This is original to the line, as far as I can tell. The date (1907) is right. This two span concrete bridge for the CSX (formerly Clinchfield) over Reedy Creek is just off Industry Drive in Kingsport, near the new roundabout on Netherland Inn Road. (There’s a new span that takes the line over Center Street as it intersects Netherland Inn Road. I vaguely remember the old span, which was just a two-lane overpass. There are remnants of the old concrete structure still in place up on the line.)
This span actually no longer carries the weight of the line, it’s been strongly reinforced. It you go by this now, you’ll see the Greenbelt covered bridge going through the left span.
Blogging the Railroad Tunnels 