Mystic River Bascule Bridge

Mystic River Bascule Bridge (HM25ZP)

Location: Stonington, CT 06355 New London County
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Country: United States of America
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N 41° 21.281', W 71° 58.135'

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Built 1922

—Operated by the Connecticut Department of Transportation —

Power to raise the bridge comes from electric motors, which drive the large "Bull Wheels" connected with Linkage arms to the two plate girders which make up the lift span.
The huge concrete weights at the ends of the overhead rocking trusses counterbalance the bascule span through another set of linkages.
This configuration was patented in 1918 by the New York City Consulting Engineer, Thomas E. Brown.

Channel Width: 74 ft. 6 in.
Channel Depth: 20 ft.
Movable Span Length: 85 ft.
Total Bridge Length: 218 ft.
Roadway Width: 33 ft.
Clearance Over Roadway: 18 ft. 8 in.
Tower Height: 33 ft. 9 in.
Total Bridge Height 44 ft. 6 in.
Movable Span Weight: 664 tons
Counterweight: 285 tons each
Average Bridge Opening: 7 min.
Typical Openings: 2200 per year
Rehabilitated 2000 to 2013

The bridge was rehabilitated in two phases.
The first phase began in 2000 and the second phase began in 2010.
The goal was to restore the long term reliable operation of the bridge.
This was successfully completed in April of 2013.

Phase 1 Rehabilitation: replacement of the open grid steel deck system and sidewalk decking. Also completed structural repairs to the concrete counterweights, sidewalk supports and pier substructure.


Marker is visible beside the walkway on the Operator's House wall.
The two 285 ton counter weights seen here in "bridge open" or "down" position.

Fuss and O'Neil, Inc.

Phase 2 Rehabilitation: Complete replacement of the operator's house, operating machinery and electrical control systems.
Repairs to the structural steel, including painting of the superstructure.
All repairs were carefully designed to match the historic character of the original bridge.
For example, the electric motors were lowered into machinery pits beneath the pedestrian sidewalks in accordance with the original 1920 design.

Engineer: Transystems Corp., Close, Jensen & Miller, P.C., Stafford Bandlow Engineering, Inc., Flanders Engineering Group, Inc., LP Consultants, LLC.

Contractors: Cianbro Corporation, Gemstone LLC., Mountain Machine Works, G&G Steel, Benfield Controls.
HM NumberHM25ZP
Placed ByConnecticut Department of Transportation
Marker ConditionNo reports yet
Date Added Tuesday, March 13th, 2018 at 10:05am PDT -07:00
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Locationbig map
UTM (WGS84 Datum)19T E 251638 N 4582385
Decimal Degrees41.35468333, -71.96891667
Degrees and Decimal MinutesN 41° 21.281', W 71° 58.135'
Degrees, Minutes and Seconds41° 21' 16.86" N, 71° 58' 8.0999999999999" W
Driving DirectionsGoogle Maps
Area Code(s)860
Which side of the road?Marker is on the right when traveling East
Closest Postal AddressAt or near , Stonington CT 06355, US
Alternative Maps Google Maps, MapQuest, Bing Maps, Yahoo Maps, MSR Maps, OpenCycleMap, MyTopo Maps, OpenStreetMap

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