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Ways to Design Gas Savings into U.S. Roads
Submitted by jbr on Sat, 2008/08/09 - 2:06pm.
I could go along with removing some stoplights in the Knoxville area.
"roundabouts instead of intersections with traffic lights, lowering speed limits, and removing some stop signs. All of those could help drivers reduce gas consumption."
They certainly are. The new-ish traffic circle at Northshore and Concord has totally removed congestion at that intersection. Before the roundabout, southbound traffic on Concord Road would back up all the way to Turkey Creek Road, which is almost exactly one mile. Westbound traffic on Northshore would back up almost the same distance. Since the roundabout, traffic never backs up for more than two or three cars, even during rush hour.
Submitted by lovable liberal on Sun, 2008/08/10 - 9:38pm.
Up north, shitty land yacht beaters win most passenger car battles, though even shiny new big-ass pickup trucks give everyone smaller plenty of moments of terror.
Submitted by Hayduke on Tue, 2008/08/12 - 11:57am.
Worst case of this I ever saw was rush hour on the traffic circles in Milan (though the Italians all seemed to be good at it). You have to risk a fender just to get in. A rental car with the collision damage 'wager' trumps.
How about some queueing theory and coordinated timing for traffic light sequences. Seems like adjusting the cycles to optimize flow in the predominant direction during high-traffic times wouldn't be rocket science. Not only could it minimize idling, but knowing that speeding won't help you make the next light down the road could reduce jackrabbit commuting and the extra fuel usage for that.
I like roundabouts too. They're fun once you get used to the idea of flowing through them. And they make a convenient place to reverse your direction if you get off your intended path.
Submitted by djuggler on Sun, 2008/08/10 - 7:30pm.
An Oak Ridge company is testing cameras on traffic lights to control traffic flow more smartly. The purpose of the cameras is to replace the magnetic strips in the road that detect cars at the lights.
Submitted by lovable liberal on Sat, 2008/08/09 - 7:22pm.
Up here in Massachusetts, we call roundabouts rotaries. (Milkshakes are frappes, too, oh never mind.) We call them rotaries when we're not in them or trying to get through them or trying to get a tow truck to get our wrecked cars out of them, in which cases our language is quite a bit more colorful.
Rotaries only work with a very polite and unhurried driver population or a small traffic flow. You'll learn to hate them, too.
Submitted by Anonymous (not verified) on Sat, 2008/08/09 - 8:16pm.
There are three distinct different things: Rotaries, Roundabouts and Traffic Circles. The easiest of these to explain are traffic circles. They're aestheticly pleasing means of joining roadways where a standard stop sign would typically be used. Now due to their small radius, they still for all intensive purposes operate as a stop sign controlled intersection, but often times with a landscaped area broken up in the middle.
Now roundabouts are designed with the idea of keeping traffic moving around the circle, but at lower speeds, to prevent idling. They have a typical travel lane with a driveable apron to the inside that allows for 18 wheelers to traverse them. In a roundabout you're supposed to travel somewhere in the magnitude of 18-20 mph around them. They're very efficient to a point, but once you get to a highly congested state they break down. Also they take a lot of land. FHWA's minimum width is around 100' from pavement edge to pavement edge. This means when you add in curbing and sidewalks it's close to a minimum of 120'. In areas where the land is available and traffic projections don't go into a highly congested state, they're more effective. But as a retrofit they're difficult to use due to the large amounts of land area needed.
Rotaries are an even large version of a roundabout, that is designed for much higher speeds. These are typically used in high congestion areas but require a lot of land and a lot of planning.
Now all these are often confused with each other by the general public, but are starting to receive more thought in implementation.
At Five Points in East Maryville we got a traffic circle put in. The first day I saw some redneck literally drive through the middle of the circle to the other side. I almost wrecked while laughing so hard.
At Five Points in East Maryville we got a traffic circle put in.
easiest of these to explain are traffic circles. They're aestheticly pleasing means of joining roadways where a standard stop sign would typically be used.
I definitely would not call the traffic circle in Maryville aesthetically pleasing.
Safer traffic is with less, not more. Hans Monderman is a traffic engineer who believes signs to be a danger to driving. He encourages designing the roads for safety with traffic circles, putting pedestrians closer to the traffic, leaving curves in the road rather than straight roads, narrowing roads, removing signs, etc.
Submitted by bizgrrl on Sun, 2008/08/10 - 10:04am.
Regarding the changes made to the Knoxville road,
the road has some lines painted across it, and some ruts have been carved into the road to audibly warn you to slowdown. These are fairly intangible but work! You cannot help but slow down.
After having looked into slowing people down in our neighborhood and working with the City of Alcoa, I never came across the "rut" solution. Most of the reports (trafficcalming.org) have the humps, tables, traffic circles, narrowing, and more, but no ruts.
Have you seen any statistics or measurements on the effectiveness of ruts?
Submitted by djuggler on Sun, 2008/08/10 - 1:23pm.
Not beyond personal experience. "ruts" was my own word choice but these are not uncommon in road designs. When I-40 ended in Memphis to become regular roads, ruts were used to help alert drivers of the major change. Grooves and bumps are used to help awaken drivers on the Interstate.
If you put a series of grooves or bumps in the road and drive over them too fast it feels and sounds like you are ripping the rubber from your tires.
Submitted by lovable liberal on Mon, 2008/08/11 - 3:03pm.
Well, we haven't been spending on infrastructure, that's for sure. Although, the vehicle detectors that are increasingly common do help a lot. In 1973, you might have to wait for 2 minutes at a light when no one else wanted to pass through the intersection.
Submitted by Factchecker on Mon, 2008/08/11 - 9:47pm.
In 1973, you might have to wait for 2 minutes at a light when no one else wanted to pass through the intersection.
True, but we have to do that all over the place now. How about Alcoa Hwy and Cumberland (from either to the other)? I'd like to have some of that gas back, not to mention time. But yes, it must have been crudely done back then (--I wonder how).
It seems they did get out of sync every so often, but could be re-synced and were, until about the time Jimmy Carter was ran out on a rail for being too judgmental.
Submitted by Up Goose Creek on Mon, 2008/08/11 - 10:14pm.
I hope you'll explain what Jimmy Carter had to do with the Turnpike in OR. I recall them being synced way back in the Johnson administration, left town during Nixon and haven't paid much attention since.
Henley St lights are synced pretty well until you hit Western. I've hit almost all green coming into town on Kingston Pike on several occasions (Bush administration).
____________________________________
"Whoever corrects a mocker invites insult; whoever rebukes a wicked man incurs abuse."
Submitted by Brian A. on Mon, 2008/08/11 - 11:49pm.
Do roundabouts require more space than stop-light intersections? It seems that could be a problem if you want to make a conversion with existing roads.
With a traffic light, TDOT would install turn lanes in all four directions. The problem with the light is that TDOT would have to cut a nearby hill down four to six feet to get the needed sight distance a traffic light requires. That would require taking part of the Shell Station entrance and the driveways of two or three houses, which would mean the houses would have to be acquired because they are so close to the road, the mayor explained.
With a roundabout, similar to the one at Five Point on West Broadway in Maryville, the intersection could be moved sufficiently so no families would be displaced.
The roundabout would be moved slightly toward Louisville (across Mentor Road from the Shell Station) into the large vacant field owned by Fort Sanders Regional Medical Center and across Louisville Road from the gas station on some property owned by the Scott McClellans, Anderson said.
+1 for roundabouts. They sure seem more efficient.
They certainly are. The new-ish traffic circle at Northshore and Concord has totally removed congestion at that intersection. Before the roundabout, southbound traffic on Concord Road would back up all the way to Turkey Creek Road, which is almost exactly one mile. Westbound traffic on Northshore would back up almost the same distance. Since the roundabout, traffic never backs up for more than two or three cars, even during rush hour.
The difference is amazing.
~Russ
Do you remember how many people were so up in arms about that round-a-bout? I think they're great!
Doug McCaughan
Link...
The new-ish traffic circle at Northshore and Concord has totally removed congestion at that intersection.
Quite a few wrecks still happen as various drivers debate with their cars the meaning of the word "Yield".
The nice folks in Montgomery Cove think Yield means the other guy stops.
It would have been better is the radius was larger. But like so many ideas like this, the design was the problem.
The nice folks in Montgomery Cove think Yield means the other guy stops.
Must be libertarians.
Must be libertarians.
I think it is more like Tahoe trumps Corolla.
Up north, shitty land yacht beaters win most passenger car battles, though even shiny new big-ass pickup trucks give everyone smaller plenty of moments of terror.
Liberty and justice for all.
My home
And the good libertarian rule of thumb would be "he who loves his car least, goes first."
Worst case of this I ever saw was rush hour on the traffic circles in Milan (though the Italians all seemed to be good at it). You have to risk a fender just to get in. A rental car with the collision damage 'wager' trumps.
How about some queueing theory and coordinated timing for traffic light sequences. Seems like adjusting the cycles to optimize flow in the predominant direction during high-traffic times wouldn't be rocket science. Not only could it minimize idling, but knowing that speeding won't help you make the next light down the road could reduce jackrabbit commuting and the extra fuel usage for that.
I like roundabouts too. They're fun once you get used to the idea of flowing through them. And they make a convenient place to reverse your direction if you get off your intended path.
An Oak Ridge company is testing cameras on traffic lights to control traffic flow more smartly. The purpose of the cameras is to replace the magnetic strips in the road that detect cars at the lights.
Doug McCaughan
Link...
Up here in Massachusetts, we call roundabouts rotaries. (Milkshakes are frappes, too, oh never mind.) We call them rotaries when we're not in them or trying to get through them or trying to get a tow truck to get our wrecked cars out of them, in which cases our language is quite a bit more colorful.
Rotaries only work with a very polite and unhurried driver population or a small traffic flow. You'll learn to hate them, too.
Liberty and justice for all.
My home
There are three distinct different things: Rotaries, Roundabouts and Traffic Circles. The easiest of these to explain are traffic circles. They're aestheticly pleasing means of joining roadways where a standard stop sign would typically be used. Now due to their small radius, they still for all intensive purposes operate as a stop sign controlled intersection, but often times with a landscaped area broken up in the middle.
Now roundabouts are designed with the idea of keeping traffic moving around the circle, but at lower speeds, to prevent idling. They have a typical travel lane with a driveable apron to the inside that allows for 18 wheelers to traverse them. In a roundabout you're supposed to travel somewhere in the magnitude of 18-20 mph around them. They're very efficient to a point, but once you get to a highly congested state they break down. Also they take a lot of land. FHWA's minimum width is around 100' from pavement edge to pavement edge. This means when you add in curbing and sidewalks it's close to a minimum of 120'. In areas where the land is available and traffic projections don't go into a highly congested state, they're more effective. But as a retrofit they're difficult to use due to the large amounts of land area needed.
Rotaries are an even large version of a roundabout, that is designed for much higher speeds. These are typically used in high congestion areas but require a lot of land and a lot of planning.
Now all these are often confused with each other by the general public, but are starting to receive more thought in implementation.
Nope. Rotaries here in New England are the same as what you call roundabouts.
Liberty and justice for all.
My home
At Five Points in East Maryville we got a traffic circle put in. The first day I saw some redneck literally drive through the middle of the circle to the other side. I almost wrecked while laughing so hard.
At Five Points in East Maryville we got a traffic circle put in.
easiest of these to explain are traffic circles. They're aestheticly pleasing means of joining roadways where a standard stop sign would typically be used.
I definitely would not call the traffic circle in Maryville aesthetically pleasing.
No signals works in Hanoi
Hanoi crazy night traffic from v!Nc3sl4s on Vimeo.
Safer traffic is with less, not more. Hans Monderman is a traffic engineer who believes signs to be a danger to driving. He encourages designing the roads for safety with traffic circles, putting pedestrians closer to the traffic, leaving curves in the road rather than straight roads, narrowing roads, removing signs, etc.
Knoxville as begun using similar techniques to re-engineer roads for traffic control.
Doug McCaughan
Link...
Regarding the changes made to the Knoxville road,
After having looked into slowing people down in our neighborhood and working with the City of Alcoa, I never came across the "rut" solution. Most of the reports (trafficcalming.org) have the humps, tables, traffic circles, narrowing, and more, but no ruts.
Have you seen any statistics or measurements on the effectiveness of ruts?
Not beyond personal experience. "ruts" was my own word choice but these are not uncommon in road designs. When I-40 ended in Memphis to become regular roads, ruts were used to help alert drivers of the major change. Grooves and bumps are used to help awaken drivers on the Interstate.
If you put a series of grooves or bumps in the road and drive over them too fast it feels and sounds like you are ripping the rubber from your tires.
Japan has melody roads which play songs as you drive over them due to the spacing of the grooves and bumps.
Doug McCaughan
Link...
As I've ranted before, the Oak Ridge turnpike had timed stop lights circa 1973. They even worked.
Well, we haven't been spending on infrastructure, that's for sure. Although, the vehicle detectors that are increasingly common do help a lot. In 1973, you might have to wait for 2 minutes at a light when no one else wanted to pass through the intersection.
Liberty and justice for all.
My home
In case you may not have listened to the NPR audio interview referenced in original post, a couple things mentioned....
~50% fewer collisions at roundabouts than traffic signals
80% - 90% fewer deaths and injuries at roundabouts than traffic signals
"Look kids, Big Ben,Parliment!"
True, but we have to do that all over the place now. How about Alcoa Hwy and Cumberland (from either to the other)? I'd like to have some of that gas back, not to mention time. But yes, it must have been crudely done back then (--I wonder how).
It seems they did get out of sync every so often, but could be re-synced and were, until about the time Jimmy Carter was ran out on a rail for being too judgmental.
I hope you'll explain what Jimmy Carter had to do with the Turnpike in OR. I recall them being synced way back in the Johnson administration, left town during Nixon and haven't paid much attention since.
Henley St lights are synced pretty well until you hit Western. I've hit almost all green coming into town on Kingston Pike on several occasions (Bush administration).
____________________________________
"Whoever corrects a mocker invites insult; whoever rebukes a wicked man incurs abuse."
That was meant to be a joke, I guess not obviously so. I just don't know why or when they quit. It would be interesting to find out.
I've never noticed any synced segments in this town. It can't be that hard.
Do roundabouts require more space than stop-light intersections? It seems that could be a problem if you want to make a conversion with existing roads.
Brian A.
I'd rather be cycling.
Interesting question. This came up recently in Blount County. The answer, at least in this case, is surprising:
Public hearing set on congested intersection in Louisville
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