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Roundabout Way to Safer Driving

What's the best way to move traffic through an intersection? It may not be the way we're used to, with red and green lights denying or approving access. As the signal moves through its cycle there are many precious seconds when the intersection isn't doing its job: No vehicles are in it.

Route 15 detour map.jpg

Kenny Robinson of the Virginia Department of Transportation says there's a better way to move vehicles through certain junctions. He's working on such a project in Loudoun County: Constructing four roundabouts along Routes 50 and 15 in the Gilbert's Corner area.

In a couple of weeks, I'll feature this project on the Commuter page in the Sunday Washington Post Metro section. But for now, here's the basic idea: Unlike a traditional intersection, a roundabout is moving traffic all the time. If the setup is working well, traffic slows but doesn't form the long line of stopped vehicles that enhances opportunities for rear end collisions.

That's the promise of the traffic-calming project, but for now, there's likely to be a bit of pain for drivers who are just getting used to a new detour on Route 15, an important north-south link between Prince William and Loudoun counties.

Route 15 is closed between Route 50 and the newly built connector road called Howsers Branch Drive, about a quarter-mile south of Gilbert's Corner. Drivers are now using Howsers Branch Drive and a new roundabout on Route 50. That detour will be in place through May. This is likely to add five minutes to trips at off-peak times and up to 10 at rush hour.

As the project unfolds over the next few months, more detours are planned for Route 50 and Watson Road. The whole job is scheduled to be done late this year. For now, Robinson says, be patient and slow down while driving through that area. It's a new route and, as the project develops, a new style of merging for many motorists.

By Robert Thomson  |  April 9, 2009; 11:08 AM ET
Categories:  Driving  
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Roundabouts work well as long as everyone knows what to do and is polite. That makes think they'll never work here: people will stop (rather than slow down) before entering the roundabout, and the me-first attitude of drivers in the roundabout who won't let anyone in -- it's a vicious ... wait for it ... circle! The epitomy of this is Towson, MD's roundabout (York and Joppa Roads).

Meanwhile the roundabouts at the Arundel Mills exit off 295 work well, mainly because they a couple dedicated lanes that bypass the circle (e.g. Arundel Mills Blvd to 295N)

Posted by: zizzy | April 9, 2009 12:10 PM | Report abuse

Roundabouts funnel two lanes of traffic into one, like a lane closure on a highway. In theory, people can take turns smoothly and quickly. In practice, when does that ever happen?

Posted by: tomtildrum | April 9, 2009 12:54 PM | Report abuse

I'm afraid I agree with Zizzy -- the times I've seen roundabouts in place around here (Gaithersburg near the fairgrounds, that awful monstrosity at Blunt Rd and Watkins Mill Rd in Germantown/Montgomery Village), usually people's "me-first" attitude won't let them yield to people already in the roundabout (resulting in people already in the roundabout having to stop and congesting the circle), nor will they figure out that they really ought to NOT be in the "slow lane" if they're going to make a left (270 degree turn).

Another one of those things that works in theory, but not terribly well in practice in this area.

Posted by: | April 9, 2009 12:54 PM | Report abuse

From Dr. Gridlock: The main criticism I've heard of roundabouts is that they don't work well when traffic flows mainly in one direction. In this case, for example, if Route 50 was the dominant direction, the Route 15 drivers would be stuck.

That's why VDOT is creating the triangle pattern of roundabouts, with Howsers Branch Drive as a new connector between the main roads. So, at least in theory, there should be enough cars turning off within the roundabouts to use another road. That is what will create the gaps in traffic necessary for other cars to enter the roundabouts.

Still, I understand your point about driver behavior counting for a lot in making these things work. Drivers have to get the idea that the cars already in the roundabouts have the right of way.

Posted by: Robert Thomson | April 9, 2009 1:25 PM | Report abuse

The roundabout at Rhode Island Avenue and 34th Street (just across from NE DC) works well, but I think it was actually installed as a traffic-calming device to reduce the number of drivers going 55MPH on Rhode Island Avenue.

MD 216 in Howard County has similar roundabouts and they work well. They come where MD 216 crosses another major road (that is somewhat less traveled.)

And of course, I don't need to mention that the "traffic circles" in DC (that have traffic lights in them) are worse than useless, because not only do drivers need to keep an eye out for their exit, but they also need to be watching the confusing pattern of traffic lights that impedes their progress through the circle (which probably causes more accidents than it prevents).

Posted by: stuckman | April 9, 2009 1:49 PM | Report abuse

I love roundabouts from driving in the UK, in part because I love the concept of not requiring drivers to stop unless there's a reason to do so.

My concern with the use of roundabouts in the DC area is that people don't use their turn blinkers. VDOT compounds the problem by giving incorrect instructions on their website. The proper use of turn blinkers is critical in a roundabout because the turn blinker tells other drivers what you intend to do, which means they know whether they have to yield to you or whether you'll be exiting the roundabout before you cross their path (in which case they need not stop and yield).

I will continue in a second post about the proper protocol because the Post limits the length of comments.

Posted by: 1995hoo | April 9, 2009 3:10 PM | Report abuse

Continuing from before, the proper protocol at a roundabout in a country where traffic moves on the right (such as the United States) is as follows:

(1) If you are turning right (taking the first exit from the roundabout), approach in the right lane (if there are multiple lanes), signal right as you approach the roundabout, and continue to signal right as you pass through and leave the roundabout.

(2) If you are going straight (second exit), approach in either lane (again assuming there are two lanes), don't signal as you approach the roundabout, and then use your right signal after you have passed the first exit and before you reach the second exit. Continue your right signal as you leave the roundabout.

(3) If you are turning left (third exit, going 270 degrees around the roundabout) or making a U-turn, approach in the left lane, SIGNAL LEFT AS YOU APPROACH THE ROUNDABOUT, continue signaling left as you go around, then activate your right signal after you pass the exit before the one you want. Continue to signal right as you exit.

VDOT does not teach the proper use of the left signal on their website, and it's a serious omission. The use of the left signal tells entering drivers that you intend to remain on the roundabout and that they must yield to you. In the UK, the use of the right-turn signal in this situation is universally taught (remember they go the other way in roundabouts, so the signals are reversed) and most people follow the rule. It works FAR better than requiring people to guess at whether a driver is turning left. I imagine VDOT's response will be "they should signal a right turn just before exiting, and if they don't signal you should assume they're not exiting." But that runs counter to the concept of a roundabout, which works best when you don't have to assume anything.

Posted by: 1995hoo | April 9, 2009 3:16 PM | Report abuse

BTW, a thought on the comment from "stuckman": DC's "traffic circles" are not the same thing as roundabouts. DC's circles are horrible (especially Washington Circle), and indeed it was the poor design of many old-style "traffic circles" that soured many US jurisdictions on the use of circular road junctions. The biggest problem, though far from the only one, is that the old "circles" were generally designed to promote high-speed merging and weaving. Roundabouts do the opposite by forcing traffic to slow down and take turns. If drivers respect the yield rules, they work far better than "traffic circles."

Posted by: 1995hoo | April 9, 2009 3:20 PM | Report abuse

All I keep thinking is "what a stupid idea." I agree with other posters -- given DC drivers' behavior I think the roundabout will create more problems than it will solve.

Posted by: mensa58 | April 9, 2009 3:39 PM | Report abuse

1995hoo basically already said all of what I was going to say. Roundabouts work really well when people use them properly.

Problem with DC's circles is that pedestrians have to get across to the center of the circle, and they have to put signals in the circle to ensure that pedestrians can cross. Without them, do you think drivers would yield like they are supposed to? If drivers would behave the way they are supposed to, and not make excuses and play me-first, there wouldn't be as many traffic lights in this region.

And there are enough dumb drivers around here that I usually don't pay attention to other people's signals, since many times they don't signal when they turn, they signal a turn and then "change their mind", they signal a turn in the wrong direction, or leave the signal on for 2 miles errantly. I'd rather be safe than sorry, so I don't assume anyone is turning until I see their wheels begin to turn.

Posted by: thetan | April 9, 2009 4:11 PM | Report abuse

"...and the me-first attitude of drivers in the roundabout who won't let anyone in..."

Point of information...drivers in the circle aren't supposed to let people in, the people entering the circle have to yield and wait their turn when there are vehicles in the circle already. Then once you are in the circle, proceed to your destination without stopping.

Posted by: thetan | April 9, 2009 4:16 PM | Report abuse

My principal objections to roundabout is that people decide at the very last moment that they have to make a turn and then cut across one or more lanes of traffic to do that, rather than simply going around the circle one more time and then making their turn from the proper lane. You see this all the time in any traffic circle in this area. Drives me nuts!

Posted by: WashingtonDame | April 9, 2009 4:17 PM | Report abuse

"WashingtonDame," the scenario you cite shouldn't be an issue for the Gilbert's Corner project. US-50 and US-15 are both two-lane roads (meaning one lane in each direction, passing over the center line where allowed), so the roundabouts will most likely be a single lane as well.

VDOT has issued a policy statement saying that roundabouts in Virginia will never have more than two lanes, so I don't anticipate the same problem you see at Washington Circle or at the Hangar Lane Gyratory in London where people have to bomb across multiple lanes. Hopefully VDOT plans to use diagrammatic signage, too, which helps (you look at the sign and quickly count the number of exits if you're not familiar with the road); DC, as we all know, does not have this on its old-style traffic circles.

Posted by: 1995hoo | April 9, 2009 4:31 PM | Report abuse

I hope desighers of these Roundabouts are judicious in placement. Don't know the actual traffic volumes at Gilbert's, but this design would be very poor IF Rt 15 north were the highest volume. Their continued presence in the circle would completely block Rt 50 west traffic. I guess that the placement ON Rt 50 is due to 50 being the dominant flow. Some MD designs, tho, are poorly done. Gotta think!

Posted by: mapuser | April 9, 2009 10:17 PM | Report abuse

Good article, but one stylistic quibble. Dr. Gridlock says the "intersection isn't doing its job" if "no vehicles are in it." The goal of an intersection isn't to move vehicles. It's to move people.

If intersections have pedestrians crossing, it's doing its job even if no vehicles are in it. That might seem like a nitpicky point, but for 50 years we've had traffic engineering departments always optimize intersections to move the most vehicles, often at the expense of pedestrians and pedestrian safety.

Also, a bus carries as many people as a whole lane of traffic for several blocks. When traffic departments just think in terms of "vehicles", they often prioritize one single-passenger car as highly as a bus. If we let the buses "jump the queue" at a traffic light, for example, to avoid waiting for a minute or so, we actually move more people faster.

Posted by: David_Alpert | April 10, 2009 7:58 AM | Report abuse

The DOT people in the Wash Region are IDIOTS! I come from Jersey, land of traffic nightmares and roundabouts (we called them circles) for decades before DC ever had to worry about this stuff. Jersey took circles OUT about 10-15 years ago because they are a mess. Great in theory, terrible in practice. While I'm at it, we do left turns wrong here- the left turn arrow going on at the end- then you get a left turning veh stuck the whole cycle of the light blocking straight going vehs so only that left turning veh gets through at the very end when the left turn arrow comes on. And has anyone driven through the Cherry Hill Road and Route 29 intersection on Cherry Hill Road recently- that is supposed to be better than what was there??????? Here's an idea, how about a normal jug-handle. And don't give me this nonsense about the confines of the land, use eminent domain to take what you need- a jug handle doesn't require that much. The gov never seems to be afraid to use eminent domain to take someone's house to give the land over to a developer to build another useless strip mall.

Maybe the DOT people should try going to NJ/PA/NY area and seeing how they do it. There's a lot more traffic up there, and it's not perfect by any means, but they do a lot better job than down here.

Actually, I take back everything I just said. You guys are great, keep doing what you're doing. Put those circles in!! Keep building those screwed up intersections. You're great for business- I'm a PI lawyer.

Posted by: ryanrichieesq | April 10, 2009 8:56 AM | Report abuse

"I come from Jersey, land of traffic nightmares and roundabouts (we called them circles) for decades before DC ever had to worry about this stuff. Jersey took circles OUT about 10-15 years ago because they are a mess."

Those circles are not the same things as roundabouts. In traffic engineering the "modern roundabout" is distinguished from the older "traffic circle" in several ways. Try looking at the "four roundabouts" link Dr. Gridlock posted in the main post. Or you could even search Wikipedia for "roundabout" and "traffic circle"; while Wikipedia isn't really a reliable source for most things, their discussion of these sorts of road junctions are pretty good (perhaps because the people who like to vandalize their articles don't find traffic issues interesting?).

Posted by: 1995hoo | April 10, 2009 9:38 AM | Report abuse

Testing comments.

Posted by: Bob Greiner | April 13, 2009 12:27 PM | Report abuse

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