Adjust the long section

[Pham Thang]

I have two long sections, A and B (Profiles A & B). In other situations, if the road is long enough, we can adjust the long section so that water flows away from the kerb. However, in this case, the long section slopes in only one direction. As a result, when the kerb return long section is created automatically, the low point always occurs within the kerb return instead of at its end.

We cannot modify long sections A and B because they must always slope down toward the left side. Although we can adjust their gradients, applying the kerb return still causes the automatic kerb return long section to place the low point inside the kerb.

I can manually adjust the kerb return long section, as shown by the blue line, but it does not form a smooth curve toward the low point at the end of the kerb. I also tried manually creating the kerb return long section by adding VIPs; however, whenever the road long section changes, I need to manually update the kerb elevations again, which is quite time-consuming.

Is there any way to automatically create a curved long section with the low point located at the end of the kerb?
https://postimg.cc/5HKrcv3d

[darren mckimm]

hi

one way would be to use a compound curve and set the bias to 1% or 99%, depending on which way it was drawn.

another way would be to put a floating from end & grade. put at the low point end and set a grade of +0.5% or +1.0% to make that end the low point, then a free connection or a max curve can be use to connect to the high end. maybe make it 1-2m long (the length of the kerb entry unit)

i added a poorly drawn parabola on the image as a guide.

daz

[Sam Cech]

I hardly every use the auto generated VG in detail design, it is only a starting point only.

If you have a road authority/council with standards for this sort of thing, it can be easier to decide what to do...

in most cases, the SW catch pit will go to the location you identified as Desired low point, practically zero need to use a curve there, I normally just use two IPs or a straight line, if I want it to match the departing road I might have a curve at that end, just need to watch out for not creating too flat of an area...

as @Darren said those percentages on compounds are useful too if you absolutely want a curve, however, it might move your low point if the grade of the road changes significantly...

cul-de-sacs are better example, often want to have a sag/crest in a specific place, so I use a fixed point or an IP and series of straights or compounds from/to each end...

automation is less of a thing in detailed design - computator elements are as close as you can get without the software reading your mind.