How to add intervals from csv file that have no coordinates


I have created a civil 3d file by importing points from csv file that represent edges of the bridge - north and south.
Each of these points is connected by the line and i need to add revision clouds that represent material testing from the excel sheet. This file contains start station and end station. Start station is the distance from the north point by a certain amount of inches, Station end is the distance from the north point as well.
For example:
Start point - 100"; End point - 200"; That gives an interval of 100" on the line that needs to be represented by adding a revision cloud aligned with the line in order to show where the material is off from the norm.
I was wondering if anyone has an idea on how to speed up this kind of work instead of doing it all manually.
Thank you!