese endemic to the area. Sometimes I think I enjoy this a little too much (when I'm not being pissed off by it).
posted by Crabby Appleton at 10:48 PM on May 3, 2006

They seem to hate traffic circles, constantly fretting about their ability to get off of them at the right moment.

Look, kids! Big Ben! Parliament!
posted by evilcolonel at 11:30 PM on May 3, 2006

I appreciate the complaints people are making about the difficulty of getting onto a roundabout when a strong stream of through traffic makes it difficult. But for the traffic system as a whole I can see how this might be beneficial: the heavy traffic flow isn't interrupted, so the overall congestion is reduced.
posted by alasdair at 12:23 AM on May 4, 2006

What about an electronic speed limit sign that was hooked into the traffic lights and told you which speed to travel at in order to get a green light? That would work for some intersections wouldn't it? Wouldn't require a massive refit, either.

I'm not a big fan of roundabouts. In Australia the nearly-flat variety are referred to as overbouts - people simply drive over the top of them, according them even less courtesy than the common speedbump.

Then there is the ornamental variety, which has been spruced up with a shrubbery in the centre that blocks you from seeing the indicator lights of the other cars, so you have to watch them extra-carefully to assess their intentions. These are common in some Melbourne suburbs.

Lastly, there is the gargantuan variety, endemic to Canberra. If you find Parliament House using Google Earth, you'll notice the whole thing is built right in the middle of a massive roundabout about a kilometre in diameter.

Traffic in Canberra is pretty easy to deal with, if you have a decent sense of direction (which I don't). Some of this is probably because of the presence of big roundabouts, but it would be silly to say they are the sole factor. For a start, the place sprawls like a lazy cat. Even minor roads have wide, roomy curves that just go on and on. T-intersections are used much more than 4-way intersections, so right-of-way is generally obvious. Merge lanes are frequent on heavily-trafficked roads.
posted by Ritchie at 3:13 AM on May 4, 2006

posted by seanyboy at 4:16 AM on May 4, 2006

Roundabouts are less about traffic control than traffic safety. The primary goal is to prevent fatal accidents in certain intersections. For high volume intersections they really need much more real-estate than a traditional intersection to maintain volume.
posted by JJ86 at 8:17 AM on May 4, 2006

Crabby Appleton, you may also be familiar with the late Drum Hill Rotary, in Chelmsford. If you haven't been there in a while, be advised that the Rte.3 widening project has replaced it. Where there was a difficult traffic circle that generated lots of low-speed rear-end collisions, now there is a grid of four signal-controlled intersections. The genius of the design is that most of the time, you cannot be in the correct lane for where you want to go on the other side of the intersection. If you are in the lane that continues in the direction you wish to go, it fills up with cars going somewhere else before you get there. An amazing piece of work.
posted by Kirth Gerson at 9:29 AM on May 4, 2006

It isn't any big surprise that people are very good at naturally and efficiently navigating through an area congested with fellow people. Sit on a bench at the local shopping mall during Christmas season and you'll see that things run pretty smoothly.

The only difference is that at the mall if there is an 'accident' the worst that will happen is a couple people bump into each other and (maybe) say "I'm sorry." Any mistakes on the road and there's a decent chance that someone will be making a trip to the hospital. At the very least, the police will show up and clog up the road for a minimum of 45 minutes.
posted by wabashbdw at 12:05 PM on May 4, 2006

A few years ago in Jacksonville, FL they passed a large municipal bond authorization called The Better Jacksonville Plan, largely on the promise that much of the funds taxpayers would authorize would go towards the construction of a number of overpasses at key high traffic intersections. Unfortunately, since the proposal was passed in 1999, to now, many of the promised overpasses have been cancelled due to huge increases in the costs of building materials including concrete and steel for the bridge elements.

What's funny is that many of the overpasses that were built here in the early 1990's do very little to improve traffic flow, since they weren't built as cloverleaf designs. Instead, most of the major overpasses have stop lights for the surface road, and turn lanes to move left turn traffic on to the access ramps for the overpass road. Traffic on the surface road has to come to a full stop at timed intervals to allow left turn traffic to the overpassed road in both directions, and that backs up the off ramps for the overpassed road at peak hours. Net improvement per intersection at peak hours: very little, at great expense. Plus, we regularly get some amazing multi-car accidents on the ramps and in turn lanes when the monsoon rains come.

One wonders, as a layperson, what silliness is taught traffic engineers in civil engineering schools, that they are unafraid to display it publicly...
posted by paulsc at 9:25 PM on May 4, 2006

paulsc mentioned: What's funny is that many of the overpasses that were built here in the early 1990's do very little to improve traffic flow, since they weren't built as cloverleaf designs. Instead, most of the major overpasses have stop lights for the surface road, and turn lanes to move left turn traffic on to the access ramps for the overpass road. Traffic on the surface road has to come to a full stop at timed intervals to allow left turn traffic to the overpassed road in both directions, and that backs up the off ramps for the overpassed road at peak hours. Net improvement per intersection at peak hours: very little, at great expense.

The primary reason that this was probably done was for safety concerns. Engineers try to separate flows of traffic as much as possible especially when speeds are high. The same is done at rail crossings and high speed highway crossings.

Plus, we regularly get some amazing multi-car accidents on the ramps and in turn lanes when the monsoon rains come.

Engineers can't do much about driver stupidity. Every year when the first snows begin to fall here I see amazing accidents too. I have no problems with stupid drivers killing themselves but unfortunately they take a few innocents along with them.

One wonders, as a layperson, what silliness is taught traffic engineers in civil engineering schools, that they are unafraid to display it publicly...

Like I mentioned the main objective of roads is safety. This is of greater importance than speed or efficiency. We try to do as much as possible but there are many constraints with any roads. Right-of-ways are only so big, grade differences make many things impossible, utilities prevent major changes, politicians create unrealistic expectations, and generally the public is blissfully unaware of the complexities involved with roads. Roads and street right-of-ways are not just a place to drive a car. They perform many functions. Every public utility, from gas, sewer, water, telephone, electric, cable tv, etc uses the street. To make any major change affects them and creates huge expenses to modify.

Politicians who come up with grandiose plans without knowing all the potential impacts are the greatest danger. They happily piss away tax dollars on schemes which pose no real benefit and eventually create more problems down the way.
posted by JJ86 at 5:56 AM on May 5, 2006

Politicians who come up with grandiose plans without knowing all the potential impacts are the greatest danger.

And as support for that, this is about the former rotary I was talking about:

Chelmsford Selectman Philip M. Eliopoulos suggests injecting local influence in the planning process.

"Whatever the state comes up with for a plan, don't be afraid to look at it and modify it," Eliopoulos said. "We had more than a significant input. We basically redesigned the entire interchange."

Chelmsford Town Manager Bernard F. Lynch agreed.

Can't blame the engineers for that one.
posted by Kirth Gerson at 8:17 AM on May 5, 2006

I tip 20 percent.
posted by intermod at 7:30 PM on May 29, 2006