World Library  
Flag as Inappropriate
Email this Article

Bascule bridge

Article Id: WHEBN0000843482
Reproduction Date:

Title: Bascule bridge  
Author: World Heritage Encyclopedia
Language: English
Subject: List of bridges in the United Kingdom, Drawbridge, Industrial Canal, Bridge of Lions, Hanover Street Bridge
Collection: Bascule Bridges, Bridges
Publisher: World Heritage Encyclopedia

Bascule bridge

Bascule bridge
This animation shows the movement of a double leaf bascule.
This animation shows the movement of a double leaf bascule.
Ancestor Drawbridge, Plate girder bridge, cantilever bridge
Related Lift bridge, swing bridge
Descendant None
Carries Pedestrian, automobile, truck, light rail, heavy rail
Span range Short
Material Steel
Movable Yes
Design effort Medium
Falsework required Site and prefabrication specific

A bascule bridge (commonly referred to as a drawbridge) 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 or double leafed.

The name comes from the French term for balance scale, which employs the same principle. Bascule bridges are the most common type of movable span because they open quickly and require relatively little energy to operate, while providing the possibility for unlimited vertical clearance for marine traffic.


  • History 1
  • Types 2
  • Gallery 3
  • See also 4
  • References 5


Tower Bridge, London.

Bascule bridges have been in use since ancient times. However, it was not until the adoption of steam power in the 1850s that very long, heavy spans could be moved quickly enough for practical application.


Animation of a rolling lift bridge (such as the Pegasus Bridge)

There are three types of bascule bridge designs,[1] and counterweights required to balance a bascule's span may be located either above or below the bridge deck.

The fixed-trunnion (sometimes a "Chicago" bascule) rotates around a large axle that raises the span(s). The Chicago bascule name derives from the location where it is widely used, and is a refinement by Joseph Strauss of the fixed-trunnion.[2]

The rolling lift trunnion (sometimes a "Scherzer" rolling lift), raises the span by rolling on a track resembling a rocking chair base. The "Scherzer" rolling lift is a patented refinement by the American engineer William Donald Scherzer.

The rarer Rall type combines rolling lift with longitudinal motion on trunnions when opening.[3] It was patented (1901) by Theodor Rall.[2][3][4] One of the few surviving examples is the Broadway Bridge (1913), in Portland, Oregon.[3][5]


See also


  1. ^ Koglin, Terry L. (2003). "4. Bascule Bridges". Movable bridge engineering. John Wiley and Sons.  
  2. ^ a b "Landmark Designation Report: Historic Chicago Bridges" (PDF).  
  3. ^ a b c Wood Wortman, Sharon; Wortman, Ed (2006). The Portland Bridge Book (3rd Edition). Urban Adventure Press. pp. 32, 35.  
  4. ^ "Patent number 669348: T. Rall movable bridge".  
  5. ^  
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.