This workflow will demonstrate how to create a “best fit” centerline alignment between two edge of pavement horizontal alignments.

For this example, there are two existing horizontal alignments.  One represents the left edge of pavement (shown in green), and one represents the right edge of pavement (shown in red).

1. Display these two alignments using the command Geometry > View Geometry > Horizontal Annotation.  Make sure to turn on the options to “Display as Complex Linestring” and “Planarize”.
   
   
   
   
2. Within MicroStation, use the Move/Copy Parallel command to create offsets of the two alignments to the outside of the originals.
   
   
   
   
3. Use the InRoads command Surface > Design Surface > Set Elevation to set the elevation of the two new linestrings to an elevation of 10’.
   
   
   
   
4. Now you have the two original alignments at elevation of zero and two offset alignments at elevations of 10’.
5. Use the command Surface > Design Surface > Generate Longitudinal Feature to create the best fit centerline feature.
6. On the Generate Longitudinal Feature dialog, click on the Controls tab.  Set the Horizontal Method to “Project Two Slopes”.
7. One the Main tab, set the interval, set the feature style to “breakline” and toggle on the Generate Graphics Only option.
   
   
   
   
8. Click Apply.  You are prompted to “Identify First Element for Slope 1”.  Select the original left edge of pavement and accept.
9. You are prompted to “Identify Second Element for Slope 1”.  Select the offset to the left edge of pavement and accept.
10. You are prompted to “Identify First Element for Slope 2”.  Select the original right edge of pavement and accept.
11. You are prompted to “Identify Second Element for Slope 2”.  Select the offset to the right edge of pavement and accept.
12. You are prompted to “Identify Reference Element”.  Select the original left edge of pavement and accept.
13. You are prompted to “Identify beginning>Reset for Entire”.  Click the reset to accept the entire left edge of pavement.
14. You are prompted to “Identify beginning>Reset for Entire”.  Click the reset to accept the entire left edge of pavement.
    
    
    
    
15. This graphic can be imported as the centerline alignment using the command File > Import > Geometry.  On the From Graphics tab, set Type to Horizontal Alignment.  Key in a name for the alignment.
    
    
    
    
16. Click apply to identify and accept the centerline graphic.