A moveable bridge, or movable bridge, is a

bridge A bridge is a structure built to Span (engineering), span a physical obstacle (such as a body of water, valley, road, or railway) without blocking the path underneath. It is constructed for the purpose of providing passage over the obstacle, whi ...

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 A drawbridge or draw-bridge is a type of moveable bridge typically at the entrance to a castle or tower surrounded by a moat. In some forms of English, including American English, the word ''drawbridge'' commonly refers to all types of moveable b ...

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 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 – also known as robots in South Africa, Zambia, and Namibia – are signaling devices positioned at intersection (road), road intersections, pedestrian crossings, and other locations in order t ...

s for the road and water traffic, and moving barriers for the road traffic. In the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

, 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 A title is one or more words used before or after a person's name, in certain contexts. It may signify their generation, official position, military rank, professional or academic qualification, or nobility. In some languages, titles may be ins ...

; 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. A (double-beam) drawbridge ha ...

Drawbridge A drawbridge or draw-bridge is a type of moveable bridge typically at the entrance to a castle or tower surrounded by a moat. In some forms of English, including American English, the word ''drawbridge'' commonly refers to all types of moveable b ...

(

British English British English is the set of Variety (linguistics), varieties of the English language native to the United Kingdom, especially Great Britain. More narrowly, it can refer specifically to the English language in England, or, more broadly, to ...

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 * 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 swi ...

– the bridge deck is lifted by counterweighted cables mounted on towers; road or rail * Table bridge – a lift bridge with the lifting mechanism mounted underneath it * Retractable bridge (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 sub ...

– also called a ducking bridge, the bridge deck is lowered into the water * Tilt bridge – 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 can be rotated horizontally around a vertical axis. It has as its primary structural support a vertical locating pin and support ring, usually at or near to its center of gravit ...

– 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 structure high above carries a suspended,

ferry A ferry is a boat or ship that transports passengers, and occasionally vehicles and cargo, across a body of water. A small passenger ferry with multiple stops, like those in Venice, Italy, is sometimes referred to as a water taxi or water bus ...

-like structure *

Jet bridge A jet bridge is an enclosed connector which most commonly extends from an airport terminal gate to an airplane, and in some instances from a port to a boat or ship, allowing passengers to board and disembark without heading outside and being exp ...

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

Vlotbrug Vlotbrug (plural, ) translates from Dutch into English as "raft bridge". It is a special kind of floating retractable bridge, used at the Great North Holland Canal, which pivot either centrally or from one or both banks of a body of water to allow ...

, 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 intended ...

* Locks 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,

File:MovableBridge_draw.gif,

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

File:MovableBridge table.gif, Table bridge File:MovableBridge thrust.gif, Retractable bridge (Thrust bridge) File:MovableBridge roll.gif, Rolling bascule bridge File:MovableBridge subm.gif,

File:MovableBridge tilt.gif, Tilt bridge File:MovableBridge_swing.gif,

File:MovableBridge_transport.gif, Transporter bridge

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 The Beloeil train disaster occurred on June 29, 1864, at the present-day town of Beloeil, Quebec. A passenger train fell through an open swing bridge into the Richelieu River after the crew failed to obey a stop signal. The widely accepted dea ...

, Mont-St-Hilaire, Quebec, Canada: A

Grand Trunk Railway The Grand Trunk Railway (; ) was a Rail transport, railway system that operated in the Provinces and territories of Canada, Canadian provinces of Quebec and Ontario and in the List of states and territories of the United States, American sta ...

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 kno ...

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

Boston Boston is the capital and most populous city in the Commonwealth (U.S. state), Commonwealth of Massachusetts in the United States. The city serves as the cultural and Financial centre, financial center of New England, a region of the Northeas ...

, Massachusetts: a

streetcar A tram (also known as a streetcar or trolley in Canada and the United States) is an urban rail transit in which vehicles, whether individual railcars or multiple-unit trains, run on tramway tracks on urban public streets; some include s ...

loaded with passengers ran off an open drawbridge into Fort Point Channel near downtown Boston killing 46 passengers. * September 15, 1958 – Newark Bay, New Jersey rail accident, Elizabethport, New Jersey:

Central Railroad of New Jersey Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known as ...

(CNJ) commuter train #3314 from Bay Head Junction to

Jersey City Jersey City is the List of municipalities in New Jersey, second-most populous

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 Mobile ( , ) is a city and the county seat of Mobile County, Alabama, United States. The population was 187,041 at the 2020 United States census, 2020 census. After a successful vote to annex areas west of the city limits in July 2023, Mobil ...

, US: In heavy fog and low visibility, a disoriented towboat 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, Trade name, doing business as Amtrak (; ), is the national Passenger train, passenger railroad company of the United States. It operates intercity rail service in 46 of the 48 contiguous United Stat ...

passenger and mail train derailed while crossing the Portal Bridge over the

Hackensack River The Hackensack River is a river, about 45 miles (72 km) long, in the U.S. states of New York and New Jersey, emptying into Newark Bay, a back chamber of New York Harbor. The watershed of the river includes part of the suburban ar ...

, 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, derails 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