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Madison Street Bridge, a basculebridge over the Chicago River inChicago, IL

Moveable bridgeFrom Wikipedia, the free encyclopedia

A moveable bridge, or movable bridge (common alternativespelling in American English), is a bridge that moves to allowpassage (usually) for boats or barges.[1] In American English,moveable bridge and drawbridge are synonymous, and the latter isthe common term, but drawbridge can be limited to the narrower,historical definition used in some other forms of English, in whichdrawbridge refers only to a specific type of moveable bridge.

An advantage of making bridges moveable is the lower cost, due tothe absence of high piers and long approaches. The principaldisadvantage is that the traffic on the bridge must be halted when itis opened for passages. For seldom­used railroad bridges over busychannels, the bridge may be left open and then closed for trainpassages. For small bridges, bridge movement may be enabled without the need for an engine. Somebridges are operated by the users, especially those with a boat, others by a bridgeman (or bridge tender); afew remotely using video­cameras and loudspeakers. Generally, the bridges are powered by electric motors,whether operating winches, gearing, or hydraulic pistons. While moveable bridges in their entirety may bequite long, the length of the moveable portion is restricted by engineering and cost considerations to a fewhundred feet.

There are often traffic lights for the road and water traffic, and moving barriers for the road traffic.

In the United States, regulations governing the operation of moveable bridges (referred to asdrawbridges)[2] – for example, hours of operation and how much advance notice must be given by watertraffic – are listed in Title 33 of the Code of Federal Regulations;[3] temporary deviations are published inthe Coast Guard's Local Notice to Mariners.[4]

Contents

1 Types of movable bridges2 Visual index of moving bridges3 Accidents4 See also5 References6 External links

Types of movable bridges

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Drawbridge (British English definition) – the bridge deck is hinged on one endBascule bridge – a drawbridge hinged on pins with a counterweight to facilitate raising

Rolling bascule bridge – an unhinged drawbridge lifted by the rolling of a large gear segmentalong a horizontal rack

Folding bridge – a drawbridge with multiple sections that collapse together horizontallyCurling bridge – a drawbridge with multiple sections that curl verticallyVertical­lift bridge – the bridge deck is lifted by counterweighted cables mounted on towersTable bridge – a lift bridge with the lifting mechanism mounted underneath itRetractable bridge (Thrust bridge) – the bridge deck is retracted to one sideSubmersible bridge – also called a ducking bridge, the bridge deck is lowered down into the waterTilt bridge – the bridge deck, which is curved and pivoted at each end, is lifted at an angleSwing bridge – the bridge deck rotates around a fixed point, usually at the centre, but may resemble agate in its operationTransporter bridge – a structure high above carries a suspended, ferry­like structureJet bridge – a passenger bridge to an airplane. One end is mobile with height, yaw, and tiltadjustments on the outboard end

Visual index of moving bridges

Drawbridge

Bascule bridge

Folding bridge

Curling bridge

Vertical­lift bridge

Table bridge

Retractable bridge(Thrust bridge)

Rolling bascule bridge

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Submersible bridge

Tilt bridge

Swing bridge

Transporter bridge

Accidents

April 23, 1853 – Rancocas Creek, New Jersey: Engineer of the Camden & Amboy's 2 p.m. train outof Camden, New Jersey missed stop signals and ran his train off an open drawspan at RancocasCreek. There were 27 fatalities.

June 29, 1864 – St­Hilaire train disaster, Mont­St­Hilaire, Quebec, Canada: A Grand Trunk Railroadpassenger train failed to observe a red signal and ran through an open swing bridge over the RichelieuRiver. Ninety­nine were killed and 100 were injured.

September 15, 1958 – Newark Bay, New Jersey rail accident, Elizabethport, New Jersey: CentralRailroad of New Jersey (CNJ) commuter train #3314 from Bay Head Junction to Jersey City ran astop signal and an open derail protecting the Newark Bay 4­span lift bridge, and the train's two diesellocomotives and two of five passenger cars went into Newark Bay through one of the open spans.Four crewmen, including the engineer and fireman, and 44 passengers died by drowning.

September 22, 1993 – Mobile, Alabama, USA: In heavy fog and low visibility, a disoriented towboatpilot made a wrong turn and entered an un­navigable waterway. Due to inexperience and improperradar training, the pilot did not realize he was off­course and struck an unfinished swing bridge overthe Big Bayou Canot around 2:45AM, knocking it out of alignment by approximately three feet (onemeter), although his initial supposition in the low visibility was that one of the barges had runaground. The rails kinked but did not break, so no fault was indicated for approaching trains.Approximately 8 minutes later, an Amtrak train carrying 220 passengers derailed at the kinkedportion of the rails, killing 47 and injuring 103 more.

November 23, 1996 – Kearny, New Jersey, USA: An Amtrak passenger and mail train derailed whilecrossing the Portal Bridge over the Hackensack River, sideswiping another passenger train in theprocess. Thirty­four people were injured. A broken rail joint on one pair of the bridge's movable railsat each end of the span caused a track misalignment, while still making electrical contact with the

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Wikimedia Commons hasmedia related to Moveablebridges.

landward rails; thus signals were clear, derails closed, and a fault indication was not displayed.

See also

Bailey bridge, Medium Girder Bridge, and Armoured vehicle­launched bridge – transportable orrelocatable bridges.Barton Swing Aqueduct, a swing bridge carrying barge traffic over a ship canal.Pontoon bridge – may be built with a barge or boat­like section that may be moved for passage.Lists of rail accidents

References

1. ^ Schneider, C.C. (1907) Movable Bridges (http://books.google.com/books?id=y60SAAAAYAAJ&pg=RA1­PA153&dq=movable+bridge&hl=en&ei=fadDTKf9DsL­8Aar5I3RDw&sa=X&oi=book_result&ct=result&resnum=3&ved=0CD0Q6AEwAg#v=onepage&q=movable%20bridge&f=false), Proceeding of the American Society of Civil Engineers, Volume 33, Part 1, Page 154.

2. ^ "Part 117: Drawbridge Operation Regulations" (http://www.gpo.gov/fdsys/pkg/CFR­2006­title33­vol1/pdf/CFR­2006­title33­vol1­part117.pdf) (PDF). Title 33, Code of Federal Regulations. United StatesGovernment Printing Office. July 1, 2006. Retrieved August 9, 2013.

3. ^ "2005 CFR Title 33, Volume 1" (http://www.access.gpo.gov/nara/cfr/waisidx_06/33cfr117_06.html).Access.gpo.gov. Retrieved 2009­12­01.

4. ^ "Local Notice to Mariners – USCG Navigation Center" (http://www.navcen.uscg.gov/?pageName=lnmMain).United States Coast Guard. Retrieved 2009­12­01.

External links

Moveable Bridges in the British Isles(http://www.movablebridges.org.uk/)

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Categories: Moveable bridges

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