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#391
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In article , Wayne Pein wrote:
decreasing radius turns Such a turn could be designed explicitly for the purpose of slowing traffic. In that case, a sign can warn of it. If a curve is desired to slow traffic, then take the tightest radius value and use that for a constant radius turn. It will slow traffic just as good if not better and not have the drawbacks. |
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#392
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Mark Jones wrote:
"Frank Krygowski" wrote in message ... I'm not interested in excuses about how difficult decreasing radii can be.. This is bad design. For a PE to say what you just said is ridiculous. To resort to a decreasing radius means that the overall design is flawed. You should be able to go through a curve without needing to slow down the whole time. This is how you end up with trucks on their side with their cargo spilled all over the place. Are you saying you couldn't handle a decreasing radius curve? Do _you_, personally, need to have only _increasing_ radius curves to be able to successfully stay on the road? How about on a two lane road? Do you want to see only increasing curve radii when you're heading, say, east? And Mark - what sort of engineering tricks do you want used when you turn around and drive west? -- --------------------+ Frank Krygowski [To reply, remove rodent and vegetable dot com, replace with cc.ysu dot edu] |
#393
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"Alan Baker" wrote in message
... Again, you're lying. No need to ever hear from you again. PLONK |
#394
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Frank Krygowski wrote:
Mark Jones wrote: "Frank Krygowski" wrote in message ... I'm not interested in excuses about how difficult decreasing radii can be.. This is bad design. For a PE to say what you just said is ridiculous. To resort to a decreasing radius means that the overall design is flawed. You should be able to go through a curve without needing to slow down the whole time. This is how you end up with trucks on their side with their cargo spilled all over the place. Are you saying you couldn't handle a decreasing radius curve? Do _you_, personally, need to have only _increasing_ radius curves to be able to successfully stay on the road? How about on a two lane road? Do you want to see only increasing curve radii when you're heading, say, east? And Mark - what sort of engineering tricks do you want used when you turn around and drive west? Blind curves should *never* be decreasing radius. Never. If a road has traffic in two directions, a blind curve should be, by necessity, constant radius. This isn't that difficult a concept to grasp; I don't know why you're having such trouble with it. nate -- replace "fly" with "com" to reply. http://home.comcast.net/~njnagel |
#395
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"Nate Nagel" wrote in message
... So Frank is an engineer? I thought someone mentioned that he was a professor? I did a quick search on his name but all I came up with were a couple bicycling columns that seemed oddly reasonable, given his posts here. According to the what I could find out, he is a Professor with a Professional Engineer(P.E.) certification. I sure looks like he teaches in the Mechanical Engineering Technology program. Kind of interesting what he teaches, considering that I have a B.S. in Electronics Engineering Technology and built a large scale automated test system that would be related to his interests as listed on the following page. http://www.eng.ysu.edu/tech/MET.htm Scroll to the bottom of the page. |
#396
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"Wayne Pein" wrote in message
. com... I really find it hard to understand how he could justify a decreasing radius turn as being a reasonable thing to build. Just because a roading program can spit out the stakeout points for a particular piece of roadway, that doesn't mean that it is a good idea to build it. Such a turn could be designed explicitly for the purpose of slowing traffic. In that case, a sign can warn of it. The only one that I ever remember encountering did not have any warnings posted and the posted speed was O.K. for the entry, but not for the rest of the curve. I saw what was happening right away and got on the brakes or it would have gotten real interesting. I do not like decreasing radius curves as they can be very dangerous. |
#397
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Brent P wrote:
I would suggest Frank ride his bicycle through a decreasing radius turn that wasn't visable until he was in it such that it forced him to brake hard. This would probably be the best lesson as to why this sort of design should be avoided. Braking while turning is as ill-advised on a bicycle as it is driving. Probably more so. :-) Almost every time I make a turn on the bike, it's done with a decreasing radius, and with braking while in the turn! This is normal for a bicycle! Sheesh. Newbies! -- --------------------+ Frank Krygowski [To reply, remove rodent and vegetable dot com, replace with cc.ysu dot edu] |
#398
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Frank Krygowski wrote:
Mark Jones wrote: I really find it hard to understand how he could justify a decreasing radius turn as being a reasonable thing to build. Just because a roading program can spit out the stakeout points for a particular piece of roadway, that doesn't mean that it is a good idea to build it. I can tell you're finding it hard to understand! Look, let's think about this: Say you're laying out a two-lane road. Are you prepared to say every curve MUST be a constant radius - that is, a circular arc? Of course not. That's impractical, given difficulties with contours, rivers, right-of-way access, etc. Any curve where the next straightaway is not visible from the entrance to the curve, i.e. "blind" curve, yes. If there is ANY deviation from a perfectly circular arc, there MUST be either a decreasing radius or an increasing radius. And if the radius increases for drivers heading west, it MUST decrease for drivers heading east on the two-lane road. And when this occurs, it *must* be visible to a driver entering the curve. Obviously, this happens all the time. It's normal. And drivers handle it in a normal fashion. If a driver has an inability to negotiate such a curve, he's simply not competent. ASSuming that the curve is completely visible from its entrance, yes, this is a correct statement. If a driver can handle it on a two lane, but not on a freeway, it can only be because he has unrealistic expectations. I know of no design manual that forbids these things. If anyone _does_ know of such a manual, let's have a quote or two. I suspect that this is probably hidden in the AASHTO Green Book, but it is not on the web; if you want to read it you'll have to purchase a copy from them. nate -- replace "fly" with "com" to reply. http://home.comcast.net/~njnagel |
#399
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In article , Frank Krygowski wrote:
Mark Jones wrote: "Frank Krygowski" wrote in message ... I'm not interested in excuses about how difficult decreasing radii can be.. This is bad design. For a PE to say what you just said is ridiculous. To resort to a decreasing radius means that the overall design is flawed. You should be able to go through a curve without needing to slow down the whole time. This is how you end up with trucks on their side with their cargo spilled all over the place. Are you saying you couldn't handle a decreasing radius curve? Do _you_, personally, need to have only _increasing_ radius curves to be able to successfully stay on the road? Right for the insulting comments. Typical Frank. |
#400
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Mark Jones wrote:
I really find it hard to understand how he could justify a decreasing radius turn as being a reasonable thing to build. Just because a roading program can spit out the stakeout points for a particular piece of roadway, that doesn't mean that it is a good idea to build it. I can tell you're finding it hard to understand! Look, let's think about this: Say you're laying out a two-lane road. Are you prepared to say every curve MUST be a constant radius - that is, a circular arc? Of course not. That's impractical, given difficulties with contours, rivers, right-of-way access, etc. If there is ANY deviation from a perfectly circular arc, there MUST be either a decreasing radius or an increasing radius. And if the radius increases for drivers heading west, it MUST decrease for drivers heading east on the two-lane road. Obviously, this happens all the time. It's normal. And drivers handle it in a normal fashion. If a driver has an inability to negotiate such a curve, he's simply not competent. If a driver can handle it on a two lane, but not on a freeway, it can only be because he has unrealistic expectations. I know of no design manual that forbids these things. If anyone _does_ know of such a manual, let's have a quote or two. -- --------------------+ Frank Krygowski [To reply, remove rodent and vegetable dot com, replace with cc.ysu dot edu] |
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