A question came up today from our Pittsburg branch:

“How can I make Civil 3D round spot elevations to the nearest five-hundredths of a foot (0.05’)?”

I knew creating an EXPRESSION was the answer but I just didn’t know how to accomplish this task.  So after putting my noodle on the solution over the afternoon – from time-to-time when I needed a break from real work – I came up with the final expression around dinner.

Learn more after the jump…

To understand what I’m talking about look at the below image.  The spots in CYAN are everyday Civil 3D spot elevations with the precision out to the nearest ten-thousandths of a foot.  The spots in MAGENTA use the below expression to round the elevations to the nearest five-hundredths of a foot (0.05’)!

The expression:

IF(({Surface Elevation}*10-TRUNC({Surface Elevation}*10))>=0.75,(ROUND({Surface Elevation}*10))/10,(TRUNC({Surface Elevation}*10))/10)+((IF({Surface Elevation}*10-TRUNC({Surface Elevation}*10)<0.5,IF({Surface Elevation}*10-TRUNC({Surface Elevation}*10)<0.25,0.0,0.5),IF({Surface Elevation}*10-TRUNC({Surface Elevation}*10)>=0.75,0.0,0.5)))/10)

OR

ROUND(({Surface Elevation}/0.05))*0.05

for a more elegant solution (learned after this post.  Don’t I feel silly, takes the wind right out of your sail ya know.  ;)  )

Anyways, with this little beauty you can avoid spot elevations that read 100.99, 100.51, 100.01, and 100.74.  Using the expression they will round to 101.00, 100.50, 100.00, and 100.75, respectively.  🙂

A label style using this expression can be found HERE to drag into your company template.  Yes, the style uses the more elegant solution.

Thanks, and I hope this helps!