Large box culvert structures

User Q & A (Post Here)
1

Has anyone got a workflow for modelling roads with large box culverts.
I’m looking for a clean way to

  1. use single side slope command that will interface the OG but also tie to back of headwall surface when culvert is present. ( i have alot of condition commands to build terracing through this area, relying on side slope height)
  2. x sectional fill area to be exclude where culvert surface is present.

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thanks guys

2

Possibly create 3D lines using the Side Slope tool to get those back strap and add those lines to the Corridor. This maybe a combo of different commands.

1 Like
3

Hey Peter,

A couple of thoughts;

  1. Apply more conditionals. As you mentioned, your terracing is dependent on the current side slope height, I would remove that side slope from FG (and relabel it as reference or target). That way it stays existent in the typical but you have the ability to override. Then there have quite a few options for conditionals. Possibly run one as a connect to the target node in standard circumstances and another to either target surface or back of headwall line string during a condition change?

  2. Boxes are rarely perpendicular to the road. So modeling that excavation in a Corridor would not be very clean. When I used to verify plan quantities on big boxes, I would build the entire excavation manually from the bottom of the hole up with a series of subgrade surfaces. When it came to the box itself, i would create the plane of material below the box (top of bedding), set a line string at the base of the box, and then offset inward (a very small amount, maybe .005’) and adjust that line string to the height of the box. This required the creation of quite a few surfaces, but gave some pretty great quantities for structure backfill, if that is what you are after. I would work this into my corridor to tie them all together. Or possibly have a staged EG, where you have this surface with box set but without backfill merged into the EG (Personally, I would probably merge the stage where structure backfill was complete into the EG). That way I could manage my surfaces/qtys for each box (if there are multiple) and the roadway would capture separate roadway work items. Typically placing that material over the pipe [structure backfill] is separate work item than standard embankment fills for the road.

4

Hi Peter,

I know this might be a long shot, but I wanted to throw an idea your way. Could you model the culvert itself and use the trench excavation feature to define where the roadway tie data should conform? Essentially, this would allow you to use utility commands to create both the necessary “void” for embankment deductions (within the box and concrete) and a surface that interacts with your design.

In my section below, the red surface represents what you’d need your culvert surface to be, essentially the point where your roadway slope would tie into the culvert surface. Would this approach work for your case? Let me know your thoughts!

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