2.0

Table Of Contents
Chapter 3 Working with Profiles and Vertical Alignments
224
Drawing a Vertical Curve Based on a Passing
Sight Distance
To calculate and draft a crest vertical curve that is based on a minimum passing
sight distance.
1 From the Profiles menu, choose DT Vertical Curves to display the Vertical
Curves dialog box.
NOTE
You can only use this option with a crest curve.
2 In the Description list, select the Passing Sight option. You can also click the
Passing Sight icon, and then click OK.
3 Select the tangents that represent the grade into and out of the PVI.
4 Enter a value for the minimum passing sight distance.
To view the equations used to calculate the passing sight distance, see Drawing
the Vertical Curves Based on a Passing Sight Distance in this chapter.
5 Press ENTER to accept the default values for Height of eye and Height of object,
or enter new values.
The Height of eye is the height of the drivers line of vision coming down the
road; Height of object is the height of a vehicle approaching the driver. The
default values are set in the Profile Value Settings dialog box.
The length of curve is calculated.
6 Press ENTER to accept the calculated length of curve value, or enter a new value.
The passing sight distance is then calculated.
The following illustration shows the parameters used in calculating a vertical
curve based on minimum passing sight distance:
Drawing a vertical curve by passing sight distance