I am working on a project and could use some help. I have a line shapefile that I need to buffer. The trick is that I, ultimately, need the buffer to be exactly the width and length of a roads polygon layer, so that we can tabulate the area of road work that has been completed .  

Of course, I can buffer the line by a distance, say 10 feet, and the result is a polygon 10' wide and the length of the line feature.

I then need to go in and manually edit the vertices, adding new vertices as needed, to snap the buffered polygon to the exact dimensions of the roads polygon layer.

I know that I can go in and change the buffer distance for each polygon, but with the varying dimensions for the roads poly, there is too much variability. 

I am really trying to find a quicker way to perform this work, without digitizing each piece of road poly that I need. 

Thank you all,

Jay