2.0

Table Of Contents
Drawing Vertical Curves for Ditches and Transitions
225
Drawing a Vertical Curve Based on a Stopping
Sight Distance
To calculate and draft a crest vertical curve based on a minimum stopping
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 Stopping Sight option. You can also click the
Stopping Sight icon, and then click OK.
3 Select the tangents that represent the grade into and out of the PVI.
4 Enter the value for the minimum stopping distance.
To view the equations used to calculate the stopping sight distance, see
Drawing the Vertical Curves Based on a Stopping Sight Distance in
this chapter.
5 Accept the default values for Height of eye and Height of object or enter new
values at the prompts.
The Height of eye is the height of the drivers line of vision coming down the
road and the Height of object is the height of an object in the road such as an
animal, vehicle, or piece of debris. The default values for these heights 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 one.
If you enter a new length, the command recalculates the stopping sight distance
and draws the curve with the specified length.
The following illustration shows the factors used in calculating the vertical
curve based on stopping sight distance:
Drawing a vertical curve by stopping sight distance