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posted 01/19/07 by Jack Strongitharm Sight Distance Analysis Part 2

This week I will continue to develop this technique to rather than a pass or fail but to how much the design is failing by or how much clearance there is.

From last week we were left with a feature line that was positioned to check a forward sight and was draped to the surface at each end. Then raised in level to the appropriate heights for standards.

We then will use surfaces to analyse the depths, i.e. cut and fill (sounds familiar, nothing is ever that hard!)

1. Create a grading from the line and offset a short distance such as 1m and at 0 change in level on both sides of the feature line.
Create a surface and style to not display the surface (so your screen does not get cluttered)




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2. Create a tin volume surface from the composite model that was created earlier


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3. Change the style of this surface to a 2D Solid Banding



4. Then choose the analysis tab of the surface properties and select two ranges


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5. Change the ID 1 to a maximum level of 0, and ID 2 minimum level of 0. Change the purple colour if you wish to green.


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Now red will signify a clash or fail and green for pass! (This is also how to shade cut and fill as it is the same technique!)


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As you can see the design fails on the earthworks as we found before and to any designer this means reduce the amount of cut, increase the horizontal curve or create some widening around the bend.

6. Now we can also find out the actual failure amount by either adjusting the style to a contour style or by turning on the contours on this one and draw a contour line to display the labels


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Contour style

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Shaded style but with contours

7. Finally you can simply see the depth from the tooltip


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As you can see a little out of the box thinking can give you a lot more because Civil 3D is very flexible.

Jack Strongitharm

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