Guthrie rolling bridge
Encyclopedia
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 fort
s of this era.
Rolling bridges were unhinged, and remained horizontal as they were retracted within the gates of a fortification http://www.palmerstonforts.org.uk/gloss.htm, similar in operation to a modern thrust bridge.
Two such bridges are installed at Fort Nelson, Portsmouth
, United Kingdom
.
Retractable bridge
A retractable bridge is a type of movable bridge in which the deck can be rolled or slid backwards to open a gap for crossing traffic, usually a ship on a waterway. This type is sometimes referred to as a thrust bridge....
, an 18th century version of the drawbridge
Drawbridge
A drawbridge is a type of movable bridge typically associated with the entrance of a castle surrounded by a moat. The term is often used to describe all different types of movable bridges, like bascule bridges and lift bridges.-Castle drawbridges:...
. It was commonly installed as the access across the narrow steep sided ditches characteristic of the polygonal fort
Polygonal fort
A polygonal fort is a fortification in the style that evolved around the middle of the nineteenth century, in response to the development of powerful explosive shells....
s of this era.
Rolling bridges were unhinged, and remained horizontal as they were retracted within the gates of a fortification http://www.palmerstonforts.org.uk/gloss.htm, similar in operation to a modern thrust bridge.
Two such bridges are installed at Fort Nelson, Portsmouth
Fort Nelson, Portsmouth
Fort Nelson, in the civil parish of Boarhunt in the English county of Hampshire, is one of five defensive forts built on the summit of Portsdown Hill in the 1860s, overlooking the important naval base of Portsmouth. It is now part of the Royal Armouries, housing their collection of...
, United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
.