Changing alignment starting station

[Anonymous]

Hello everyone,

I've encountered a problem, when I draw the alignment, my starting point is at the top-right corner (+0+000m) and form a closed loop. I want to make the starting point at the bottom-left corner, and have changed it as (+0+000m). However, some of the stations along the alignment appears to have negative value (i.e. -0+423m).

How can I at the same time make the station at the bottom-left corner as (+0+000m) and appears no negative value stations along the alignment?

Thank you.

[Todd_Rogers]

Change the Reference Point under your Station Control in Alignment Properties.

[Anonymous]

Thanks for your reply. I've changed the reference point, but the station information starts with negative number. When I add the alignment label, some negative number will appear. So how can I　deal with such issue？

[Todd_Rogers]

Can you post the drawing?

[Anonymous]

I got the label like this. Bottom-left corner with 0 and increase clockwise, but after reaching the original starting point, the number start to decrease.

[cwr-pae · Accepted solution]

The problem is based on the way alignments exist as single entities. Alignments are actually Cartesian in nature, everything is based on a straight line and offsets from that line. When you move the 0+00 point, the line is still there, with the same total length and anything before the new 0+00 point will be considered negative. To 'fix' the alignment you have to remove the part before station 0+00 and recreate it starting at the far end (highest station remaining) and drawing towards 0+00 from there.  You could probably try playing games with station equations to make the negative stations read as higher station, and the station above 0+00 would need an equation to read lower. but I think that would be asking for confusion.

If I had to do that I would explode the alignment, create a small gap before where I wanted 0+00 and recreate the alignment, closing the gap after creation.