Road planning 2

[3dGrabber]

I was wondering how civil engineers plan roads embedded in rugged terrain (e.g. over a mountain). How do you find an optimal route (length, allowable gradient, minimal amount of earth moved,...) Is there any software for this or is it done 'by hand'?

 

[cvg]

a route study is usually done and depends on a lot of factors besides the ones you listed. Yes, software is used in road design, both planning stage and in final design also. Artistic renderings are often used for public meetings.

some of the other important factors are right of way, environmental impacts, drainage, cost, visual impact, aesthetics and constructability and traffic control and public acceptance.

 

[Debaser]

Design process (South Dakota style);

http://www.sddot.com/pe/roaddesign/docs/rdmanual/rdmch03.pdf

Factors affecting horizontal alignment choice;

http://www.sddot.com/pe/roaddesign/docs/rdmanual/rdmch05.pdf

Factors affecting vertical alignment choice;

http://www.sddot.com/pe/roaddesign/docs/rdmanual/rdmch06.pdf

The old hands will reminisce about doing calcs and drawings by hand, but right now I'm part of a team working on upgrading 20-odd kilometres of dual carriageway to motorway, in the UK, on fairly flat ground (certainly can't be described as rugged), and without computer modelling (MX, etc.) the design process would probably be so labour intensive as to be verging on uneconomic, given the number of parameters/standards we're trying to work with.

The only major alignment stuff I can imagine being done by hand thesedays is the very first simple 'line on a plan' layout, straight lines and simple curves and transitions to get a feel for the project.

 

[3dGrabber]

Thank you.
Do you use the software just to try out and adjust different layouts or does the software actively propose routes based on optimizations done using the input data (DEM, WOF,...)?
What products (Debaser mentioned MX[road?]) are available and widely used?

 

[Debaser]

The design is in the hands of the engineer.

In horizontal design for example there are ranges for the radii of curves that may be used for a certain design speed rather than one fixed value, which one is used in the end depends on many variables (available land, immovable obstructions, how the road flows, etc) which is where the skill of the engineer comes in. However, most design packages will allow for things like cut/fill balance calculations to be carried out as an alignment changes dynamically.

I read somewhere that the driver should be faced by 'a continuously unfolding ribbon of road', to get that feeling needs human input.

The design programs I'm familiar with are;

MX Road

http://www.bentley.com/en-US/Products/Bentley+MXROAD/

AutoCAD Civil 3d

http://images.autodesk.com/adsk/files/autocad_civil3d_brochure.pdf

CDS (previously PDS)

http://www.causeway.com/products/565.htm

 

[Apakrat]

When computers used trays of keyhole punch cards, locating access roads to proposed MCI microwave towers consisted of starting at top and locating road downward to desired existing access.



At 74th year working on IR-One2 - - UHK PhD - - -

 

[beej67]

If you're planning a long road through rough terrain, almost any engineer worth his salt is going to plot out a large topo map and get some trash paper and come up with a couple of conceptual alternates by hand before he shifts to doing it on the computer.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com