Offset Crv help

Hello -

I’m trying to offset a series of curves in one direction (X) without changing the Z length of the curve. Ran into a question with my idea of how to do this; The curve that offset doesn’t stay consistent in length, any suggestions on how to maintain its length? or at the very least keep it from getting shorter?

Thank you!

mexico city (10.0 KB)

You could extend it, use Extend Curve. By same length you surely mean that you want your curve to stay between 2 parallel line. So extend it with enough length then cut it.
There is no geometry internalized in your file.