Being Civil

Why My Profile View Grid Looks So Strange?

It’s not very uncommon that Project Managers change the beginning and end stations of an alignment. The request may come in early designing phase or after most of the work on the drawing done and after the profiles were being cut. Changing start station of the alignment is really not a task that should create any trouble to anyone, but if there are objects depending on the alignment, they may get pretty “confused” about the change. Here is the scenario:

After the manager’s request  the alignment start station is changed from 630+00 to 0+00.  Setting new station in Alignment Properties will update the stations.

 

In a plan view it all shows fine and the alignment stations update accordingly, but profile views get pretty messed up (see picture below). To see how to address this after the jump.

ANALYZING HGL WITH TAIL WATER CONDITION

I would like to show a very simple yet commonly mistaken procedure committed by many SSA users with tail water condition at the outfall of the system. Below is a screenshot of a profile plot with fixed water elevation at the outfall, however the profile plot shows a different HGL where one would expect the HGL to match the fixed water elevation i.e. 980 ft. for this model.

Figure 1. Profile Plot for tail water at the outfall @ 980 ft. using Kinematic wave routing.

The reason for the above profile plot reporting a Max HGL at outfall as 977.40 ft. is due to Kinematic wave routing used for the analysis which provides a non-linear reservoir formulation for channels and pipes, including translation and attenuation effects that assume the water surface is parallel to the invert slope. It does not account for backwater effects or flow reversals.

The key to analyzing any tail water, flow reversal or looped network is to analyze with Hydrodynamic routing method. It solves the complete St. Venant equations throughout the drainage network and includes modeling of backwater effects, flow reversal, surcharging, looped connections, pressure flow, tidal outfalls, and interconnected ponds.  

Notice the change in the Max HGL for the same profile plot when using Hydrodynamic routing method. The Max HGL reports at 980 ft. at the outfall that match the Tail water elevation as expected.

Figure 2. Profile Plot for tail water at the outfall @ 980 ft. using Hydrodynamic routing.

I hope this helps. Stay tunned for more tips to come.

 

 

 

 

 

Profile Views Have Gap in Grid

This is a quick post that can easily go into a category of “A-ha”.  An image is worth thousand words-they say. This one is not worth that many but it will surely show what the issue is:

 

If you take a look at the Profile View you quickly noticed that something is not right. The profile view has a gap in the middle of it. To see how to fix this gap, click on continue.

Pipes Look Like Octogons? FACETDEV

Have you ever came across your pipes in section view and they look like octagons rather than the nice 12” RCP that you drew in plan view? If so this is caused by the setting FACETDEV described in the HELP menu: Networks in Profile and Section Views

The number you specify for facet deviation defines the maximum distance from the chord to the arc—the chord being an edge that is created from faceting the curve to the true mathematical arc. The facet deviation has a range of greater than zero (0) and no upper limit. The lower this variable is set, the more segments will be used to draw the pipe. The minimum number of segments is 8.

 

 

Hope this helps!

 

Building Intersections With Profile Constraints

I recently had a customer asking how Civil 3D determined how to adjust profiles when locking them together to build an intersection. Specifically, what if you had a constraint in place for the secondary road profile (travel at –2% for 100’ from the main road centerline, for example.) Does the main road profile move to match the secondary road profile, or does the secondary road profile arbitrarily move to match the main road profile? As it turns out, you have options here, you just have to know where to go to set them. Find out more after the jump.

AutoCAD Civil 3D 2012 Preview: Alignment Enhancements

With a focus on transportation, there are quite a few enhancements for alignments in the new release of Civil 3D. This particular post is going to cover a lot of very high-level overview type information regarding alignments, and will be broken out into individual posts that will dig more deeply into the subjects over the coming month. To see what some of the new features are, follow the link!

My Profile Data has Shifted!

If your workflow requires you to have multiple viewports set at different scales on a single layout tab, you may have noticed that the profile data appears to have shifted.

This should only occur if you have viewports on the same layout tab set to different scales, say one at 1”=20’ and 1”=60’. This is known issue with Civil 3D 2011 that is currently being looked into by our Development team. However if you activate each viewport separately and type the REGEN command, you should now see the desired results.

Hope this helps!

Why can’t I remove my Profile?

Occasionally, you want to create a new Surface Profile from an Alignment that already has a Profile associated with it.  If you have multiple Profiles created, they will be listed below.  You may notice the “Remove” button down below, but why won’t this actually remove a Profile?

Well, it does remove Profiles, but only ones that are created while you are in that dialog box.  It is removing, not deleting.  So how do you actually delete a Profile, then?  Easy – find it in Prospector, right-click and then delete.

Of course, if you simply want to remove the Profile from the View, but not delete it, then you can uncheck the option to draw it, both at the time you create the View, or in Profile View Properties, afterwards.