This bridge is a movable retractile bridge (a real “draw bridge”) built in 1899 by the Berlin Iron Bridge Company (which can be seen in the steel over the roadway).
This type of bridge is mounted in a skewed position on trucks or carriages on one side of a body of water. To open the channel to waterway traffic, the bridge is “retracted” or withdrawn to a place out of the navigation channel by the use of cables and pulleys.
How it Works
The two separate spans each moved diagonally along the track to open to boat traffic. It basically rolls back using the tracks and rollers. These bridges are mirror images of each other and are each structurally separate.
Things to Notice
This bridge is actually two separate bridges. Each are oblique and open to traffic in that way.
This bridge was where the worst Boston public transportation accident ever occurred in November of 1916 when a streetcar went through the gate when the bridge was open and plunged off of it killing 47 people.
It is the only bridge of it’s kind left in the United States (never a popular style).