A moveable bridge, or movable bridge, is a

bridge A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somethi ...

that moves to allow passage for boats or barges. In American English, the term is synonymous with , and the latter is the common term, but drawbridge can be limited to the narrower, historical definition used in some other forms of English, in which ''drawbridge'' refers to only a specific type of moveable bridge often found in castles . An advantage of making bridges moveable is the lower cost, due to the absence of high piers and long approaches. The principal disadvantage is that the traffic on the bridge must be halted when it is opened for passage of traffic on the waterway. For seldom-used railroad bridges over busy channels, the bridge may be left open and then closed for train passages. For small bridges, bridge movement may be enabled without the need for an engine. Some bridges are operated by the users, especially those with a boat, others by a bridgeman (or

bridge tender A bridge tender operates and maintains a bridge to ensure the safe passage of water traffic and vehicle traffic on the bridge. For a railroad bridge, the bridge tender is also responsible for rail traffic safety. Moveable bridges A moveable ...

); a few are remotely controlled using video-cameras and loudspeakers. Generally, the bridges are powered by electric motors, whether operating winches, gearing, or hydraulic pistons. While moveable bridges in their entirety may be quite long, the length of the moveable portion is restricted by engineering and cost considerations to a few hundred feet. There are often

traffic light Traffic lights, traffic signals, or stoplights – known also as robots in South Africa are signalling devices positioned at road intersections, pedestrian crossings, and other locations in order to control flows of traffic. Traffic light ...

s 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 as ''drawbridges'') – for example, hours of operation and how much advance notice must be given by water traffic – are listed in

Title 33 of the Code of Federal Regulations Title 33 is the portion of the Code of Federal Regulations that governs Navigation and Navigable Waters within the United States. It is available in digital or printed form. Title 33 and Title 46 of the Code of Federal Regulations are usually co ...

; temporary deviations are published in the Coast Guard's Local Notice to Mariners.

Types

Double-beam drawbridge A double-beam drawbridge, seesaw or folding bridge is a movable bridge . It opens by rotation about a horizontal axis parallel to the water. Historically, the double-beam drawbridge has emerged from the drawbridge. Unlike a drawbridge, a double ...

* Drawbridge (

British English British English (BrE, en-GB, or BE) is, according to Lexico, Oxford Dictionaries, "English language, English as used in Great Britain, as distinct from that used elsewhere". More narrowly, it can refer specifically to the English language in ...

definition) – the bridge deck is hinged on one end *

Bascule bridge A bascule bridge (also referred to as a drawbridge or a lifting bridge) is a moveable bridge with a counterweight that continuously balances a span, or leaf, throughout its upward swing to provide clearance for boat traffic. It may be single- o ...

– a drawbridge hinged on pins with a counterweight to facilitate raising; road or rail **Rolling bascule bridge – an unhinged drawbridge lifted by the rolling of a large gear segment along a horizontal

rack Rack or racks may refer to: Storage and installation * Amp rack, short for amplifier rack, a piece of furniture in which amplifiers are mounted * Bicycle rack, a frame for storing bicycles when not in use * Bustle rack, a type of storage bi ...

* Folding bridge – a drawbridge with multiple sections that collapse together horizontally * Curling bridge – a drawbridge with transverse divisions between multiple sections that curl vertically * Fan Bridge – a drawbridge with longitudinal divisions between multiple bascule sections that rise to various angles of elevation, forming a fan arrangement. *

Vertical-lift bridge A vertical-lift bridge or just lift bridge is a type of movable bridge in which a span rises vertically while remaining parallel with the deck. The vertical lift offers several benefits over other movable bridges such as the bascule and sw ...

– the bridge deck is lifted by counterweighted cables mounted on towers; road or rail *

Table bridge A table bridge is a moveable bridge in which the deck moves along the vertical axis. Four hydraulic pillars under the bridge, two at each end, raise the bridge deck to allow barge traffic to pass beneath it. In contrast to a lift bridge, wher ...

– a lift bridge with the lifting mechanism mounted underneath it *

Retractable bridge A retractable bridge is a type of moveable bridge in which the deck can be rolled or slid backwards to open a gap while traffic crosses, usually a ship on a waterway. This type is sometimes referred to as a thrust bridge. Retractable bridges d ...

(Thrust bridge) – the bridge deck is retracted to one side *

Submersible bridge A submersible bridge is a type of movable bridge that lowers the bridge deck below the water level to permit waterborne traffic to use the waterway. This differs from a lift bridge or table bridge, which operate by raising the roadway. Two subme ...

– also called a ducking bridge, the bridge deck is lowered into the water *

Tilt bridge A tilt bridge is a type of moveable bridge which rotates about fixed endpoints rather than lifting or bending, as with a drawbridge. The tilting Gateshead Millennium Bridge spanning the River Tyne between Gateshead on the south bank and Newcast ...

– the bridge deck, which is curved and pivoted at each end, is lifted at an angle *

Swing bridge A swing bridge (or swing span bridge) is a movable bridge that has as its primary structural support a vertical locating pin and support ring, usually at or near to its center of gravity, about which the swing span (turning span) can then pi ...

– the bridge deck rotates around a fixed point, usually at the centre, but may resemble a gate in its operation; road or rail *

Transporter bridge A transporter bridge, also known as a ferry bridge or aerial transfer bridge, is a type of movable bridge that carries a segment of roadway across a river. The gondola is slung from a tall span by wires or a metal frame. The design has been us ...

– a structure high above carries a suspended, ferry-like structure *

Jet bridge A jet bridge (also termed jetway, jetwalk, airgate, gangway, aerobridge/airbridge, skybridge, finger, airtube, expedited suspended passenger entry system (E-SPES), or its official industry name passenger boarding bridge (PBB)) is an enclosed, ...

– a passenger bridge to an airplane. One end is mobile with height, yaw, and tilt adjustments on the outboard end *

Guthrie rolling bridge A Guthrie rolling bridge was a kind of retractable bridge, an 18th-century version of the drawbridge. It was commonly installed as the access across the narrow steep sided ditches characteristic of the polygonal forts of this era. Rolling brid ...

* Vlotbrug, a design of retractable floating bridge in the Netherlands * Linkspan *

Ferry slip A ferry slip is a specialized docking facility that receives a ferryboat or train ferry. A similar structure called a barge slip receives a barge or car float that is used to carry wheeled vehicles across a body of water. Often a ferry intend ...

Locks Lock(s) may refer to: Common meanings *Lock and key, a mechanical device used to secure items of importance *Lock (water navigation), a device for boats to transit between different levels of water, as in a canal Arts and entertainment * ''Lock ...

are implicitly bridges as well allowing ship traffic to flow when open and at least foot traffic on top when closed

Visual index

File:Drawbridge.gif, Drawbridge File:MovableBridge_draw.gif,

File:MovableBridge_fold.gif, Folding bridge File:MovableBridge curl.gif, Curling bridge File:MovableBridge_lift.gif,

File:MovableBridge table.gif,

File:MovableBridge thrust.gif,

(Thrust bridge) File:MovableBridge roll.gif, Rolling bascule bridge File:MovableBridge subm.gif,

File:MovableBridge tilt.gif,

File:MovableBridge_swing.gif,

File:MovableBridge_transport.gif,

Accidents

* April 23, 1853 – Rancocas Creek, New Jersey: Engineer of the Camden & Amboy's 2 p.m. train out of Camden, New Jersey missed stop signals and ran his train off an open drawspan at Rancocas Creek. There were 27 fatalities. * June 29, 1864 – St-Hilaire train disaster, Mont-St-Hilaire, Quebec, Canada: A

Grand Trunk Railway The Grand Trunk Railway (; french: Grand Tronc) was a railway system that operated in the Canadian provinces of Quebec and Ontario and in the American states of Connecticut, Maine, Michigan, Massachusetts, New Hampshire, and Vermont. The rail ...

passenger train failed to observe a red signal and ran through an open swing bridge over the

Richelieu River The Richelieu River () is a river of Quebec, Canada, and a major right-bank tributary of the St. Lawrence River. It rises at Lake Champlain, from which it flows northward through Quebec and empties into the St. Lawrence. It was formerly kn ...

. Ninety-nine were killed and 100 were injured. * November 7, 1916 - Summer Street Bridge Disaster,

Boston Boston (), officially the City of Boston, is the state capital and most populous city of the Commonwealth of Massachusetts, as well as the cultural and financial center of the New England region of the United States. It is the 24th- mo ...

, Massachusetts: a

streetcar A tram (called a streetcar or trolley in North America) is a rail vehicle that travels on tramway tracks on public urban streets; some include segments on segregated right-of-way. The tramlines or networks operated as public transport a ...

loaded with passengers ran off an open drawbridge into

Fort Point Channel Fort Point Channel is a maritime channel separating South Boston from downtown Boston, Massachusetts, feeding into Boston Harbor. The south part of it has been gradually filled in for use by the South Bay rail yard and several highways (specif ...

near downtown Boston killing 46 passengers. * September 15, 1958 –

Newark Bay, New Jersey rail accident The 1958 Newark Bay rail accident occurred on September 15, 1958 in Newark Bay, New Jersey, United States, when a Central Railroad of New Jersey (CNJ) morning commuter train, #3314, ran through a restricting and a stop signal, derailed, and sl ...

, Elizabethport, New Jersey:

Central Railroad of New Jersey The Central Railroad of New Jersey, also known as the Jersey Central or Jersey Central Lines , was a Class I railroad with origins in the 1830s. It was absorbed into Conrail in April 1976 along with several other prominent bankrupt railroads of ...

(CNJ) commuter train #3314 from Bay Head Junction to Jersey City ran a stop signal and an open derail protecting the Newark Bay 4-span lift bridge, and the train's two diesel locomotives 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, US: In heavy fog and low visibility, a disoriented

towboat A pusher, pusher craft, pusher boat, pusher tug, or towboat, is a boat designed for pushing barges or car floats. In the United States, the industries that use these vessels refer to them as towboats. These vessels are characterized by a squar ...

pilot made a wrong turn and entered a non-navigable waterway. Due to inexperience and improper radar training, the pilot did not realize he was off-course and struck an unfinished swing bridge over the Big Bayou Canot around 2:45AM, knocking it out of alignment by approximately three feet (one meter), although his initial supposition in the low visibility was that one of the barges had run aground. 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 kinked portion of the rails, killing 47 and injuring 103 more. * November 23, 1996 – Kearny, New Jersey, US: An

Amtrak The National Railroad Passenger Corporation, doing business as Amtrak () , is the national passenger railroad company of the United States. It operates inter-city rail service in 46 of the 48 contiguous U.S. States and nine cities in Canada ...

passenger and mail train derailed while crossing the

Portal Bridge The Portal Bridge is a two-track moveable swing-span railroad bridge over the Hackensack River in Kearny and Secaucus, New Jersey, United States. It is on the Northeast Corridor just west of Secaucus Junction and east of the Sawtooth Bridges. Ow ...

over the

Hackensack River The Hackensack River is a river, approximately 45 miles (72 km) long, in the U.S. states of New York (state), New York and New Jersey, emptying into Newark Bay, a back chamber of New York Harbor. The drainage basin, watershed of the ri ...

, sideswiping another passenger train in the process. Thirty-four people were injured. A broken rail joint on one pair of the bridge's movable rails at each end of the span caused a track misalignment, while still making electrical contact with the landward rails; thus signals were clear,

derail A derail or derailer is a device used to prevent fouling (blocking or compromising) of a rail track (or collision with anything present on the track, such as a person, or a train) by unauthorized movements of trains or unattended rolling stock. ...

s closed, and a fault indication was not displayed.

References

External links

Moveable Bridges in the British Isles

NSW moveable bridges
{{Authority control Bridges by structural type

Types

Visual index

Accidents

See also

References

External links