2.0

Table Of Contents
Chapter 3 Working with Profiles and Vertical Alignments
228
The following illustration shows the parameters used in calculating a vertical
curve based on headlight data:
Drawing a vertical curve by headlight data
Drawing a Sag Vertical Curve Based on a
Given Velocity
To calculate and draft a sag vertical curve with given grades and design velocity
1
From the Profiles menu, choose DT Vertical Curves to display the Vertical
Curves dialog box.
NOTE
You can only use this command with a sag curve.
2
Select the Comfort option and click OK.
3
Select the tangents that represent the grades coming into and out of the PVI.
4
Enter the design velocity.
5
Press ENTER to accept the default value, or enter a new value.
The command calculates the appropriate length of the curve. To view the
formula used to calculate the length of the sag vertical curve, see Drawing the
Sag Vertical Curve Based on a Given Velocity in this chapter.
6
Press ENTER to accept this length, or enter a new value.
If you enter a new length, the Comfort option recalculates the design velocity
and draws the curve with the length specified.
The command draws the curve and displays the final design velocity. If you use
metric units, the command displays a default of 88.51 kmh, the equivalent of
55 mph.