Moveable bridge

Madison Street Bridge, a bascule bridge over the Chicago River in Chicago, IL
The Rode Brug (Red Bridge) across the Vecht river in Utrecht, Netherlands
The Marine Parkway–Gil Hodges Memorial Bridge in New York City

A moveable bridge, or movable bridge, is a bridge that moves to allow passage for boats[1] or barges.[2] In American English, the term is synonymous with drawbridge, 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[3] 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 lights for the road and water traffic, and moving barriers for the road traffic.

In the United States,[4] regulations governing the operation of moveable bridges (referred to as drawbridges)[5] – 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;[6] temporary deviations are published in the Coast Guard's Local Notice to Mariners.[7]

  1. ^ "Boat", Wikipedia, 2023-04-09, retrieved 2023-05-17
  2. ^ Schneider, C.C. (1907) "Movable Bridges", Proceedings of the American Society of Civil Engineers, Volume 33, Part 1, Page 154.
  3. ^ "List of road–rail bridges", Wikipedia, 2023-04-15, retrieved 2023-05-17
  4. ^ "United States", Wikipedia, 2023-05-16, retrieved 2023-05-17
  5. ^ "Part 117: Drawbridge Operation Regulations" (PDF). Title 33, Code of Federal Regulations. United States Government Printing Office. July 1, 2006. Retrieved August 9, 2013.
  6. ^ "2005 CFR Title 33, Volume 1". Access.gpo.gov. Archived from the original on 2008-10-12. Retrieved 2009-12-01.
  7. ^ "Local Notice to Mariners – USCG Navigation Center". United States Coast Guard. Retrieved 2009-12-01.