This dialog box allows you to read in a new Curve Widening Table and/or change the way the table is interpreted. It is accessible from the button adjacent to the curve widening fields in the horizontal curve panel (automatic curve widening must be selected).
Select table (button)
This button (at the bottom of the dialog box) opens the Lookup Table dialog box allowing you to view, open or save the curve widening lookup table.
A curve widening lookup table contains lane width or widening values as a function of curve radius and delta (change in azimuth of the tangents). An example additive table is shown below.
First column is radius (m)
First row is delta (degrees)
body is widening value (additive)
0
20
40
90
100
180
20
0.0
1.0
2.0
2.5
3.0
3.5
30
0.0
0.5
1.5
2.0
2.5
3.0
50
0.0
0.0
0.5
1.0
1,5
1.5
80
0.0
0.0
0.0
0.5
0.5
0.5
160
0.0
0.0
0.0
0.0
0.0
0.5
50000
0.0
0.0
0.0
0.0
0.0
0.0
In the example above a curve of radius 50m with a delta of 40º will have a lane widening of 0.5m. Note that a curve with large radius or small delta requires no widening while a curve with small radius and large delta requires the most widening. Also notice that a radius below 20m is not allowed.
Type of table
Additive (radio button)
Table contains extra widths to be added to typical lane widths (see example above).
Widening values found in the table are used without modification in the curve widening fields in the horizontal curve panel.
Absolute (radio button)
Table contains total required lane width.
Typical lane width (editable field) is subtracted from the table values before they are used in the curve widening fields in the horizontal curve panel. Note that if the difference is less than zero then zero is used as the widening term.
button adjacent to the