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Corridor Template - Reference Surface wrong vertically?

Question asked by Alan Sharp on May 21, 2020

I got this issue raised to me today so I thought I would capture it here for all to be aware of. The problem was identified by a User. They had built a Road Model as two corridors. One corridor for the left side, the other corridor for the right side. They referenced the surface of the Left Side model in the Right Side corridor, and vice versa for the Left Side corridor. at one specific station, if you reviewed the Cross Section of the road in the cross section editor, the elevations on two nodes either side of the center line were identical. If you viewed the same station in the Template editor for either of the corridors, the Corridor was in the right place vertically but the reference surface was off vertically - in the example reviewed by ~0.2’. The issue was reported as a bug.

Turns out it was not really a bug. The Geospatial Team added Tunnel capability in the 5.3 release and in that addition they added a setting in the Project Settings - View - Corridor Template View in the top section called Display Perpendicular. This is so that if you are working with Tunnels where the cross sections are typically computed perpendicular to the alignment you can show the cross sections perpendicular to the alignment. If you set this to Yes then the Perpendicular Calcs are activated. For most normal roads they are computed vertically so you want this set to No


In this case the user had changed this to Yes and that was what was causing the erroneous display on reference files - it was showing like a bug because in the Tunnel Template Editor - the Tunnel Design is normally computed perpendicular to the alignment, so the corridor model that you show inside the tunnel also needs to be perpendicular to show the correct geometrical relationship - and then they would match, however in this case the Road Model is correct because it is computed vertical, however the reference surface was being computed perpendicular, and because there was a reasonable slope at the station in question, the reference surfaces were off by 0.2’.

Good catch - I was not aware of the setting addition, the user did not know how or when they set the setting that way - but they are good to go now.