UPDATE: New Corridor Transitions in Civil 3D 2023 and beyond have somewhat solved this problem.. Although with some bugs..

You can’t really transition in a way that is simple, like 12d, LDT, MX etc.

You can change the slope easily, but not transition easily! I.E Cubic, Linear transition etc.

A few methods you can use include the following.

Use the Superelevation editor??

Click on the subassembly that you want to transition (The Daylight) and select a super elevation mode say “Left Outside Lane”.

Then select your corridor and add a superelevation view

Then go through the cumbersome tabular editor to populatd the grades on the graph.Should look like so.

The finished results looks a little like so, which is somewhat alright, but still not nice, as the transition is linear. And we get jagged edges on the contours.

Use the Override Stations Method.

Select the corridor and go to the section editor

Select the Parameters Editor and modify the grade.

Then apply to the station range I want.

Still only gets me halfway there, as there is no transition options!!, the only way to force the transition from here is to change the sampling on the corridor reducing the quality of the transition anyway!

Do It manually by working out the location on the surface you need to widen to. But that is just not realistic!

Use a fixed link and link the grade in the fixed link to the daylight link. Also horribly cumbersome, but gets the best result.

Draw a Profile that represent grade so (elevation of 0.4 = 40% etc.)

Add a link with elevation target to your assembly like vertical elevation. Make sure it is added before your daylight link or this wont work

Next Select your Assembly go to its properties and select the construction tab, you need to link your daylights slope to your fake links elevation

Finally target the elevation profile with your new elevation link and watch the magic happen.

Looks the best, and it is dynamic, but extremely infuriating to setup.

Kapanther

Original Post Here