Roadway layout design in Civil3d

[Anonymous]

Hi All,
Since we are converting from Bentley products to Autodesk ,we are facing a serious problem with the client regarding civil3d use in roadway design so let me state our approach in design and what the client wants us to do and please share your ideas with me.

Our Current approach is :

1-we receive 2d cad road layout (concept design for example).

2- we start to draw (on 2d) the roads configuration we need.

3-start 3d modeling for the roadways based on the previously designed 2d road layout as a targets.

Our clients wants us to use civil3d fully in developing the road layouts using offset alignments and widening and similar function, and not to use any 2d road layout again.

my question is :

which approach you guys following ?!
if you have any advantages and disadvantages of both please mention them.

[GZE]

For us it depends on project type. We use 2d lines for urban road projects only it easy for us to use them as target for corrido model. For rural projects we use fully corridor model with ofset alignments for widening etc

[Pointdump]

Salah,

"...and not to use any 2d road layout again"

An Alignment is basically 2D. It doesn't have Elevations. A Corredor adds a Surface and Profile to the Alignment to get 3D. So I'm not understanding your question. Can you elaborate a little?

Dave

[Anonymous]

Hi Dave,

what I mean is " not to draw the layout in 2d lines and poly lines anymore "

they want us to draw the layout using the alignments so every single line in the layout should be replaced by alignment and if you have any changes in the layout you have to change the geometry of that alignments.
I understand that the alignments are basically 2d elements but my concern is I do not think that drawing by offset alignments and widening tool are as flexible as drawing polylines and trim them and fillet them some times,

offsetting polylines and deforming them is so easy compared by doing this for alignments.
Hope I clarified enough

[Pointdump]

Salah,

"... I do not think that drawing by offset alignments and widening tool are as flexible as drawing polylines..."

One of the great tragedies of being an employee is having to do things the way the boss tells you to do them. I grieve with you.

Dave

[AllenJessup]

We use Alignments, Profiles and Corridors. The advantages are that all the information is 3D, so that it contains elevation information and can be used getting volumes, also any changes in profiles or templates are immediately shown forward through the design without the need for re-drafting and recalculation. For new roads this is straight froward. For rehab projects it takes a little tweaking.

[Anonymous]

Hi Allen,

we are using corridor modelling as well but those corridors to target the layout polylines.

My question was do you follow the same approach by having the layout in polylines and do the modelling afterwards or you are using offset alignments to draw the layout ?!

[ksorsby]

I guess it depends on what the actual work is, but from my experience (in the UK) you always need a 2d xref of your base road layout anyway as this also forms the basis of other non-Civil 3D drawings and is often requested by other non-Civil 3D-using project consultants both internally and externally. Sending a Civil 3d-only model is of no use to a landscape architect or planner for example.

Plus, some things will just take much longer to develop in Civils and you'll never get alignments to always do exactly what you need to do so, as you say, basic 2d elements are much more user-friendly. 

Every company I've worked for over the last 10 years will always have a 2d xref as the base plan for which the detailed highways corridors are based on and targets where necessary.

Kevin

[AllenJessup]

We use both techniques. It's usually an offset but in tight circumstances (usually in a rehab project) we will target Featurelines draw in 3D to accomplish what we want.

[ksorsby]

Yes, I'd say that featurelines are a good halfway house and are very usable these days for developing layouts. But even then, a bunch of featurelines isn't much use to the client or planning architect without me exploding them, and then that defeats the point.
I wish everything could be done in Civils though, but I'm not sure it's feasible on anything involving more than one company.
Kevin

[fcernst]

This is definitely the way to go.

Your engineers will thank you because the 2D geometry will finally be consistently correct.  Widening transition curvature/reverse curvature design is efficient and accurate..Curb return design is faster, and from then on subsequently easily editable.

It is a nightmare as a design engineer trying to design from handed down 2D linework. Always requires clean up and slows up the project...

[Joe-Bouza]

I prefer this method of alignments as the flat work, but having coworkers behind the curve makes it tough; they dont get the hole idea of c3d.

Here is why I prefer it: once you get the hang of it you can get geometry changes to ripple to infinity and beyond. But more importantly - Labeling.

If you set up you alignment labels to do it all you'll never be troubled with surface labels having to be relocated again. I have yet to perfect it but in theory I'm certain it is what the software developers intended

[Cadguru42]

We use a combination of 2d and 3d. For the initial work and for actual construction documents we use 2d polylines for the layout of the project. I don't know how you guys using just alignments for everything can get things like driveway aprons, handicap ramps, and intersections to look correct for plan production let alone the overhead of having that many alignments. Sounds like a nightmare. 

We have a design drawing that has the proposed layout XREF'd into it. That is where we create proposed surfaces, corridors, feature lines, etc. It's never used for sheet creation. We used to use the XREF'd polylines as targets until the bugs with 2015/2016 and targeting XREF polylines, figures, etc. showed up. Now I have to create corridor target alignments by hand in the design drawing because of that, which slows down production by a lot. I doubt Autodesk will fix them anytime soon, either, based on the way support reacted. 

[ksorsby]

I'd say that engrtech's way is pretty much the way all the companies I've worked for work, makes a lot of sense and is robust.

I'd also agree that Civils just isn't there yet for shifting round ramps, junctions, existing constraints, parking bays and the like on the fly using alignments. I kind of think it's great for basic preliminary work and real nut-and-bolts detailed design but there's this middle ground like we've been discussing where it just seems to lack functionality and useability.

Kevin

[fcernst]

...I'd also agree that Civils just isn't there yet for shifting round ramps, junctions, existing constraints, parking bays and the like on the fly using alignments.

Below was done quickly using only the capabilities of an offset alignment...ready to profile to prove gutter drainage to plan reviewer.

gg

gg

[ksorsby]

That does look good, certainly more that I've achieved with them. The difficulty comes when somebody says 'layout's changed, move it 20m further along, add another recess, add a buildout on the south side and a new junction on the north side which comes in at about 15 degrees. And we need it in in half an hour'.

I could do that in half an hour in vanilla cad, Civils not so much.

I do agree that offset alignments are more powerful than I give them credit for though.

Kevin

[MikeEvansUK]

I Always trace an alignment over the base plan (produced by others) if it it exists so the tools can check on the fly.

I find Architects layouts and some times planning consultants layouts full with errors. Re-alignment tests the planning design and removes issues on the fly. Feature lines are fine for targets but care must be taken as they also can create or be created from geometry which is incorrect (tangentially etc).

As for Offset alignments, I always only use these to detail the main linear widenings then change them to centreline or kerb return alignments and manually tie them back into the proposed/existing correctly. I have found It's too cumbersome and a waste of time to try using offsets and widenings to tie into existing edges or detail every little deviation, it's quicker to detail these manually.

There are a lot of missing tools/geometry or tools (reverse curves, 3 compound curves, roundabout tool etc) which are incorrect to uk design logic so I have always tended to manually design the road edges where necessary. I would only use featurelines in the case of existing ground features (not roads) or to enable a bank or verge to transition from one grade to another.

I would agree with the client to blindly follow the base plan for the main geometry (centreline & channels) and assuming it is geometrically correct would be a mistake.

M

[fcernst]

...The difficulty comes when somebody says 'layout's changed, move it 20m further along, add another recess, add a buildout on the south side and a new junction on the north side which comes in at about 15 degrees. And we need it in in half an hour'.

"Oh that's no problem Sir....done.  All curves and tangents are tangential, and the north gutter profile has been dynamically extracted for your review, Sir."

[ksorsby]

That certainly looks more complex and useful than I thought possible with widened alignments. If you wanted the junction (to the left) to come onto the widened area where the channel curvature is, will the channel offset alignments for that road fillet and tie in nicely with the channel offset alignment shown on the north side? My point being, a key thing in generating 100% civils linework is getting channels to play nicely with each other and that's easy in cad. My understanding is that it won't, you would have to use the junction tool each time and that tool has its own set of issues.

Apologies, not intending to hijack the thread but this is related to the benefits of using Civil 3D to generate highway linework rather than using vanilla cad! 

Cheers,

Kevin

[fcernst]

You're incorrect on all accounts again..

Better stick with your Vanilla Design team..  😉