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So we're driving thru some intersections in a new subdivision near Vancouver ... not just ORDINARY 4-way-stop intersections, but ROUNDABOUT intersections ... and I comment to my wife that that's the most efficient way to design intersections these days.

So she says "How can this be more efficient than a 4-way-stop? That's why they call them ROUNDABOUTS ... because it's a ROUNDABOUT way to get to the other side of the intersection. It would be better to just stop, and then drive straight thru."

I proceeded to explain the "continuous motion theory" to her ... in intricate detail. Well ... not in quite as much detail as I had hoped ... I lost her on the next roundabout, and the debate turned back to road design. She really didn't get the "continuous motion theory", so I decided I'd be better off trying to explain why roads have ROUNDABOUTS in this day and age.

You see ... they've only been popping up recently around Vancouver. I think they were invented back in the late 1800s ... when cars became popular ... maybe they even used them in the horse-and-buggy days. I saw my first roundabout in London in the early 1970s ... and then I saw them again in Boston and Philadelphia a few years later. At the time, I thought they were just a curiousity ... something some Englishman dreamed up to keep the traffic flowing ... IN CIRCLES!

But I read a article about their recent local popularity ... and it does make sense. There's less accidents on roundabouts. Show me a 4-way-stop, and I'll show you an accident that's waiting to happen. Does everyone obey the stop signs? No! Does everybody wait their turn? No! As soon as you have 2 drivers disobeying the stop-signs ... at the same intersection ... at the same time ... there's a higher probability of an accident happening ... sooner or later. But I digress ... because I don't think that particular advantage of roundabouts has anything to do with PV.

So what does?

Well ... how about fuel economy? How about "continuous motion"? ...

To pass thru an intersection with a 4-way-stop, you must come to a complete halt. Your brakes might screech and heat up. This is hard on your break shoes ... energy leakage! ... and hard on your mileage. You're better off coasting to a stop.

Once the intersection is clear, you need to accelerate from your full stop. This takes energy ... LOTS of energy. Your car weighs a ton, so any time you're accelerating like that to move it from a complete stop to get back to your "cruising speed", you're going to guzzle more gas ... LOTS more gas ... and decrease your mileage. More energy leakage!

So what if you don't care about "going green" ... or the cost of fuel? What if you just want to get to your destination in the shortest possible time. Well ... roundabouts are great for that too ...

It sounds counter-intuitive that going in a semi-circle to pass thru an intersection is faster than if you could cut straight thru. But remember that if you cut straight thru, you must come to a full stop, then accelerate back to your cruising speed. This is grossly inefficient. It takes TIME ... and TIME is a valuable commodity.

It's better to MAINTAIN your speed (as much as you can ... given that you're rounding a curve and there might be traffic ahead of you) so that your one-ton car can KEEP ITS MOMENTUM THROUGHOUT THE INTERSECTION. You want a SMOOTH TRANSITION from one side of the intersection to the other.

I'm sure there's been studies on the optimal radius of a roundabout ... which will probably depend on a lot of factors ... including the size of the vehicles using it ... their fuel economy ... safety issues ... and so on. But one thing's for certain ... It needs to be ROUND! No sharp corners! Keep your car moving!

This isn't quite as true if you're the only car on the road, but if you're in heavy traffic, it's been proven time and time again that you can get more vehicles per hour thru an intersection "the roundabout way" than with a 4-way-stop ... or a signal light. It's the "CONTINUOUS MOTION" of the traffic circling the roundabout that makes it efficient.

I've created this thread to see if I can garner any support from my friends with like minds. So far, this debate is a 1-1 tie between my wife and I, so I need all the support I can get. Please vote ... my wife thinks I'm nuts. Maybe you have to be a pole vaulter to appreciate the beauty of this analogy?

Kirk

roundabouts>stop signs

I hate having to wait my turn.

As someone who has lived and driven in both Vancouver and New Jersey, Circles make allot more sense in terms of people driving on the west coast, perhaps not Los Angles drivers. But the mentality of Vancouver drivers are much more relaxed and allot less hostile than Jersey!

In term of demographics across the continent, the use of circles (or roundabouts if you would), makes more sense with much less aggressive drivers, the more aggressive drivers are and the more frequent use the "state bird", the more I tend to slam on my brakes on circles in Jersey than Vancouver. (Jim Stephenson Green party for MLA, west van)...

If we are trying to make connections to the vault, would the tuck and shoot be more of hitting a stop sign then going or would that be more like a rolling stop. (Depending on how much you tuck), OR training and competition approach from europeans vs americans (wink wink nod nod)

A great analogy.

Here's one way I see this analogy applied...

There are different schools of thought in coaching style. Some feel that an athlete should not advance to the next step of the process until they have mastered the previous step. So an athlete in this situation might not be allowed onto the pit until they can do an excellent pole run. And they might not be allowed to swing until they have the mechanics of the plant down perfectly. For a beginning high school athlete, they might not even get to compete in a meet their first season for fear of ingraining bad habits. I see these as stop signs. The athlete might progress in a very nice looking straight line... but multiply that by 100 athletes and you start seeing a lot of kids getting out of the car because they lose interest in trying to make it to point B.

The other extreme would be coaches who want their athlete to get from Point A to Point B, but they don't care how they get there. They can drive on sidewalks, speed, and otherwise break laws. The end result is a lot of these athletes crash and burn, literally. Sometimes they become uncoachable as well. Anyone who has ever run a camp sees kids like these. They are so far off the road, they don't want to get back on because it might mean moving backward before they move forward.

The roundabout way would be to allow athletes to progress, even if they have not perfectly mastered each element, but never letting them get too far off the path of the road. For example, I have had beginning vaulters who were not ready to carry the pole down the runway. Their plant mechanics were so terrible that it threw off the rest of the vault. Rather than make them spend every day doing pole runs, I let them slide the pole down the runway and continue to progress with the other stages of the vault. But we didn't forget about carrying the pole, they still practiced it and improved their plant. Those girls that were sliding the pole as freshmen were all carrying it as sophomores.


I think either school of thought is valid, as long as the roundabouts don't get the athletes too far off the road, and as long as you make sure to keep coming back to the things they need to work on to get back in the straight line. The stop sign method is a better method for some athletes, especially once you get to the college and post-collegiate level.


I have no idea if that was what Kirk had in mind with his analogy, but that was how I looked at it.