Saturday, October 31, 2009

Streetscape 4: Roundabouts

I have a few observations about roundabouts.

I would be super bummed if the streetscape project went down the tubes because roundabouts became a linchpin issue.

Roundabouts seem to be very effective tools for some objectives and many circumstances. I think much of the friction in the streetscape debate stems from differences in objectives of the civic participants. There is also a little bit of extremism in the pro and anti roundabout rhetoric to heat things up.

Free Flowing
Roundabouts are not universally immune to congestion jams. The traffic engineer, which much of the community stands behind, told me straight up that Leucadia should not expect the roundabouts to handle more than 10,000ADTs. He implied that we will have to do something else after that.

I wrote here about why I was so surprised that some community leaders weren't interested in analyzing the traffic engineer's work. I still don't understand how it will take longer to cross Leucadia if we are keeping the HWY 101 open at freeway speeds than if we slow traffic and incorporate traffic calming/slowing infrastructure. The explicit goal behind the project is to slow traffic down and end the Leucadia drag strip. Let me be clear; I am not disputing the engineer's result. I am only saying counter-intuitive conclusions should be explained before widely accepted and used to support a decision.

Our city seems to base everything off Austin-Foust's traffic modeling. If we want to have trustworthy traffic reports that is the first thing that has to be improved and we should not selectively reject/accept the city's traffic analysis when it is beneficial to our objectives.

Given all that, it is surprising that the city's traffic engineer said the roundabouts would eventually fail. I did not ask, he volunteered this conclusion. I suspect that he is underestimating the capacity of the roundabouts. Most of the traffic is going to be flowing north/south and there will be little conflicting traffic for most of the intersections (unless there is lots of u-turning). Uneven delays at roundabouts seem to be most likely with heavy and uniform cross traffic and that doesn't describe HWY 101 very well.

The Green Question Mark
Another argument about roundabouts is they are greener. That can not be a universal reality.

We aren't comparing stop signs and roundabouts. The comparison is signals and roundabouts.

If there is no cross traffic then a sensor controlled signal will be "greener" because cars will not be forced to slow and then accelerate back up at the intersection. Steady speeds allow for fuel to be used more efficiently. In reality, there is going to be some conflicting cross traffic at any intersection. The question is, how much cross traffic do you need before the roundabout wins the "green" contest? Here is a photo of Ponto Avenue and HWY 101 in Carlsbad.
Thousands of cars go straight through this intersection without having to slow and stop. There is very little cross traffic and very little waiting for any autos. A roundabout here would result in ALL of the thousands of cars to slow and require a few to stop. My guess is that this intersection has a smaller CO2 footprint than if there was a roundabout. Maybe not, but there is some point where the trade off does not pay back in terms of greenhouse emissions. If the decision is to be based on such things then let's do the analysis. (The analysis should not be be based on optimizing all turning motions, as is now the case in the engineer's models).

Emergency Response
There are lots of public safety issues wrapped into the streetscape project. One that seems to be missing is emergency response times. One of the benefits of not living in rural zone is first responders can be at your doorstep in a few minutes. Fire, strokes, heart attacks, trauma and violent crimes can have very different outcomes as a consequence of delays in public safety response.

The city's fire department has said during public meetings that roundabouts can increase delays. I asked city staff about this and their response was the fire department has signed off on alternative 4a.

I am not saying that the delays should cause us to toss out roundabouts. We should make our decisions with our eyes wide open... if it matters.

One reason people like to live in low density rural zones is concrete and asphalt are not very comforting. Vegetation, vistas, open spaces and landscaping are more desirable to many.

See Also:
The Streetscape Workshop 4 Series
Results of Workshop 4


  1. Your pictures of Paris France don't reflect their other intersections that are just as congested. The entire city is congested not just the roundabouts. Look at the City of Truckee that will only install roundabouts. They are effective at keeping traffic moving and don't get congested like your pictures. During the winter their population probably equals LA.

    We should install more roundabouts and get rid of stop lights and stop signs.

  2. 15,000 people live in Truckee and the transportation issues are totally different than Paris or Leucadia.

  3. Your comments on the Hall property traffic study are not correct. One of the main enterences to the sports park is MacKinnon. The traffic study gave this two lane street with parking on one side a grade of "F". The planning commission and two council members agreed that this needed mitagation. The three boys did not seem to care.
    Their were other traffic issues that needed mitagation, too.
    The majority did not care to deal with any mitagation.

    I noticed your photos showing two blocked roundabout out of the country and one empty one. Your presentation seems to show a bias against round abouts.

  4. And while you were researshing for clogged round about photos in other countries, you omited the results of the recorded public preference from the workshop # 4 results.
    They are available. Why would you choose to not publish them? They seem pretty relevent to your topic.

  5. "I still don't understand how it will take longer to cross Leucadia if we are keeping the HWY 101 open at freeway speeds than if we slow traffic and incorporate traffic calming/slowing infrastructure."

    La Costa Ave, Leucadia Blvd, and Marchetta St. are currently lag points in getting through N. Coast Hwy 101. Collectively they can add several minutes to one's journey. Leucadia Blvd probably being the worst choke point - and the place where the least can be done (so far). I think it was Gary Murphy who said flashing stop lights at Leucadia Blvd work much better than the traffic light's incredibly slow cycles. I agree with that.
    Like roundabouts, flashing lights at an intersection make people slow down and interact with other drivers, pedestrians etc. AND they can make traffic get through that area more efficiently.

    We are not solely dependant on the Austin-Foust conclusions. But rely much on the history of the 5 other cities Peltz has improved traffic circulation and safety with roundabouts.

    There are four things SCARY about the first pictures JP posted.
    #1. Everyone is going clockwise.
    #2. There are more large trucks present than we get here all day on 101.
    #3. Still pictures suggest traffic is not moving at all, but hopelessly locked in that moment of time.

    But hell, it's Halloween!

  6. Kevin hates LeucadiaOctober 31, 2009 1:17 PM

    We get it Kevin, You hate roundabouts and you hate Leucadia, go jump in a lake.

    Roundabouts work, it's the simple truth. Sorry you can't understand that, but I don't think you understand much anyway.

    Go away.

    Between Kevin's closet hatred of Leucadia and the streetscape and JP's keep all surfing for locals only, this blog has gone to shit!!

    What a waste of time.

  7. I visualize large congestion concerns as two southbound lanes merge to one lane at each Rounabout. Mix in the bicycling masses and extra traffic on weekends and the functionality of the Roundabouts fail while causing increased tension for ALL commuters and ajoining neighborhoods as spillover occurs. How are they going to enforce the "No right turn during rush hour" at the roundabout? I'd do a 270 degree turnabout, totally screw up the roundabout, then head into the neighborhood to continue South on the backstreets! Also, will the largest of our firetrucks, when needed, be able to make the left turn into the 101 neighborhoods? Way too many ?'s unresolved.

  8. Kevin, 70% who are informed, want alternative 4a, with round abouts, accouding to the results of workshop 4. I do too.
    It will now go to the council. Your post would be relevent a month ago. What is your point in showing clogged, or seemingly stop action clogged, round abouts in Europe? Where are all the photos of the thousands of efficient ones? You say 'Leucadia leaders' don't care about the traffic study. Traffic going 25 or 30 mph and through round abouts have to be more eco-wise than 55 mph and stopping and starting at stop signs and lights. I do not believe that is true. Are your pen pals Andreen and Tucker behind all of this?

  9. "JP's keep all surfing for locals only'

    JP's stance is that our surf spots should be accessible to the public and not rented out to the highest bidder. Despite repeated attempts to drive this into your brain you still can't comprehend it.

  10. "How are they going to enforce the "No right turn during rush hour" at the roundabout? "

    Uh, exactly the same way they inforce it now? It'll still be a right turn when you get to within 30 degrees of your turn, no matter which direction you come from. Besides, a 270 turn would face you the into the wrong direction on a side street. It was morning traffic that cut through onto Leveta, and they were always going south. We haven't had the problem in a long time (and it's not due to the signs.)

    And as JP showed in his own video in a post a long time ago, you don't have to just do a 270 degree turn, but to screw traffic up at rush hour if that's your objective. You can make make a 720 turn or more.

    Yes, the fire trucks will be fine. As well as delivery trucks and everyone else who obeys the speed limits.

  11. Anon 1217,
    Blog post reflect our opinions. There is no claim for unbiased writing. The photos were fun so they were added. I don’t believe roundabouts are immune to congestion problems and I am skeptical that they will work as well as proposed in heavy traffic with heavy cross traffic, like El Camino and Encinitas Blvd. Fortunately that is not the case in Leucadia. There is little cross traffic. I tried support that idea in my post.

    Have they put a roundabout in somewhere in San Diego that has heavy crosstraffic? I will go visit it and bring back some video.

    Anon 1223,
    Write it up the results of the survey and send it to us. We’ll post it. If you want we will do so without your name on it.

    Anon 1217,
    Hall Property: Thanks for bringing that up. I’m clarifying the post. It was a side note and was meant to relate to the analysis of Santa Fe traffic. It is correct that the traffic projections on Santa Fe were not considered trustworthy, in part because of the multiple projects and Caltrans contingencies. It was not fair of me to not include the analysis of MacKinnon and the admission of failing grades in the final document. It was not intentional and I’m not happy about it.

    Anon 117,
    Please reread my post. I think wrote, “Roundabouts seem to be very effective tools…” It is true that I do not care as much as some whether or not we end up with roundabouts or not. I do not have a strong opinion about it. I do have a strong opinion about saying roundabouts are universal solutions to every intersection.


    It is important to remember that Peltz has not been asked to build a HWY 101 that optimizes traffic circulation. Leucadia wants something else. Peltz is the first one to remind us that there are always trade offs.

    The point about the five cities is unclear to me. Did they experience counterintuitive results in those cities? If they did I can lay this issues to rest.

    Everyone is upset about how fast cars are flying though Leucadia but are we overselling the product when we say that we will simultaneously have slower speeds and more traffic slowing devices AND this will result in shorter transit times across Leucadia? How does that happen?

  12. it's not easy being greenOctober 31, 2009 2:35 PM

    Say we need some traffic control at Grandview and 101. 2 options are stops signs or a roundabout.
    Grandview is fairly busy and vehicles attempting to turn north onto the 101 get backed up easily, idling their engines and burning fuel. A roundabout would slow down but not stop southbound 101 traffic and Grandview drivers could merge into the roundabout quickly, saving time and fuel. A stop sign would make every southbound vehicle stop which is unacceptable. A signal light is a 3rd option nobody wants.
    Advantage: Roundabout

  13. again
    The results of the fourth workshop are on the city of Encinitas web site. Go to government/city projects/north 101 streetscape/ workshop four results.

  14. I’m not seeking an outcome for the streetscape. I didn’t even turn in a streetscape survey. If anything, I’ve delayed posting some of my thoughts until after workshop 4. The streetscape is small potatoes compared to what our city, state, and country is facing.

    As for EcoWise calculations, my position is it not that simple. I’d like to think otherwise and would like to see the calculations. Roundabouts are not universally more “ecofriendly” than signals. Where is the cut off? I don’t know and my guess is the calculations have not been reviewed in the context of the Leucadia Streetscape. If you have them please forward that work to us. I’d love to post it and move on.

    The bottom photo shows a photo of an uncongested roundabout, in Leucadia.

  15. Not easy green,

    When I talked with the traffic engineer stop signs were not considered the alternative. Signal lights were. There is moderate cross traffic on grandview. I'd guess that the RA has the best chance of coming out as the green winner at that intersection.

    Verbal models aren't going to cut it. It is time to break out the math if we really care to find out... but if we already know what we want that's cool and which is greener doesn't matter.

  16. Dear JP's FriendOctober 31, 2009 4:57 PM

    The beach is not being sold to the highest bidder. It is being given to Dalager's friend without any bidding.

  17. So, you would suggest that after all this time,(17 yrs.), and effort and money and debate, and detailed workshops that we should challenge the traffic study and the examples of past successes of Pelz and Assoc.,the analysis and detailed comparison of 5 vs. 4a and a 70% approval of 4a from the community. I am done with the delays. This is a process that took 18 months of refinement to come up with, I think, is a masterful solution to acomplish the stated goals of the community and the project, which are the same. Those who have been involved have watched the process evolve, responding to community input.
    Why don't you go do a traffic study that will save us from blunder rather than speculate and plant seeds of doubt on a subject that, after "being invites by many people", chose not to follow, as you said.
    The throwing out negative speculation and seeds of doubt is what Andreen did during his efforts to stop the streetscape. You are better than that.

  18. Please! Truckee is a terrible example to use for justifying roundabouts. My sister and brother-in-law have a second house there, and I have driven through town many times, usually being the only car in the roundabout.

    It's mostly local traffic only. Interstate-80 carries most of the traffic. There is never any cut through traffic from a freeway clogged with commuters. Traffic only snarls when there is a blizzard, then everyone slow down everywhere.

    An example from South Lake Tahoe, ex-city manager Kerry Miller's old stomping ground, would have been better. There weren't any roundabouts last time I was there. Highway 50 is the main drag and there are skiers going to Heavenly Valley and gamblers to the Nevada side.

    Kevin's point is that roundabouts break down when traffic reaches a certain level. Then they either need stop signs or signal lights. I saw this chaos in Rio de Janeiro. Driving turns into a free-for-all, and traffic moves very slowly.

    Roundabouts work good in light traffic with minimal vehicles entering from side streets. It's better than a stop sign. I've seen this in Latin American. But the big city roundabouts are always signalized.

    Let's be careful what we wish for. That's all Kevin is trying to say.

  19. Roundabout lovers are myopic in they can't see the error of their ways. THEY DON'T WORK, especially on 101. Whatta thinking, two traffic lanes plus a bike lane merging into a small lane roundabout. Maybe you hippies need to smoke another joint. We know you all got medical marijuana cards.
    What about when the southbound traffic is heavy and they don't let the side street traffic in? Happens all the time at the three roundadorks we have now.
    By the way, what is alternative 6?

  20. willing to compromise?October 31, 2009 8:52 PM

    anon 605,

    It does not work like that. If the traffic study sucks it does not get better because it marinated on the shelf for 18 months before it was released.

    Even if Kevin is against 4a, the best alternative, it is clear he is for the streetscape and the process is not derailed in any way. Would you be willing to compromise with alternative 5? Are any alternative 4a supporters willing to compromise?

  21. Has anyone else noticed that Kevin posts crowded roundabout photos from Europe, I guess to subconsciously suggest that roundabouts lead to traffic congestion?
    I say put in the roundabouts – it will work, like they do on Leucadia Boulevard. How much “proof” is going to be enough?

  22. Kevin-

    You points are pretty good. Your overall message sounds anti roundabouts and I don't agree with the logic.

    The point about roundabouts not handling 10k cars per day is dead wrong. Look into any of the 1000 roundabouts that exist in CA and you will see that point is not true.

    I think you need to look at the alternatives. Roundabouts are much better than signals and all way stops. That's the honest truth.

    All you need to do is look at Leucadia Blvd. (13,000 to 15,000 a day). The backups happen at Vulcan/Hwy101, the signalized intersections at I5/Orpheus, and the all way stop(barely a back up compared to the signals) at Hygeia. The roundabouts at Hermes Ave. and Hymettus work splendid.

    Do some research into the ails and failures of signalized intersections. You will be amazed at how deadly and non performing they are. Just because they exist doesn't make them good. The same goes for extra wide roadways.

    Any how. It was a wonderful Halloween and I am so fortunate to live in Leucadia and be able to go trick or treating with my children in safe and fun neighborhoods.

    All be well tonight.


  23. I'm not anti roundabout. It would be fair to say that I do think the whole project is being over promised.

    Regardless of roundabouts... how does speeding and few controlled intersections get you through Leucadia slower than lower speed limits and traffic calming devices?

    In my original post I hoped to convey that I also thought the city's engineer was probably wrong about the 10,000ADTs. Besides, peak flow and the proportion of conflicting movements is more important.

    The question I have is how much can they handle?

    Not related to the HWY 101 situation: Are there any intersections in southern california that have/had heavy conflicting traffic where they put in roundabouts? All the ones I've seen in san diego have little cross traffic.

    I am more than willing to accept that RAs are typically better than signals at moving traffic, under most conditions. I spent some time about a year ago looking into the peer reviewed literature on this and did not see strong evidence that this was the case. Especially after this thread, I would love to see the data that shows this is the case. I will accept your help.

    The roundabouts on Leucaida blvd are evidence that RAs can work well. I've even been able to adjust my driving patterns to utilize them to get south of L. Blvd. That doesn't mean that they can not fail or that they are the universally superior alternative in ALL cases. The evidence should go beyond a couple mild case studies.

  24. "Regardless of roundabouts... how does speeding and few controlled intersections get you through Leucadia slower than lower speed limits and traffic calming devices?"

    I don't understand this comment. You only get to speed through a signal during those few seconds when its green. The remaining time, you have to stop, sit, and watch all the other drivers around you picking their nose.

    With roundabouts you typically don't need to stop, you can glide through them about 18 to 20mph.

    I think maybe you mean how does the interesection effect the overall traffic calming in the street. In that case, it only has immediate impacts for a block or so around the intersection. Other traffic calming is needed such as reducing lane widths, tightening other intersections, landscaping, and changing the geometrics of the road so its not a wide straight freeway.

  25. anon 817,

    You do understand! Kevin is saying the same thing as you.

    The traffic reports says that WITHOUT ANY NEW signals or roundabouts that it will take more time travel across Leucadia than if we put in roundabouts or signals.

    When you have all that time to pick your nose at the signal and slowing for the roundabouts and all the traffic calming how is it faster than blasting straight through Leucadia at freeway speeds? How are signals and roundabouts faster?

    Why would there be more diversion traffic off the 101 if it is faster with the roundabouts?

  26. "but are we overselling the product when we say that we will simultaneously have slower speeds and more traffic slowing devices AND this will result in shorter transit times across Leucadia? How does that happen?"

    The optimum amount of cars per day is not dependent on speed, but on flow. A 2 mile slow flow can accommodate more cars than that same distance with a faster flow plus 5 minutes of stopping. When you eliminate all 10 of our existing stops (as the Streetscape will do), flow increases to a degree that exceeds the cars per day at our current configurations in spite of a lower speed limit. And that's what roundabouts have done for traffic flow in the five other cities Peltz has designed. Unless they are lying to us and I find no reason they are.

    Seeing that our roundabouts will eliminate 90% of the stoping time we now experience at 10 stop locations, what can happen but more safety and more efficient traffic circulation? Fortunately, it's only 1 to 4 blocks west for the entire length of N. 101 and we're not in the middle of a 25 mile grid.

  27. When you eliminate all 10 stops? I know of two stops. One at Juanitas and one at Leucadia Boulevard. Where are the other eight stops?

  28. 3:21

    Unfortunately the stops will not be eliminated at Leucadia Blvd. But I was wrong, there will be 11 stops that will be removed not 10.
    They are:

    * Entering Leucadia from Carlsbad Blvd.
    * Entering Leucadia from La Costa Ave.
    * Exiting Leucadia to Carlsbad Blvd.
    * Exiting Leucadia to La Costa Ave.
    * Entering N. Coast Hwy 101 from Sea Bluff
    * Entering N. Coast Hwy 101 from Jupiter St.
    * Entering N. Coast Hwy 101 from
    Grandview St.
    * Entering N. Coast Hwy 101 from El Portal
    * Northbound 101 at Marchetta St.
    * Southbound 101 at Marchetta St.
    * Entering N. Coast Hwy 101 From Marchetta St.

  29. Fred,

    That increases the sensibility.

  30. Fred gets it. Hopefully others do as well. Thanks Fred!

  31. Nice photos of the Lorrie drivers blocking the roads in France durring their pay dispute a few years ago. I see they are even camped in the middle of the roundabout. I hope we don't have truck strikes here or Leucadia might be doomed.

  32. stop signs are horribleNovember 02, 2009 6:08 AM

    If Marchetta was signalized and set to rarely turn red for northbound and southbound traffic there would be better flow.

  33. I've scoured the internet and cannot find any pictures of signalized intersections that are backed up. He He!

    FYI, Roundabout at Cannon and Armada handles 40,000 cars a day. Mostly during the peak hours when the office parks, GIA load and un load their workers.

    It functions as a one lane roundabout, with two lanes approaching, no problems at twice the load that Hwy 101 will ever see.

    It has been in for ten years, and no accidents.

    The french pay strke photo is hilarious and whats more hilarious is our man "Kevin Questions" used it as a factual rebuttle as to why roundabouts are or can be a serious problem in his post.


  34. 6:08-

    "If Marchetta was signalized and set to rarely turn red for northbound and southbound traffic there would be better flow."

    Oh thats it. Encourage more I5 cut through traffic and speeding while penalizing the neighborhood to the west? No thanks. Bad idea.

    The Leucadia Blvd. is so screwed up and favors north/southbound traffic so much that the locals do not use it which encourages more neighborhood cut through traffic.

    Fred gets it. You don't. May I suggest you go talk to Fred and educate yourself to the issues affecting the area.

  35. "I hope we don't have truck strikes here or Leucadia might be doomed."

    As if truck strikers wouldn't dare clog a traffic intersection. But thanks for clearing up what that picture really was. Kevin, were you aware that that birds-eye view picture of a truck cluster was actually a trucker's strike when you posted it?

  36. That your roundabout images are from (I believe)London and France, when the junctions were deliberately blocked during transportation disputes, rather weakens your argument.
    I have lived in many many places with roundabouts and would take them any day c/w stop signs or lights.
    I believe your Ponto example was flawed too as i have been stopped many times northbound all along that section by a red light that was triggered by a car which had already turned right and gone !

  37. The post was not to make a point. It was to make people think and to post comments that strengthen their positions.

    The ratio of cars crossing Ponto Ave without stopping far exceeds those who have to stop. The argument that because you have experienced a red light at Ponto Ave that lights are worse is super weak.

    Everyone knows that in the USA roundabout can not back up and nobody ever has to stop upon entrance.


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