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

Types

* Double-beam drawbridge * 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 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 – 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 – 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 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 p ...

– 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-like structure * Jet bridge – 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, nl, vlotbruggen) translates from Dutch into English as "float bridge". In its broadest sense, it includes pontoon bridges. In a narrower sense, it includes floating swing bridges which pivot either centrally or from one or both ...

, a design of retractable floating bridge in the Netherlands * Linkspan * Ferry slip * 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, Drawbridge File:MovableBridge_draw.gif, Bascule bridge File:MovableBridge_fold.gif, Folding bridge File:MovableBridge curl.gif, Curling bridge File:MovableBridge_lift.gif, Vertical-lift bridge 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, Submersible bridge File:MovableBridge tilt.gif, Tilt bridge File:MovableBridge_swing.gif,

File:MovableBridge_transport.gif, Transporter bridge

Accidents

* April 23, 1853 –

Rancocas Creek Rancocas Creek is a tributary of the Delaware River in southwestern New Jersey in the United States. The creek's main stem is long, with a North Branch of and a South Branch flowing .U.S. Geological Survey. National Hydrography Dataset high- ...

, New Jersey: Engineer of the

Camden & Amboy The United New Jersey Railroad and Canal Company (UNJ&CC) was a railroad company which began as the important Camden & Amboy Railroad (C&A), whose 1830 lineage began as one of the eight or ten earliest permanent North AmericanList of Earliest Am ...

'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 St-Hilaire train disaster occurred on June 29, 1864, near the present-day town of Mont-Saint-Hilaire, Quebec. A passenger train fell through an open swing bridge into the Richelieu River after the crew failed to obey a stop signal. The wide ...

, 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 rai ...

passenger train failed to observe a red signal and ran through an open swing bridge over the Richelieu River. Ninety-nine were killed and 100 were injured. * November 7, 1916 - Summer Street Bridge Disaster,

Boston Boston (), officially the City of Boston, is the capital city, state capital and List of municipalities in Massachusetts, most populous city of the Commonwealth (U.S. state), Commonwealth of Massachusetts, as well as the cultural and financ ...

, 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 ...

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 (CNJ) commuter train #3314 from

Bay Head Junction A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a gulf, sea, sound, or bight. A cove is a small, circular bay with a narr ...

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 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 over the Hackensack River, 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