Haraz Rah Consulting Engineer Group

The Sarah Mildred Long Bridge is a lift bridge that carries the US 1 Bypass over the Piscataqua River between Portsmouth, New Hampshire and Kittery, Maine. The bridge is a double deck truss bridge, with the US 1 Bypass road deck above and a railroad bed below.

The bridge features two separate movable spans. While the main lift span and its towers are the obvious primary moving feature, the second moving span is only apparent to water and rail traffic. On the north side of the bridge, the first non-trussed section of rail bed lifts up and moves south as a retractable bridge, coming to rest on top of the rail tracks inside the truss. This creates a waterway large enough for most recreational boats to pass through without the need for interruption of automobile traffic on the bridge.

Given its life span, a replacement bridge is currently in the works.
http://en.wikipedia.org/wiki/Sarah_Mildred_Long_Bridge

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