How to divide a road so that lanes are of equal width?

[athapa_WBC]

Hi all,

I'm doing some road marking layouts on an OS map and wondered if there was a feature within AutoCAD which will divide a length of road (which has varying width) transversely into several lanes of equal width, so that i can obtain some guidelines for the lanes.  Hope i am making sense!

Thanks

Jonny

[pendean]

AutoCAD CIVIL 3D? Or do you just have plain AutoCAD the can't tell the difference between a road or a duct or a pipe or a wall?
DIVIDE command, explained in HELP, if you are just drawing lines. Works very well.

[athapa_WBC]

We have plain AutoCAD 2014 and AutoCAD Map 3D.  Yes, i am drawing lines.  I am familiar with DIVIDE, however this will only give me the points in between.  I could do a rough job by using DIVIDE across different sections of the road and joining the points afterwards, which is a bit long winded and less accurate.  So i was wondering if there was a command to get AutoCAD to plot those equally spaced lines in between, by picking the two outer lines.

[pendean]

Of your connected lines/arcs where joined into a PLINE, you can OFFSET through points created with DIVIDE to get a better representation. Assuming your "road" widths don't change of course.

[athapa_WBC]

The road widths change a bit, but that should be good enough as a guide.  Thanks for your help.

[Kent1Cooper]

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@jkwa_WBC wrote:

... i was wondering if there was a command to get AutoCAD to plot those equally spaced lines in between, by picking the two outer lines.

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When you say "lines," do you mean only Line entities, or do you mean Polyline road edges?  If the former, would there always be the same number of them on each side of the road, and always contiguous at their ends?  If the latter, might they contain arc segments?  Would those on either side of the roadway always have the same number of segments, and if there are arc segments, would they always be the same number and in the same positions within the segment sequences of the two Polylines?

If under either entity type the answers are all yes, I can imagine a not-too complicated way to automate the process.  If changes in road width might occur within stretches of arc segments, then the resulting divider Polylines might not be truly tangent at all ends of arc segments, even if the road-edge Polylines are, but they should be close.

[athapa_WBC]

Hope the above screenshot will give a better idea.  They are polyline road edges containing some arcs.  I've been told the centre of the road doesnt necessarily need to be an equal width to the outer lanes so i think i can get away with offsetting.

[phubb]

Look for this lisp routine - it finds the centre line of two polylines which are a varying width apart.

http://www.jefferypsanders.com/autolisp_Rollin.html