Vertical Curve Designer(This functionality is available with the Profiles and Design module)
Allows Vertical Curves to be Created, Examined, Edited and Deleted within Long Sections.
The Edit/Vertical Curve Designer command is accessed from the Profiles task in the long section view.
To activate this dialog box it is necessary to snap to the vertical intersection point of the long section you are interested in. You can only snap to vertical intersection points. You cannot snap to vertical curve tangent points.
Vertical Curve Designer dialog box
| Item | Used to |
| Long Section | Displays the name of the long section selected. |
| Chainage / Distance | This field displays the Chainage or Distance of the vertical intersection point selected, depending upon how the Alignment Configuration is set. |
| Elevation | Displays the Elevation of the vertical intersection point selected. |
| Design Parameters... | Opens up the Vertical Curve Design Parameters dialog box. |
| Horizontal Parabola Length | If the vertical intersection point selected has a vertical parabolic curve then the length of the curve will be displayed. To edit the curve length enter the desired length. To delete the parabola enter 0.00. The horizontal length of the parabolic curve cannot exceed twice the distance from the selected point to the nearest adjacent point. |
| K-value | If the vertical intersection point selected has a vertical parabolic curve then the K-value
will be displayed. If the point does not have a vertical curve the value will be zero. To edit
the curve enter the desired value. To delete the parabola enter 0.00. The definition of the K-value is the desired length of a curve per unit change in grade. i.e. Length = abs(KValue * ChangeInGrade); For example, for a change of grade of 5% and a K-Value of 182, the desired length is 910. Note: The K-value is only relevant to metric units. This feature is disabled unless the Configuration/Units are set to Metres. Note also that K-values are also only relevant to parabolic curves. |
| Horizontal Arc Length | This is the horizontal length of a circular curve. Note that circular curves, unlike parabolic curves are not necessarily symmetrical about the vertical intersection point. |
| Arc Radius | This is the radius for a circular curve. |
| Asymmetric Parabola Horizontal Length 1 | If the vertical intersection point selected has a vertical asymmetric parabolic curve then the entry length of the curve, before the intersection point will be displayed. To edit the curve length enter the desired length. |
| Asymmetric Parabola Horizontal Length 2 | If the vertical intersection point selected has a vertical asymmetric parabolic curve then the exit length of the curve, after the intersection point will be displayed. To edit the curve length enter the desired length. |
| Stopping Distances | This group box displays the stopping distances under various conditions. The stopping distances
are computed based upon the driver's reaction time, the speed of the vehicle, the coefficient
of friction and the grade of the road. The stopping distance is always computed for a level surface based upon the currently set Vertical Curve Design Parameters. When a vertical intersection point is selected the stopping distances are computed based upon the grades to the left and right of the vertical intersection point for travelling both up and down the grade. |
| Sight Distances | This group box displays the summit sight distance for a summit curve and the headlight distance
for a sag curve. These sight distances are computed based upon the geometry of the parabola and
the height of the driver or headlights and the object ahead. Overtaking and intermediate sight distances are also computed for level conditions. The overtaking sight distance is computed from the distance required for a vehicle to overtake another vehicle travelling at 15 km/h less than the overtaking vehicle. The intermediate sight distance is the distance required for two vehicles approaching head on at the design speed to stop without colliding, plus a safety factor of 5%. |
| OK | Creates the vertical parabolic curve based upon the Horizontal Parabola Length entered. The OK button is only active after a long section has been selected. |
| Close | Closes the dialog box. |
Note: The vertical curves are always constructed based upon the horizontal curve length. The Design Parameters can be changed at any time to display the requirements needed to satisfy the design under a variety of different conditions. For optimum conditions the sight distances should exceed the stopping distances.