Superelevation

Superelevation describes the cross slope of the road, while gradient describes the slope along the road. When gradient and superelevation are combined, this is referred to as the resulting slope.

Where can I find the dialog?

The dialog is available in the tool for road alignment and cross-section parameters.

Using the Dialog

When constructing vertical curvature, the user receives continuous information about the maximum gradient allowed on the road. The line element is marked in red if the requirement is exceeded.

The minimum resulting slope ensures drainage on the road. However, when building up superelevation, it may still occur that the resulting slope becomes 0 m/m.

A* = Gradient, B = Cross slope/superelevation, C* = Resulting slope

Maximum resulting slope can occur on steep sections with superelevation buildup in curves.

The design library can also calculate superelevation along the road alignment. This is done with the Generate parameters from road class... function found in the cross-section parameters dialog (automatic method).

A* = Roof slope, B* = One-sided slope

The superelevation function contains values in a diagram that describes the maximum superelevation as a function of curve radius.

Example

Slope (m/m)	Radius (m)
0.05	60
0.03	100

The table shows that the value 0.05 applies up to a radius of 60. Between 60 (0.05) and 100 (0.03), the values are interpolated, and for radii over 100, 0.03 is used.