This dialog box allows you to simplify vertical curves. This is performed using two different actions; Merging Curves and Vertical IP Reduction.
Merging Curves
In a vertical alignment, adjacent curves with similar K values can be merged together to form a singular curve. This routine will merge curves that follow two rules:
1. Their intercurve station distance are within the user-supplied tolerance, expressed in project units.
2. They are relatively similar in K value, expressed in percent (%) change.
Example: Suppose there are three adjacent curves A (K = 10), B (K = 5) and C (K = 14) in a vertical alignment whose intercurve distances are within tolerance. Consider the following two choices of K similarity values, in percent change:
In choosing a value of 100%, only curves A and B will be merged. This is because the K of curve A is within a relative change of 100% to the K of curve B. However, curve C will not be merged since the change in K values between curve B and C is greater than 100%.
Increasing the K similarity value to 200%, all three curves (A, B and C) will be merged to form a singular curve.
Note: Only curves of the same kind (crest or sag) will be considered. Adjacent curves with K values of opposing sign will be ignored.
Vertical IP Reduction
Location represents vertical curves as a polyline, connecting the start station to end station with VIPs in between. The VIP reduction component uses the Ramer-Douglas-Peucker algorithm to simplify the curve while preserving the general geometry of the polyline, up to a tolerance. This reduction tolerance represents the largest deviation that the simplified polyline will have from the original, expressed in project units.
Relative change in K values between adjacent curves. Two curves, A and B, will be merged if the relative change in K values between curves A and B are less than or equal to the similarity tolerance when expressed in percent.
Intercurve tolerance
The maximum station distance between curves to be considered as adjacent (for merging purposes).
Simplification tolerance
The maximum offset from the simplified profile to the original profile (in project units).
