I have blogged before about the impact of the roundabouts, and about a couple of other controversial traffic engineering projects here in Lincoln that weren’t exactly greeted with open arms. These projects, though accompanied by plenty can second-guessing and hand-wringing, have each had a significant impact on improving safety. They take their share of criticism, but the engineers are almost always right.
Yesterday, I went to the City Council’s public hearing on a proposal to redesign another intersection, this one at S. Coddington Ave. and W. Van Dorn Street. There have been 12 crashes at this location in the past two years. Eight of those were injury accidents, and a total of 22 (!) victims were sent to the hospital from those crashes. Every single crash was a right angle collision.
A roundabout will be only one of several options that will be examined for this intersection, and I have no idea if it would fit. A lot of that depends on how much land is available, I suppose. If a roundabout results, though, I can pretty much assure you that the number of crashes will plummet, the injury accidents will become exceedingly rare, and that the typical crash will be a minor one. I know this, because this is precisely what has happened at two other intersections that were converted to roundabouts at S. 33rd and S. 40th Streets and Sheridan Boulevard.
To illustrate the impact, I took this bar chart to the City Council showing the traffic crashes at S. 33rd St. and Sheridan Boulevard. The bar on the right depicts 104 total crashes in the eight years before the roundabout was installed. The bar on the left depicts the 21 crashes in the eight years after the roundabout was installed. The pink section of each bar represents the number of the total that were injury accidents: 27 before, two after. The scale is a quarter inch per crash. Hard to argue with those data.
39 comments:
If we could just get folks to signal their turn OUT of the roundabout it would help a bunch.
Folks don't like them because they are new - I was reading the book Traffic and it seems more folks actually get through a round about per minute than they do at a regular light - yet another plus for a roundabout
I'll admit I was skeptical at first when the roundabouts were installed at 33rd and 40th on Sheridan. I do believe the traffic moves well through both now most of the time. There are still a few "cows" that don't know what to do, but then they didn't know what to do with stop signs or lighted traffic signals either.
Do you have statistics on the number of cars that go through the circles annually compared to the intersections before they were converted? While I like the roundabouts and am happy to hear they have been successful, I also hear of folks that avoid them altogether and would be curious to see the same bar charts in terms of accidents/10,000 vehicles (or something along those lines).
Brian, I do not, but I'm sure that data will show that roundabouts usually increase traffic flow, rather than decrease. I go through the Sheridan roundabouts pretty much daily, and they work extremely well. I don't doubt there's some backup when school traffic peaks, but I certainly recall sitting through two or three cycles of the light at 40th before the roundabout. The Public Works Department probably has exact traffic counts on these intersections, pre and post, but anecdotally I can tell you that the volume has not dropped.
My only issue with these two is that they are a bit small. They would work even better had there been enough land to increase the circumference.
I see tons of problems with the proposed multi-lane design as wanted for 14th and Superior, and more then anything, it is Nebraskan's not adapting that I see the problems in.
I know people who now refuse to take Sheridan Blvd because of the round-about's you mentioned.
Change is good people!
Thanks for the lesson.
I was among those who think traffic circles are basicly silly and best suited for dumb Europeans. The results you point out are pretty convincing so my opinion is officially changed.
Most of the problems people see with roundabouts could be solved by drivers being more polite. Besides the previously mentioned use of turn signals, yielding before entering the roundabout is key. Otherwise, all legs do not empty evenly leading to traffic backing up. When the traffic in one leg clears, then the queue in another leg can go. The roundabout almost works like a signalized intersection by default. When a car yields before entering, this leaves a gap that gives a car in another leg the chance to enter. Chief, any chance to the DMV changing their licensing study guides and tests to teach more about roundabout use and etiquette?
From what I read, most of the objections seem due to this proposed roundabout being multi-lane, rather than single-lane.
"Change is good people!"
Change isn't good or bad, it just is.
--Don Draper
Roundabouts are the best. Those who are protesting this development are ones who don't even understand the concept or how to drive through one properly. Of course there'd be growing pains but once they figure it out, they'd think it is a godsend.
I agree with anonymous. Trafcon should put up signage in the roundabout for the first month that says, "SIGNAL YOUR TURN." This may help in educating drivers how to properly exit a roundabout (pg. 44, NE Drivers Manual).
9:01,
I'm not as sold on that turn signal in a roundabout as you. I do not like the idea of relying on the signal as the cue to "go." I want some kind of confirmation that the vehicle is really exiting before I pull into its path. I followed a guy this morning who was signaling a left turn from 10th and Van Dorn all the way to 10th and G, where I lost sight of him--over a mile. I suppose he turned left eventually, so maybe he was signalling an eventual left turn.
For me, the cue to "go," rather than a signal from a vehicle in the roundabout, is a gap that provides sufficient space for me to enter. This is why I wish the Sheridan Blvd. roundabouts were just a bit larger: I think they'd create larger gaps and make entering a little smoother. They work OK as is, but in my view they'd be even better with a few more feet.
California DOT has a great page about roundabout usage. I think if we were to start building larger ones in town, some similar resources would be very useful: http://www.dot.ca.gov/dist1/roundabouts/
Topeka, Kan., has installed several multilane roundabouts at intersections of busy streets (comparable to say, 27th and Old Cheney) and they are easy to negotiate and do speed the traffic along. If people in Topeka can figure these out, then I suspect Nebraskans can as well.
I did this spring witness a near rear-end hit at 40th and Sheridan cause by a nitwit DEAD-STOPPING in the roundabout to yield to someone waiting to enter; the person waiting, finally did enter because the dolt was waving her hand indicating the person should do so.
The guy who nearly hit the dolt was pretty irritated because, of course, had there been a crash, HE would have been ticketed, not the dolt who stopped. I hope the city does put the proposed roundabouts in.
There are other concerns about the 14th and Superior round-about proposal - besides the fact that drivers just do not understand them that well. The size issue is a big concern at this location in my opinion. It is somewhat land-locked with businesses at two of the corners.
There are also concerns about the pedestrian underpasses near a middle school and the addition of pedestrian signals on the other two sides of the intersection.
The design has pedestrians stopping in the median on Superior east of the intersection and 14th north of the entrance to Walgreens. Adding these signals will cause traffic back-ups as well.
Maybe they need a roundabout down at 14th & Warlick & Old Cheney. Either that, or an overpass/underpass interchange of some sort. As always, money is the main obstacle.
Chief-Left turns cause a lot of accidents by FTYROW. Roundabouts make everyone turn right only. Hence,in theory, fewer accidents.
256
I agree with the Chief that signals alone do not mean you can move in a roundabout, but I really do like it when drivers signal their intentions, and I like turn signals used in roundabouts like the one at 40th and something. Sheridan? However, in a bigger roundabout, as was said, that would be less important.
Chief,
I think the traffic circles are great for vehicles. However I wonder if they might be a bit more dangerous for pedestrians? There are school children using the sidewalks that will be trying to cross the traffic lanes. At Superior Street and 14th maybe a Pedestrian overpass is needed. If it is in the plans I think it would improve safety.
Gun Nut
but if i'm going straight do i signal in and out? because in order to navigate the roundabout I need two hands on the wheel, not one holding onto my blinker, btw what are the state statutes for navigating a roundabout? I saw nothing in the driver manual I found online I do agree that the sheridan ones are a bit too small
I love the idea of putting in a roundabout there. Traffic wouldn't have to wait through 2 or 3 signal cycles before you get through.
I do have a question on how would larger vehicles get through the intersection? I have seen the one on Sheridan and I don't know if a bus would clear that roundabout.
I have traveled many single lane "round-a-bouts" in Mass.and even in north Wichita, kansas.
The trouble is when you merge semi traffic and cars on the round a bout. Plse look and see the double set of tire marks on top of the brick @ 33rd & sheridan.
The semis' need more turning radius
In fact they cannot turn south on 27 @ van dorn without driving on my park ways.
I have traveled many of round a bouts in boston ,mass. even in wichita, kansas.
The trouble is merging semis with cars on the double lane the trucks needs a greater turning area.
See the double set of rear tiremarks on the 33rd a@ Sheridan Blvd.
Brian Fitzgerald:
I found Traffic counts on arterial street segments on the Public Works Department website. My anecdotal observations about the amount of traffic at 33rd and Sheridan and 40th and Sheridan appear to be correct.
Love the bar graph, chief.
These things are extremely expensive. Does the city have alot of spare money laying around to waste on this stupid idea. It's really just another effort to protect the smart drivers from the dumb idiots that can't deal with an intersection.
Mike 2:47.....unless things have changed, semis are not supposed to be using 27th St between Hwy 2 and South St. It is posted for no truck traffic. I know they use it anyway, but the road is not built for semis.
@ Mike April 5, 2011 2:47 PM:
There should be double-tire tracks on that brick. The brick there is called a "truck apron", it's engineered to allow trucks the extra turning radius they need. It's slightly raised, bumpy brick to discourage other vehicles from driving on it.
@ Anonymous April 5, 2011 9:50 AM:
I would hope any investigating officer of that type of collision would cite the lead vehicle for negligent driving or obstructing traffic.
@ Anonymous April 5, 2011 4:49 PM:
Actually, roundabouts are generally cheaper than traditional intersections (cheaper to install, cheaper to operate and maintain due to no traffic lights). They also improve traffic flow and therefore lower congestion. Average wait times at other intersections in Lincoln decreased significantly (~20 seconds) after roundabouts were installed.
There are several roundabouts in town that most people probably don't even know about. They are generally in neighborhoods and are smaller that the ones on Sheridan. The 3 lane roundabout is going to blow people's minds for a while.
I can only imagine if they put up signs telling drivers to signal their turns, some drivers are going to be using their left turn signals (think about it, you'll get it.)
From a different angle, is it only pure coincidence that the same engineering firm is designing all of the currently proposed roundabouts, and the city has just started pushing the roundabouts lately? Is there a contract with Ourston Roundabout Engineering?
I like the idea of having a roundabound at 14th and Superior.
http://www.youtube.com/watch?v=2ljFfL-mL70
I'm surprised that no one has yet written "This town has the worst drivers in the world", which is something often parroted by people living in every town in the world.
As the stats clearly show the number of accidents dramatically decreased at the intersection after the roundabout was installed. I'm curious however if anyone has looked at the accidents stats for any of the nearby intersections. For example the intersection of 33rd and High St. or 33 and Hillside St.
The reason I ask is because I live in the neighborhood south of Superior between I-180 and 14th Street. Many folks exit the neighborhood on 7th street every day. It's already a challenge during busy times to make a left turn onto Superior. Usually you have to wait for a break in traffic, one of which I assume is created by the lights at 14th and Superior. I'm wondering if the improved traffic flow at 14th and Superior may lead to more accidents at nearby intersections such as 7th and Superior and 10th and Superior because it may be even harder to take a left onto Superior street and folks will take more risks.
Chief,
Rather than provide a number of links about them, a quick google search "youtube roundabout" will yield a number of very informative videos. There is also one (add "lincoln" to the search) which is a graphic display of the 14th & superior intersection.
I would like to commend you for breaking with your traditional and predictable graphs or pie charts for a demonstration on the number of accidents. Much like seeing too much of a powerpoint, the change was refreshing.
If I were to caption this it would say..
"Can you match the suspect photo on the small photo to the line up on the long one"
A Barney Fife moment indeed.
"This is a Polaroid, and this is an extremely wide-screen Polaroid. It looks like the user didn't remove the lens cap for either picture."
multi lane roundabout. All I can think of is this:
http://www.youtube.com/watch?v=iAgX6qlJEMc
My only deal with the roundabouts on both 33rd and 40th are that they are really tight--they become difficult to use when the diameter is that small. If the one at 14th and Superior is appropriately sized (and that means larger than the other two, plus with room to grow for an area of town that is seeing growth) then I'd be for it. But I agree that that intersection is a bit of a mess.
I like roundabouts... and I am from Nebraska and don't see myself as a "cow". But on 14th and Superior? Really? How are the semis for Walgreen's, Ace Hardware, CVS and Family Dollar supposed to get through?
Have you sat on 14th from Flecher at 7:30 in the morning? What about all the school and daycare traffic? I understand something needs to be done... but roundabouts at a main intersection is not the answer. Have the light on 14th stay green longer. What about widening 14th? Has anyone looked at lengthening both right and left turn lanes? One last thing... does the public have a chance to vote on this?
I think there are still a lot of questions.
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