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Mystic River Bridge,
Bridge No. 362
• Route 1 over Mystic River
• Groton - Stonington
• Steel balance-beam (Brown patent) bascule
• Length: 4 spans, 223' overall, 85' bascule span
• Built in 1922
• Thomas E. Brown, engineer
• American Bridge Company, fabricator
Few bridges are as much fun to watch in operation as the Route 1 bridge in Mystic, because unlike
many bascules, its mechanical parts are all out in the open. Power to raise the bridge comes from
electric motors, which drive large "bull wheels" connected with linkage arms to the two plate
girders which make up the lift span. Huge concrete weights at the ends of overhead rocking trusses
counterbalance the bascule through another set of linkages.
This configuration was patented in 1918 by New York City consulting engineer Thomas E. Brown.
Besides being economical to build, the design had many advantages: accessibility of major parts
for maintenance, automatic braking of the bridge at the top of its movement, latitude for imprecise
motor control, and distribution of the bridge and counterweight forces onto separate piers. It also
suited its setting well, since the low level of the crossing relative to high tide would have made it
difficult to put the mechanism and counterweight below the road. The project immediately won high
praise for Brown's design, and Mystic River Bridge was featured in several engineering journals
and textbooks of the period.
Upgrading Route 1, the road along Connecticut's shoreline, was the top priority of the Connecticut
Highway Department following World War I. This bridge was one of the last links in that effort.