Adding Vertical Curves
Updated November 15, 2017
This article applies to:
- RoadEng Civil
- RoadEng Forestry
Vertical curves are very similar to horizontal curves: you first identify a VIP, and then you define a curve between the tangents it defines. Vertical curves are created and edited using the vertical curve panel.
In Location, File | Open <RoadEngCivil>\Location\Align stage 2.dsnx.
Restore the Vertical Curves panel (figure next page).
Figure 1: Vertical Curves Panel with Automatic Curvature Selected
Use the Previous IP or Next IP buttons to move to the second VIP in the alignment (watch the Profile window).
Press the Get Default Curve button . Then press the Apply button to create the first curve.
Use the Next IP button to move to the third VIP in the alignment.
Again, press the Get Default Curve button . Notice that you are warned that the curve does not fit the tangents and the Apply button is disabled (figure below).
Figure 2: Curve Warning
Note: When a curve does not fit tangents (vertical or horizontal), you can either:
a. Shorten the curve.
b. Shorten the previous and/or next curve.
c. Move intersection points to reduce the angle between tangents or to lengthen the tangents.
In this case, as the curve is already defined as the shortest curve allowed for 40 mph (auto is checked), the only way to shorten the curve (without changing VIP locations) is to reduce the speed.
Change the Design Speed 20; notice that the error goes away.
This speed is too slow (the whole point here is to increase the design speed of this section of road). Instead we will lower the third VIP elevation to reduce the grade change.
Go to the Profile window and move the third VIP down a bit. In the Vertical curve panel, again press the Get Default Curve button . The error should have gone away. Press Apply.
Return to the Profile window and edit the third curve VIP. Right Click in profile window| Add/Edit IP Tool | Left Click on intersection point at VC 3 to capture it. Move the VIP up and down the curves will update dynamically as you move the mouse.
Note: The current cross section is shown in the Profile window as a red cross. When you have finished editing a curve, the current cross section is the End Vertical Curve (EVC) point.
Continue editing all the VIPs until you get this middle point as high as possible (Figure next page). Keep the first and last segments tangent to the original road.
Figure 3: Vertical Alignment after Curves Applied
\You should also try to make the mass haul balanced. Mass haul is covered in more detail in following exercises.
Note: To delete multiple points on the alignment or entire alignment click on Home |Delete Range button. In you uncheck the All Points box and check Profile (Vertical IPs) to delete the entire profile.
File button | Close. Do not save changes.