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Bridge No. 507
• Glen Road (Route 816) over Housatonic River
• Newtown-Southbury
• Steel Parker through truss
• Length: 300'
• Built in 1934
• Connecticut Highway Department, engineers
The State Highway Department built several long-span trusses in the 1930s. Where the terrain was fairly flat, and river conditions made construction of intermediate piers difficult, state engineers chose large trusses rather than open-spandrel concrete arches or multiple spans. 
The Parker truss was a common choice for bridges of this length. The curved top chord gave the truss greater depth in the middle, where it was needed most, and thus saved material over a straight-chord Pratt truss of comparable size. The Parker truss was, however, somewhat more complicated to engineer and fabricate.
The bridge was built as part of the State Highway Department's ongoing trunk-line improvement program. Prior to the construction of Interstate 84, Glen Road carried Route 6, one of the state's major inland east-west routes. The traffic on Route 6, including large numbers of trucks, was second only to the shoreline Post Road. Only a substantial bridge such as this could suffice for Route 6's Housatonic River crossing.
The bridge's railing and deck were replaced in the 1980s.
