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Chapter 3 Working with Profiles and Vertical Alignments
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Creating a Vertical Alignment at an Offset Based
on a Horizontal Alignment
Use the Alignment option of the Define by Offset/Grade command to offset a
vertical alignment based on the offset distance(s) between two selected
horizontal alignments. The alignment that you offset can be the finished
ground centerline or any left or right ditch or transition. The alignment that is
created can be any left or right ditch or transition.
The Alignment option is useful in situations in which a constant offset distance
would not work, such as where there are vertical curves in profile view and/or
passing lanes (irregular offset distances) in plan view.
To use this option, a horizontal alignment must exist that corresponds to the
vertical alignment you want to reference and the one you want to create. These
two horizontal alignments are used to calculate the offset distances along the
profile that, when applied to the change in grade value, results in the new
vertical alignment definition.
To create a vertical alignment at an offset that is based on a horizontal
alignment
1 Define a horizontal alignment centerline.
2 Define offsets for the horizontal alignment, such as left and right edges of
pavement. You must define these offsets as alignments as they are created.
3 Draw and define at least one finished ground vertical alignment (for example,
the finished ground centerline).
4 From the Profiles menu, choose DT Vertical Alignments ä Define by
Offset/Grade.
The following prompt is displayed:
Select offset type (Uniform/Alignment) <Alignment>:
5 Type A to select the Alignment offset type.
The following prompt is displayed:
Profile to reference (Center/Left/Right) <Center>:
6 Do one of the following to select the vertical alignment to offset:
n
Type Center to offset the finished ground centerline alignment. If you select
this option, then you must select the corresponding horizontal alignment.
Either select the alignment from the graphics screen, or press ENTER to
access the Alignment Librarian dialog box and select the alignment.
n
Type Left or Right to offset a left or right profile. If you select either Left or
Right, then you must specify which left or right profile (or ditch) you want
to offset. The following prompt is displayed:
Select left profile (Ditch/1/2/3/4/5/6/7/8):
n
Type D for Ditch or a number from 1 to 8.
Next, you must specify which horizontal alignment this profile corresponds
to from which to calculate the offsets. Either select the alignment from the
graphics screen, or press ENTER to access the Alignment Librarian dialog box
and select the alignment.