It is possible to reshape/resize overpass parallel to existing line in red color. Overpass is shown in dark color..
One way it could be done is by editing the data to make 2 parallell copies of the existing line (red) - one copy on either side. Then cut them to the desired length.
About making a parallell copy of a line:
ArcGIS Help 10.1
Chris Donohue, GISP
