The Delaware Lackawanna & Western Cedar Avenue bridge is actually two adjacent bridges
The Cedar Avenue Bridge, once called the Mattes Street Bridge, built in 1906, is typical of the plate girder bridges erected by the Delaware,Lackawanna & Western railroad during the 20th Century.[1]
Actually two bridges side-by-side, they carried passenger and freight traffic between the low-lying central Scranton yards and higher grades to the east. The bridges are located on the eastern edge of the Scranton yards, just west of the passenger station.
The freight and passenger tracks were at different heights, the passenger tracks, located on the north side, are at a higher lever than the freight tracks. The passenger track bridge is a deck plate girder bridge, while the freight track bridge is a through plate girder bridge.
In a deck bridge the plate girders are completely beneath the deck of the bridge; with through plate girders, the deck of the bridge rests on the bottom flanges of the girders, most of each girder is located above track level. This allows more clearance underneath the freight bridge, which, at a lower height, required the clearance beneath the bridge for vehicular traffic.
[1]Historians for the Delaware Lackawanna & Western Railroad: Scranton Yards Recording Project, performed in 1989, are Kathryn Steen and Amy Slaton. The drawings were delineated by Tomas Delahunty. The photographs were Mark Harrell. This project was part of the Historic American Engineering Record, a project of the National Park Service. More information can be found in the Library of Congress, HAER call number PA-132J