topic Re: How can I create intersection ( T or Cross) without using Offset Alignment? in Civil 3D Forum

How can I create intersection ( T or Cross) without using Offset Alignment?

soonhui — Wed, 27 Nov 2024 07:53:17 GMT

How can I create intersection ( T or Cross) without using Offset Alignment? Is it even possible?

The installed samples and the online guide use Offset Alignment, which I don't quite like. Because my road model is actually quite simple: just one center alignment, throw in an assembly ( with simple subassemblies like lane and shoulder and daylight), maybe putting some Corridor Transition at some stations... and that's it! No need offset alignments, offset assemblies, multiple baselines... everything is single all the way.

But when it comes to intersection, is this even possible? If no, why not?

Re: How can I create intersection ( T or Cross) without using Offset Alignment?

ecfernandez — Fri, 29 Nov 2024 02:44:13 GMT

Hi @soonhui, I think we always need at least a small curb return curve, but depending on your particular case I might be mistaken. Could you please upload a plan view sketch of your intersection?

Regards!

Re: How can I create intersection ( T or Cross) without using Offset Alignment?

soonhui — Fri, 29 Nov 2024 01:19:15 GMT

@ecfernandez , this is how it would look like:

To generate corridor, we only need the main alignment for Road A and Road B to generate the long stretch ( the non-intersecting part) of the road, and we don't need the offset alignment. The offset alignment is needed only for the small curb return curve ( at the intersection).

Can I use corridor in this way?

Re: How can I create intersection ( T or Cross) without using Offset Alignment?

ecfernandez — Fri, 29 Nov 2024 02:54:26 GMT

Hi @soonhui. If you want to use the intersections wizard, you only need the two mainline alignments. From those alignments, one will be your primary road. The wizard creates offset alignments by default to model the intersection. Likewise, it creates the curb return curves. However, there is no effort beyond refining the vertical alignments that are not always the best. I think this is something good, and I would not like to get rid of it.

If you don't need the offset alignments and prefer to have the intersection as simple as possible, then you can create the design manually. You can use connected alignments to help yourself a little.

To be honest, I forgot when I last used the Create Intersection assistant. I always prefer to create my baselines and vertical alignments on my own. You should give it a try, too.

Best regards!

Re: How can I create intersection ( T or Cross) without using Offset Alignment?

nkiakas — Fri, 29 Nov 2024 13:39:41 GMT

Hi @soonhui

You need curb return or even connected alignment to model any junction.

The junction geometry and elevations depends from the edges of the travelling ways of all the alignments, because a transition (horizontal and vertical) has to be created to let the vehicle drive smooth from one alignment to the other.

Long time ago we used to create the curb return/connected alignments manual, but in recent version these alignments + profiles can be created semi automatic, with and also without the intersection wizard tool.

Regards

Re: How can I create intersection ( T or Cross) without using Offset Alignment?

chriscowgill7373 — Fri, 29 Nov 2024 15:41:38 GMT

You could use feature lines, but, those feature lines would either require manual syncing if the main line changed, or would require them to be Auto Corridor Feature lines which would take up the entire length of the corridor. With the workflows I use internally, this is something I utilize anyway, because I typically do the tie in treatments as part of separate corridors to give more flexibility on my assemblies.