How To Reverse an Alignment

This question comes up periodically - I recorded a video to cover it today.

The question is if I have keyed in an alignment, and I want to reverse the alignment can I do that quickly and easily in TBC. The answer is it depends on the alignment and the geometrical elements of the alignment.

Ask these questions

  1. Does the alignment have any Station Equations defined

  2. Does the alignment have any Superelevations defined

  3. Does the alignment include geometry elements including Spirals or Asymmetrical Vertical curves

If the answer to all the above is NO then you can use Convert to Linestring command to convert the alignment to a linestring and then reverse the linestring and then recreate the alignment using the linestring - you will need to set the start station of the HAL to the correct station value in the editor, and you will need to open the profile view for the VAL and then use the Move command to move it from its current start station of 0 to the correct start station

If the answer to any of the questions is Yes then there is no easy way to reverse a spiral or an asymmetrical curve or station equations. however what I would do then is to use the current geometry as input guides for the new alignment (snap to points etc.) (at least in the horizontal)

Video shows you how