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posted 08/14/08 by Jack Strongitharm Widening Part 1

Got a scheme like this and wondering how to go about it.



Scenario
Creation of a ‘Ghost Island’ to enable safe turning into side road

What we want to do is
simply extend road surface levels to the new widened channel line and
new kerbline,
new footway and
tie into existing ground with earthwork slopes.

We have a 3D survey drawing.



You need two reference lines from the survey, so you made need to string them together, or in this case I copied them out of the drawing, joined them up and brought them back.



You need two alignments, one is the inside channel line, so the line you copied and joined together, covert to 2D
The second alignment for the widening.


Convert the existing channel 3dpolyline to a Civil 3D alignment and ensure you don’t tick ‘add curves between straights’.





Next with the existing channel edge alignment, create a profile from your ground surface, (you can just click OK rather than draw it)

Next we create an assembly, for this we need a subassembly that probably won’t be in your toolpalette, there are a lot more than you think!



So goto the catalog icon
Select Metric or Imperial and then ‘C3D Rehab’



The subassembly we will use is the ‘OverlayWidenMatchSlope1’



This is written slightly different as it does not have a left or right option, so set the ‘Insert Point Offset’ to a negative value for ‘LEFT’ and a positive value for ‘RIGHT’.
The value does not matter as we will be targeting our widening alignment for the width, so just enter a value so it shows in the assembly view. Also set the overlay to 0, for no overlay to be applied.
Then add the next features you need such as a kerb, footpath and earthwork slopes to the assembly.



Create the corridor using the Existing Left Channel Edge – Alignment as the baseline for the corridor. Start and finish the corridor distance to the limits of your widening alignment.
Set the frequency similar to the image below and include any critical chainage points as required.
An option is only calculate at a regular chainage interval rather than at the surface profile geometry points, if desired.



Next go to the targets of the corridor, and you will see that you can target the overlay subassembly to the ground surface as this will check the levels along the corridor.





From the help file, you can see that the ‘Sample Point’ is what we target for the centreline (in this case our centreline is a 3dpolyline (2009 only) and the insert point is actually our existing left edge alignment that we based our corridor on.
The width is what we will target to our widening alignment.





Result!
Much easier than working out levels and drawing profiles manually!

You can now see the potential of subassemblies much more than just standard widths and slopes.
Try moving your alignment grips around with the corridor on ‘automatic rebuild’.
Also if you want the nice colour scheme to your corridor, that is applied from the code set style as material area fill, where the users of the UK and Ireland country kit template have it already setup.

A day’s work down to minutes, with flexibility for change!

In the next part I will go through how to overlay and refine the profile level design as maybe the existing crossfall of the road is deformed from heavy vehicles etc.

Jack Strongitharm

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