AutoCAD Civil 3D

[#1]

Hello,

This is my first post here, so hi.

We have just switched (or rather supplemented) MX with C3D. And I am just getting my head around it. We have had a 3 day training course and it was a lot to take in, so I am just trying out a few things. I will probably end up posting quite a lot in the near future, so I do apologise

Anyway, first question:

I designed a very straight forward piece of road consisting of a centreline, 2 channels and a footway either side. I played around with superelevation, assemblies and created a corridor. This all works fine.

Now when I add a taper to my offset alignments (for instance to widen the carriageway at a junction approach in order to add a splitter island), I noticed that the corridor stays perpendicular to the centreline. So this means the 2m wide footway I specified is not actually 2m wide, measured perpendicular from the curb. (See attached)

I have figured out that I can achieve this by attaching an offset assembly to the curb and attach the footway sub-assembly to the offset assembly. (So the curb acts a bit like a subsidiary string in MX). However, in order to make this work, I need to assign the horizontal alignment and Profile of the offset alignment to the Offset in the Corridor Properties Parameters (see attached). So far I have only managed to do this by creating a temporary surface which is wider than the curbs, so I can apply a profile to the offset alignment.

This seems a bit of a silly work around for such a standard simple highway design principle. Is there an easier way to create footways that are not perpendicular to the centreline?

A few questions or suggestions:

• Why is the superelevation I have assigned to the centreline, not projected onto the offset alignments? If this was the case, the offset alignments would have had a profile automatically?
• If you attach the offset assembly to the curb, why does it not automatically know it should stay attached to the curb? ie, remove the need to specify te horizontal alignment in Corridor Parameters?
• Is there a curb subassembly in existance that will project anything attached to it, perpendicular?

Any help or suggestions are highly appreciated. Many thanks..... 

[#2]

The only way to acheive "perpendiculaity" is to use assembly offsets. And assembly offsets are not "attached" to anything even though it may appear that you have, based on one of your bullets. They always need a profile.

What I have done in your situation is not to use an assembly offset, but to use an alignment offset for your footway and use a width target within your corridor. Your footway will then be the correct width. And more importantly you will not be required to create a desing profile.

[#3]

Thanks for the reply. With alignment offset, do you mean a 2m offset from the channel line, used as a target? This should work, apart from the cross fall being applied in the wrong direction I suppose?

[#4 · Accepted solution]

Yes, that's what I mean. You're correct about the crossfall of course, but this should be a minimal difference in most cases. When the "perpendicular" angle increases, this difference becimes greater and this method may not be desirable.

[#5]

Spoiler

Hi, I´m from Sweden.

Can you explain better how to solve the problem with perpendicular "offset". By using the alignment offset and not the assembley offset. Maybe you can post any pictures?

I have a road with a bus stop on the side. How can i solve it so the ditch is perpendicular to the widening?

I´m not familiar to the term "footway".

Thanks   / Per

[#6]

I´m not familiar to the term "footway".

I believe we call them sidewalks in my part of the world.

Bill