Tuesday, 2 October 2012

River Sections - Culverts

This post  is a follow on from a previous post about an add on we are developing for Civil 3D. In that post we looked at commands for creating and annotating river cross sections. The following video looks at the command used for drafting culverts on the longitudinal section. The command allows the user to select data from the cross sections to draft the long section view.

One of the issues when surveying culverts along a reach is that (depending on culvert length, surveyor access and a number of other issues) the two ends of the culvert may not be surveyed on the same day or by the same field crew. Another is that the two ends of the culvert may have completely different shapes and picking up what the surveyor perceives to be the crown, invert and top of parapet for each end may not be that straight forward in the field. More often then not the best approach is to survey each end of the culvert, draft these up in cross section and then use the cross section views to provide information for drafting the culvert in long. section.

As you can imagine measuring points from the culverts on cross section and then transferring this information to the long. section is time consuming. The following video shows a custom command that enables users to select points from cross section for the start and end of the culverts and automatically drafts the culvert on long section using this information. There is also a second tab in the dialog box for creating bridges - this uses a similar approach in that users select points to define the bridge dimensions from cross section and the command inserts a dynamic AutoCAD block on the long section. The block is sized and scaled correctly to suit the information pulled from the cross section.

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