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Movable BridgesMovable Bridges
Earl Dubin, P.E.St t l E iStructural EngineerNew York Division
Federal Highway Administration
Movable BridgesA vehicular bridge that can beopened to allow passage of aopened to allow passage of a
waterborne vessel
li blEarliest Movable BridgesBridges
Tomlinson Bridge• New Haven, Connecticut• Built 1797• Timber draw
l bl idEarly Movable Bridges
Small Draws or SwingsTimberTimber
Hand operatedNarrow channelsNarrow channels
Short life span
Early Movable Bridges
BasculesNo center pierNo center pierFaster opening
More compact designMore compact design
bl idMovable Bridges
Vertical LiftsErie Canal BridgesErie Canal Bridges
Larger spans in early 1900’s
Types of Movable BridgesBridges
Vertical LiftsVertical LiftsVehicular deck is raised to allow
vessel passage
f blTypes of Movable BridgesBridges
BasculesVehicular deck pivots from
horizontal position to vertical orhorizontal position to vertical ornear vertical position
Early Movable Bridges
BasculesScherzer rolling liftScherzer rolling lift
Trunnion lift – Ferry Street
f blTypes of Movable BridgesBridges
SwingsSwingsVehicular deck pivots in the
i ihorizontal plane creating twochannels for vessel passage
Variable Frequency Drives
VFDs - Primarily control motor dspeed
Fl V t D i t l dFlux Vector Drives – control speed and torque
AASHTO Design Specifications
Section 8 – Electrical Design
8.6.1.5 – Variable Frequency Speed Control
“…In general, variable frequency drives should not be used for movable bridge drives.”
AASHTO Design Specifications
8.6.1.5 – Variable Frequency Speed Control
“ fd h li it d“…vfds have seen limited success…have historically lacked the ability for precise control ofthe ability for precise control of torque at low speed.”
ffi / l fTraffic/Vessel Safety DevicesDevices
SignalsSignals Barriers/Gates
GGongsNavigation Lights
Fender systems
Safety Interlocks
Signals to redGates lowered
Barrier loweredBarrier loweredAll Clear Signal
Open BridgeOpen Bridge
Inspection Guidelines
AASHTO’s Movable Bridge Inspection, Evaluation and Maintenance ManualEvaluation and Maintenance Manual
Complex BridgesComplex Bridges
• Inspection• Inspection Procedures
• Inspector training and gexperience
Annual Bridge Washing-Vegetation/Debris Removal
S t P i tiSpot PaintingMechanical LubricationWearing Surfaceg
NYC Movable Bridge Projects
Willi A $620 M UnderWillis Avenue $620 M Under construction
3rd Avenue $150 M Completed in 20073 Avenue $150 M 2007
145th Street $80 M Completed in 20062006
MaCombs Dam $180 M Completed in 2005
$1.03 Billion
- Name the three primary types of movableName the three primary types of movable bridge.-What is the name of the Engineer who designed the first vertical lift bridge in the US?- Where was it located?
-Swing bridges can be rim bearing or bear onSwing bridges can be rim bearing or bear on what?-Early types of drawbridges provided access to what types of structures.
Homework – visit the four movables in theHomework visit the four movables in the City of Buffalo
- Name- Type - Condition
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