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DannyCounts
Posts: 31
Registered: ‎10-08-2003
Message 1 of 5 (61 Views)

Varying crossgrade of Exist. Road that needs to extend

61 Views, 4 Replies
12-06-2004 05:12 PM
think about the crossgrade between the centerline profile of an existing road and a profile running through the top surface of the same road at any given offset, say 12'. Again think about the cross-grade between those two profiles. If it is an existing roadway, chances are the cross-grade varies. Is there a way to project the varying crossgrade between those profiles further out to any given offset? I can build a surface of the 3D polys representing these two profiles, I also tried extending the TIN lines, but then they begin to cross and I don't know if that is representative of what it should be doing. Is there any other way to accomplish this?
*Joe Bouza
Message 2 of 5 (61 Views)

Re: Varying crossgrade of Exist. Road that needs to extend

12-07-2004 12:57 PM in reply to: DannyCounts
Hi Danny, I think the best you can do for this type of condition is to locate transition points and draw 3dpoly lines to approximate the existing cross slope. Then you can extend thes 3dpoly lines to "extend" the existing condition. But, I you are widening the road why not use a constant, or more mathematical cross slope ? Joe "DannyCounts" wrote in message news:3073171.1102382002736.JavaMail.jive@jiveforum2.autodesk.com... > think about the crossgrade between the centerline profile of an existing > road and a profile running through the top surface of the same road at any > given offset, say 12'. Again think about the cross-grade between those two > profiles. If it is an existing roadway, chances are the cross-grade > varies. Is there a way to project the varying crossgrade between those > profiles further out to any given offset? I can build a surface of the 3D > polys representing these two profiles, I also tried extending the TIN > lines, but then they begin to cross and I don't know if that is > representative of what it should be doing. Is there any other way to > accomplish this?
*Don Reichle
Message 3 of 5 (61 Views)

Re: Varying crossgrade of Exist. Road that needs to extend

12-07-2004 06:13 PM in reply to: DannyCounts
Hey Danny; I would echo Joe, but also ask if the outcome is to keep the existing conditions (which bring to mind a "wash-board" effect on the passengers in the vehicles traversing this road) or to improve the condition? If the former, you can painstakingly emulate this condition with separate profiles attached to the transition alignments for your widening. I use the term painstakingly, because you will spend a great deal of time with Excel or QuattroPro attempting to report the varying cross-grades at each 25 foot station of the controlling alignment. And God forbid if you need to account for intersections through this corridor! If the latter, then I would find whichever of the two edge conditions (read rights of way) create the condition which will enable you to adopt a normal crown section for your locality, providing a smooth ride for the vehicle occupants. This edge condition would be the one which provides the closest daylight line to the right of way in question. That way you keep the impact of retrofit grading to a bare minimum. And at least you can account for your intersections more reasonably because you will have only one cross-grade to deal with through each one. HTH -- Don Reichle "King Of Work-Arounds" Barghausen Consulting Engineers Kent, WA USA LDT3 - SP1/CD3 - SP1 On WIN2K SP4 Dell 1.6 Ghz P4 512MB RAM NVIDIA 32MB AGP "Joe Bouza" wrote in message news:41b61930$1_3@newsprd01... > Hi Danny, > > I think the best you can do for this type of condition is to locate > transition points and draw 3dpoly lines to approximate the existing cross > slope. Then you can extend thes 3dpoly lines to "extend" the existing > condition. But, I you are widening the road why not use a constant, or more > mathematical cross slope ? > > > Joe > > > "DannyCounts" wrote in message > news:3073171.1102382002736.JavaMail.jive@jiveforum2.autodesk.com... > > think about the crossgrade between the centerline profile of an existing > > road and a profile running through the top surface of the same road at any > > given offset, say 12'. Again think about the cross-grade between those two > > profiles. If it is an existing roadway, chances are the cross-grade > > varies. Is there a way to project the varying crossgrade between those > > profiles further out to any given offset? I can build a surface of the 3D > > polys representing these two profiles, I also tried extending the TIN > > lines, but then they begin to cross and I don't know if that is > > representative of what it should be doing. Is there any other way to > > accomplish this? > >
*Laurie Comerford
Message 4 of 5 (61 Views)

Re: Varying crossgrade of Exist. Road that needs to extend

12-07-2004 09:16 PM in reply to: DannyCounts
Hi Don, I agree with you and Joe on the design methodology, but a significant number of of our clients use the extend existing cross fall method of design. Let me go into advertising mode for ARD again where you can do it easily do it either way. -- Regards, Laurie Comerford www.cadapps.com.au "Don Reichle" wrote in message news:41b66370$1_3@newsprd01... > Hey Danny; > > I would echo Joe, but also ask if the outcome is to keep the existing > conditions (which bring to mind a "wash-board" effect on the passengers in > the vehicles traversing this road) or to improve the condition? > > If the former, you can painstakingly emulate this condition with separate > profiles attached to the transition alignments for your widening. I use > the > term painstakingly, because you will spend a great deal of time with Excel > or QuattroPro attempting to report the varying cross-grades at each 25 > foot > station of the controlling alignment. And God forbid if you need to > account > for intersections through this corridor! > > If the latter, then I would find whichever of the two edge conditions > (read > rights of way) create the condition which will enable you to adopt a > normal > crown section for your locality, providing a smooth ride for the vehicle > occupants. This edge condition would be the one which provides the closest > daylight line to the right of way in question. That way you keep the > impact > of retrofit grading to a bare minimum. And at least you can account for > your > intersections more reasonably because you will have only one cross-grade > to > deal with through each one. > > HTH > > -- > Don Reichle > "King Of Work-Arounds" > Barghausen Consulting Engineers > Kent, WA USA > LDT3 - SP1/CD3 - SP1 > On WIN2K SP4 > Dell 1.6 Ghz P4 > 512MB RAM > NVIDIA 32MB AGP > > > "Joe Bouza" wrote in message > news:41b61930$1_3@newsprd01... >> Hi Danny, >> >> I think the best you can do for this type of condition is to locate >> transition points and draw 3dpoly lines to approximate the existing cross >> slope. Then you can extend thes 3dpoly lines to "extend" the existing >> condition. But, I you are widening the road why not use a constant, or > more >> mathematical cross slope ? >> >> >> Joe >> >> >> "DannyCounts" wrote in message >> news:3073171.1102382002736.JavaMail.jive@jiveforum2.autodesk.com... >> > think about the crossgrade between the centerline profile of an >> > existing >> > road and a profile running through the top surface of the same road at > any >> > given offset, say 12'. Again think about the cross-grade between those > two >> > profiles. If it is an existing roadway, chances are the cross-grade >> > varies. Is there a way to project the varying crossgrade between those >> > profiles further out to any given offset? I can build a surface of the > 3D >> > polys representing these two profiles, I also tried extending the TIN >> > lines, but then they begin to cross and I don't know if that is >> > representative of what it should be doing. Is there any other way to >> > accomplish this? >> >> > >
*Karl Fuls
Message 5 of 5 (61 Views)

Re: Varying crossgrade of Exist. Road that needs to extend

12-08-2004 03:16 AM in reply to: DannyCounts
Try this.... Sample for cross sections using the surface you have for the existing road - make sure you put a boundary on the surface that will stop it at the edge of road or slightly inside. When doing this, import the sample lines. Trim the resultant 2d sample lines to centerline on one end and edge of road on the other. Project these 2d lines to the road surface. This will create 3d lines at the sampled stations that will reflect the cross slope at each section. Note that the resultant lines will have vertices wherever they cross the surface tin lines. Extend these 3d lines to the desired offset that will accommodate your widening (or wider - it won't hurt). Build a surface from the 3d lines (I'd use them as breaklines). Now you can sample your transition alignment to this surface and the profile will be an extension of existing cross slope at each sampled station. I would probably smooth the curbline to some reasonable profile so future overlays look better. -- Karl Fuls PLS Autocad AEC Training and Consulting Autodesk Discussion Group Facilitator DannyCounts wrote: > think about the crossgrade between the centerline profile of an existing road and a profile running through the top surface of the same road at any given offset, say 12'. Again think about the cross-grade between those two profiles. If it is an existing roadway, chances are the cross-grade varies. Is there a way to project the varying crossgrade between those profiles further out to any given offset? I can build a surface of the 3D polys representing these two profiles, I also tried extending the TIN lines, but then they begin to cross and I don't know if that is representative of what it should be doing. Is there any other way to accomplish this?
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