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In architecture, a starling (or sterling) is a defensive bulwark, usually built with pilings or bricks, surrounding the supports (or piers) of a bridge or similar construction. Starlings may be shaped to ease the flow of the water around the bridge, reducing the damage caused by erosion or collisions with flood-borne debris. They may also form an important part of the structure of the bridge, spreading the weight of the piers.

The term cutwater is used for such a structure shaped with water flow in mind, as a pier or starling with a diamond point.^[1] A starkwater is a bulwark against ice floes.

Depending on their shape and location, some starlings may accumulate river debris, mud and other objects, potentially creating navigational hazards or hindering downstream water flow.

Shape

Starlings may form part of a buttress for the vertical load of the bridge piers, so would typically be symmetrical. Other symmetrical starlings may be used on tidal stretches of rivers because of bi-directional flow, requiring dual cutwaters; at low tide, Old Wye Bridge, Chepstow, on the Welsh border, can be seen to have cutwaters on both ends of the piers and their foundations. Cutwaters may also be provided downstream to reduce riverbed scour. Other starlings may be asymmetrical, with only an upstream cutwater, the downstream end being flat or rounded.

The starling has a sharpened or curved extreme, sometimes called the nose. The cutwater may be of concrete or masonry, but is often capped with a steel angle to resist abrasion, focusing force at a single point to fracture floating pieces of ice striking the pier. In cold climates, the starling is typically sloped by about 20 to 45° from vertical, so current pushing against part-submerged ice tends to lift and shear it;^[2] this can be known as a starkwater.^[3]^[4] This is distinct from a sloping top to shed the rain.

On a narrow bridge, a cutwater shape can be carried up to the top of the parapet, to provide a pedestrian refuge.

References

^ "cutwater". Encyclopaedia Britannia. Retrieved 4 April 2024.
^ Urquhart, Leonard Church (1959). Civil Engineering Handbook (4th ed.). New York: McGraw-Hill Book Company. pp. 8–75.
^ Raymond, William G.; Riggs, Henry E.; Sadler, Walter C. (1937). The Elements of Railroad Engineering (5th ed.). New York: John Wiley & Sons. p. 163.
^ Fowler, Charles Evan (1929). The Ideals of Engineering Architecture (1st ed.). Chicago: Chicago Gillette Pub. Co. pp. 179–195.

[1] "cutwater". Encyclopaedia Britannia. Retrieved 4 April 2024.

[2] Urquhart, Leonard Church (1959). Civil Engineering Handbook (4th ed.). New York: McGraw-Hill Book Company. pp. 8–75.

[3] Raymond, William G.; Riggs, Henry E.; Sadler, Walter C. (1937). The Elements of Railroad Engineering (5th ed.). New York: John Wiley & Sons. p. 163.

[4] Fowler, Charles Evan (1929). The Ideals of Engineering Architecture (1st ed.). Chicago: Chicago Gillette Pub. Co. pp. 179–195.

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+{{Short description|Support structure in engineering}}
-{{accuracy|date=April 2019}}
+[[File:Tower Bridge 4.jpg|thumb|The starlings of [[Tower Bridge]], London, are clearly seen beneath the roadway.]]
-{{About|the architectural term|the bird species|Starling}}
+In [[architecture]], a '''starling''' (or '''sterling''') is a defensive [[bastion|bulwark]], usually built with [[deep foundation|pilings]] or [[brick]]s, surrounding the supports (or [[Pier (architecture)|pier]]s) of a [[bridge]] or similar construction. Starlings may be shaped to ease the flow of the water around the bridge, reducing the damage caused by [[erosion]] or collisions with flood-borne debris. They may also form an important part of the structure of the bridge, spreading the weight of the piers.
-[[File:LondonTowerBridge2004-08-03.jpg|thumb|The '''starlings''' of [[Tower Bridge]], London, are clearly seen beneath the roadway]]
+The term ''cutwater'' is used for such a structure shaped with water flow in mind, as a pier or starling with a diamond point.<ref>{{cite web |url=https://www.britannica.com/technology/cutwater |title=cutwater |publisher=Encyclopaedia Britannia |access-date=4 April 2024}}</ref> A ''starkwater'' is a bulwark against ice floes.
-In [[architecture]], a '''starling''' (or '''sterling''') or, more commonly, '''cutwater''' is a defensive bulwark, usually built with pilings or [[brick]]s, surrounding the supports (or [[Pier (architecture)|pier]]s) of a [[bridge]] or similar construction.  Starlings may be shaped to ease the flow of the water around the bridge, reducing the damage caused by [[erosion]] or collisions with flood-borne debris, and may also form an important part of the structure of the bridge, spreading the weight of the piers. The term cutwater especially applies for bulwarks that are relatively effective in that way.  A '''starkwater''' is a bulwark specifically against ice damage.
-[[File:Flood debris on Bywell Bridge - geograph.org.uk - 1114579.jpg|thumb|left|upright|Seasonal flood debris accumulated above a starling]]
 Depending on their shape and location, some starlings may accumulate river debris, mud and other objects, potentially creating navigational hazards or hindering downstream water flow.
-{{-}}
 ==Shape==
+[[File:Chepstow Bridge - geograph.org.uk - 288954.jpg|thumb|[[Old Wye Bridge, Chepstow]], low tide, looking upstream.]]
-[[File:IMG 3978 bridge piers.jpg|thumb|Asymmetric bridge piers on the [[Canalside Rail Trail Bridge]], [[Deerfield, Massachusetts]], with the upstream face both angled and reinforced against heavy water, high water, and ice floes]]
+Starlings may form part of a [[buttress]] for the vertical load of the bridge piers, so would typically be symmetrical. Other symmetrical starlings may be used on tidal stretches of rivers because of bi-directional flow, requiring dual cutwaters; at low tide, [[Old Wye Bridge, Chepstow]], on the Welsh border, can be seen to have cutwaters on both ends of the piers and their foundations. Cutwaters may also be provided downstream to reduce riverbed [[bridge scour|scour]]. Other starlings may be asymmetrical, with only an upstream cutwater, the downstream end being flat or rounded.
+The starling has a sharpened or curved extreme, sometimes called the nose. The cutwater may be of concrete or masonry, but is often capped with a steel angle to resist abrasion, focusing force at a single point to fracture floating pieces of ice striking the pier. In cold climates, the starling is typically sloped by about 20 to 45° from vertical, so current pushing against part-submerged ice tends to lift and shear it;<ref>{{cite book |last=Urquhart |first=Leonard Church |title=Civil Engineering Handbook |publisher=McGraw-Hill Book Company |edition=4th |date=1959 |location=New York |pages=8–75}}</ref> this can be known as a ''starkwater''.<ref>{{cite book |last1=Raymond |first1=William G. |last2=Riggs |first2=Henry E. |last3=Sadler |first3=Walter C. |title=The Elements of Railroad Engineering |publisher=John Wiley & Sons |edition=5th |date=1937 |location=New York |pages=163}}</ref><ref>{{cite book |last=Fowler |first=Charles Evan |date=1929 |title=The Ideals of Engineering Architecture |url=https://babel.hathitrust.org/cgi/pt?id=mdp.39015014100849&seq=11 |edition=1st |location=Chicago |publisher=Chicago Gillette Pub. Co. |pages=179–195}}</ref> This is distinct from a sloping top to shed the rain.
-Starlings may form part of a buttress for the vertical load of the bridge piers, and for that purpose would typically be symmetrical. Examples such as at the [[Old Wye Bridge, Chepstow]] are on lower stretches of rivers which are tidal and that require a starling in both directions. Other starlings may be asymmetrical, so that the upstream aspect of a pier is larger as it a face sloping outwards, whilst downstream is vertical.
+On a narrow bridge, a cutwater shape can be carried up to the top of the parapet, to provide a pedestrian refuge.
-[[File:Tczew most wiezyczki 2.jpg|thumb|[[Tczew]], Poland, an isolated starkwater against ice, ahead of a bridge pier which is itself asymmetric]]
+[[File:IMG 4123 Providence and Worcester bridge.jpg|thumb|upright=2.5|left|[[Middletown–Portland railroad bridge]], Connecticut: starlings on the bridge piers and also at each end of the [[swing span]] (the fence-like structures around the piers are pile-supported [[bridge fenders]]).]]
-The starling has a sharpened or curved extreme sometimes called the nose. The cutwater may be of concrete or masonry, but is often capped with a steel angle to resist abrasion and focus force at a single point to fracture floating pieces of ice striking the pier. In cold climates the starling is typically sloped at an angle of about 45°&nbsp; so current pushing against part-submerged ice flow tends to lift the solid ice translating horizontal force of the current to a vertical force shearing the ice allowing the icy flows to pass on either side.<ref>{{cite book
+[[File:Baslow_road_bridge_over_river_Derwent_(geograph_3125886).jpg|thumb|Refuges on [[Baslow|Baslow Bridge]], Derbyshire.]]
- | last =Urquhart | first =Leonard Church
+{{clear}}
- | title =Civil Engineering Handbook
- | publisher =McGraw-Hill Book Company
- | edition =4th
- | date =1959
- | location =New York
- | pages =8–75
-}}</ref> A sloped, ice-cutting starling is known as a '''starkwater'''.<ref>{{cite book
- | last1 =Raymond | first1 =William G.
- | last2 =Riggs | first2 =Henry E.
- | last3 =Sadler | first3 =Walter C.
- | title =The Elements of Railroad Engineering
- | publisher =John Wiley & Sons
- | edition =5th
- | date =1937
- | location =New York
- | pages =163
-}}</ref>
-{{-}}
 == See also ==
+* [[Dolphin_(structure)#To_protect_structures|Dolphin (structure)]]
 * [[Breakwater (structure)|Breakwater]]
 * [[Icebreaker]]