So I am a basic Bentley MXROADS user who is use to doing designs string based (often with input files) but we have been told we need to start learning Civils 3D which will replace all our current Civils software (in theory) and combine it into one. I was sent on an essentials course which was very good and went through all the very basics but when I came to actually try a very simple job (add a small simple junction to an existing road) I come to a complete hault.
I have managed to take my survey (a 3D dxf) and turn into a good surface fine and I have created the alignment/profile for the new junction fine (in exactly the same way I would do it in MX). What I am not sure about is how to create the radii (or curb returns if you will) especially in terms of tieing into existing levels. I have looked on the internet at examples of peoples solutions but they all seem like alot of excessive effort and bodging. One example I saw was trying to use the intersection tool (I'm not a fan of relying on 'wizards' to do tasks) but it still seems so excessive and like a bodge for such a simple job which would take 5 minutres in MX.
I feel like I am missing something fundimental here so I am hoping someone can explain to me the correct way to do it in Civils 3D.
Regretably there is no simple way to model intersections with corridors in Civil 3D. To model an intersection you will need an alignment and profile for each curb return and an alignment and profile for the edge of pavement for the main road at each side of the intersection. You will also need several assemblies to handle the portions that must transition to form the intersection. Prior to the intersection wizard all of these pieces had to be created and managed manually.
The intersection wizard does 2 things that make this process less tedious. First it automatically creates all the alignments and profiles for you. Second, it creates dynamic associations to the alignments and profiles so that the intersection will automatically update when the horizontal or vertical geometry changes for the intersecting roads. It also allows you to change the curb return and widenings for acceleration and deceleration parametrically.
While the intersection wizard is a great help, the entire process is still cumbersome, and even more so in cases where the wizard is incapable of handling the geometry. If you are going to use Civil 3D you will have to accept this workflow. There are a couple of 3rd party add ons that make the process easier if you are open to considering that option. A search for Civil 3D products should help you in that regard.
Thanks for the great reply, it confirms and clears things up abit. What I didn't want to do is waste time learning an incorrect way to do it when there was a better way. I expected that the corridors and radii would need to be managed manually without the intersection tool but I think it's ashame it doesn't design the levels (like in MX) automatically between two feature lines, keeping tangency. Infact I really don't like how the intersection tool doesn't even attempt to maintain tangency in the intersection, it almost seems lazy to me.
I assume that if this was to be done manually then you would create offset alignments upto the radii and then design the profiles for the radii, presumably you can see the channel line in the profile view and not just the existing surface (assuming you haven't created a corridor yet)? Is it possible to create dynamicness manually?
I shall give it all ago anyway, thanks.
I'll clarify my comment about the intersection being dynamic when you use the wizard. When you create an intersection object, Civil 3D creates a dynamic link between the profiles of the roads at the intersection. Thus if you change the profile of the main road, the side road will update to maintain vertical tangency. This linked relationship applies when you create the intersection object. It is not necessary to create the rest of the intersection if you only want to link the centerlines.
You can also use the wizard to create automatic dynamically linked curb return alignments and profiles. The wizard creates the profiles for you. Thereafter the curb returns are dynamic to changes in the horizontal and vertical geometries of the roads. If the alignments move or the widths of the lanes change the curb returns and profiles update to maintain tangency. Thus the wizard serves to maintain all the horizontal and vertical geometries for you.
One of the limitations here is should you need to make manual edits to the curb return profiles, those edits are not dynamic to changes in the roads. For example if you need to set a high or low point along the curb return profile, you can do that manually by editing the profile created by the wizard. However if you then cause the road profiles to change, the curb returns will stay tangent at the ends but the high or low point will not change. You will have to make those edits manually.
So the wizard does provide fully automated dynamic intersections within the limitations of the tool.
If you do not use the wizard then the alignments and profiles of the curb returns will not be dynamic to the road lanes and will have to be designed and maintained manually. By extending the curb return alignments a short distance along the road lanes you can then display a piece of the road lanes in the profile and use those as a guide for designing the curb returns.
I guess I will have to just try and use the intersection tool as much as I can if I'm going to use Civils 3D, I have noticed that at least one person has managed to use it to create a simple junction without modelling the whole existing road. It really does shock me that with all the intelligence and dynamicness I was shown that something as simple as this is so manual if you don't use the wiozard, it's almost like taking a step backwards.
When I mentioned tangency I was referring to how it creates the profiles for the minor road and the curb returns, I really don't like the fact they are not created tying in tangentially to the road they are joining (bare in mind I'm from the UK and we don't continue the crown line through to the major road). I know in terms of the crownline it's not vital to match the main roads crossfall but it would be nice to have that option and it certainly shouldn't set it at more than about 5% gradient change. As for the curb returns the fact it designs them as a straight line (as far as I have seen) is just a big no no for me, I can't see how that is acceptable but maybe it's just me.
As impressed as I am with many features of Civils 3D I just hope I can overcome these shortcomings and find a way to make up for them and get the job done at least as good as I currently do.
Thank you for the great advice and explanations anyway.
I suggest you spend a little more time getting acquainted with the tools. There is an option to create a "blended" intersection where the main road and side road crowns meet at the junction point. There are also options to constrain the side road crown line profiles to min/max grades within a specified distance as they approach the intersection.
Granted the tools are not ideal and there are definite limitations but you may not be aware of their full capabilities.
Thanks for the advise, I think that is exactly what I will do, just play about with it until I can create a design I like efficiently.
When I had to learn Microstation, I spent six months in hell. Finally got it, and the trick is, allow yourself to think in the alternative interface. I'm not saying there isn't a fundamental difference, just that, if you're in the position where you are required to deal with several programs, think of them like different people, and then, figuring out the details should even be enjoyabe.
Yes I think you are right, I'm not new to having to know more than one platform but it's never easy when something you use for so long and take for granted is taken away..In MX I would design the alignment (horizontal and vertical the same as Civil 3D), offset to create my channels and then tell it to design the radii between the channel lines and he existing surveyed channel line, it positions them and designs the levels for me so the whole process takes minutes.
I shall bare with it until I get there.
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