I'm assuming you're wanting to find the distance from the blue line to the pink lines?

What i've done previously is create a perpendicular line to the blue line and make sure that extends beyond the distance of the pink line - https://community.safe.com/s/question/0D54Q000080hOR7SAM/creating-lines-perpendicular-to-linear-features

Then you can split the perdendicular line by the pink lines. Now you can spatially relate the perpendicular lines back to the blue line (so you'll get rid of any that aren't used) and calculate the length of the perpendicular lines

Actually i wanted the total pink to pink. But i suppose i could just 2x what you suggest.

i am trying to determine the best location to get the perpendicular. and it looks like i will have to hope that the center point doesn't ever land on a condition like the above.

While using the 0 index would be easy i see at least 2 conditions where not know whether to perpendicular left or right would miss the edge i want to intersect. like this and this.

and the first example. to the right would yield correct results while to the left would yield several hundred feet.

I found 3 more reasons to try something else.

1. the centerline is not always centered so i would not get an accurate 1/2 width.
2. there are many features i would need to find rules to filter out.
3. in this case my gestimate of using 50 to make the first snip would miss the row.

it got exponentially more difficult. turns out sometimes the centerline is there and other times it is in another featuretype. and then i found that in some cases they are both there. so testing if there is b use it. if b is not there test to see if a is there. if a & b are there always use b.