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Purpose

To design one string such as a channel related to a Master String as fixed by offset and gradient. This works in a more simple way than Strings, Define or Edit and is a very useful tool. Remember that the Master String only exists when you combine a Horizontal Alignment (normally a 2D Polyline) with a Vertical Alignment (.vtg file).

 

Operation

Pick the Horizontal Alignment. If a Road name has been assigned with menu item Design, Horizontal, Extract geometry and a previous menu item such as Strings, Draw has been run then the .vtg file used appears as a default in the Road details dialogue – if not select the vertical geometry file (the Master String now exists).

 

Draw 3D Polyline    

Outputs the string as a 3D Polyline

 

Write report file    

Outputs comprehensive 3D report (.kdr).

 

Write section file    

Outputs a .sek file for superimposing on vertical alignment section.    

 

Horiz. Vertices    

"On" to calculate at Horizontal Alignment 2D Polyline vertices.

 

Vert. Vertices    

"On" to calculate at Vertical Alignment Tangent Points.

 

Draw and section interval    

Enter interval to calculate offsets. 1.000 for typical use.

 

Report interval    

Enter interval for report file. 10.000 for typical use.

 

Layer    

Set layer to draw 3D Polyline on.

 

Enter the Start and End chainage values that the string will be calculated over or use the Pick chainage < buttons to fix these from the drawing. Enter the offset and gradient values to define the string. Note that if start and end offsets and gradients are different this will be a linear change – use menu item Strings, Define or Edit if a more appropriate method of change is required i.e. a Cubic Reverse Curve.

 

The .kdr design report file looks like this :-

 Chainage            E               N         Level     Offset  Level diff.

 

   52.500        2120.181        2248.527     93.772     -3.650     -0.091

   52.760        2120.372        2248.351     93.772     -3.650     -0.091

   60.000        2125.693        2243.266     93.737     -3.650     -0.091

   70.000        2132.761        2235.962     93.660     -3.650     -0.091

   80.000        2139.491        2228.343     93.548     -3.650     -0.091

   82.500        2141.119        2226.391     93.515     -3.650     -0.091