Bridge Structure Glossary

Bridge Structure Glossary

To help understand the terms used in civil engineering to describe various structures used in bridge construction, this glossary has been created. As of Feb 8, 2020, this is the first version of it with terms derived from the article Canadian Railway and Marine World - 1914-11 - Extensive Improvements on the Dominion Atlantic Railway, P490

Aboiteau

A type of dyke with gravity and pressure controlled automatic drainage gates or check valves that allows water to drain to the sea but keeps seawater from flowing back under the dyke. While maintenance is needed, no attention is required for each change of the tide. See for example https://en.wikipedia.org/wiki/Aboiteau#/media/File:Dam_slit_2D-en.svg

Concrete Rail Top Culvert

A small concrete culvert with the rails and ballast laid directly on top - would look like a small concrete bridge. It may or may not have a paved bottom. This is not a common usage. Most culverts are much lower than the railway bed.

D.T. Span

is "deck truss span"

D.P.G. Span

A "deck plate girder" span. The deck is high, at the top of the girders. https://en.wikipedia.org/wiki/Plate_girder_bridge#/media/File:PlateGirderUnderTracks.jpg

Deck Truss Bridge

A truss bridge with the roadway/railway on top of the trusses. This allows multiple cross bracing under the roadway/railway which can then be more compact for the same strength as other types. The downside is more clearance above the water or whatever passes underneath is needed. An example: https://en.wikipedia.org/wiki/Truss_bridge#/media/File:ErieCanalRRBridge04_1A.jpg
The second Bear River bridge is shown at: http://dardpi.ca/wiki/index.php?title=File:Train_No._98_on_Bear_River_Bridge_3.jpg At the far end is a plate deck girder span, then a deck truss span that swings (swing span), then three 156' truss spans, then two more deck girder spans.

H.D.P.G. Span

A "half deck plate girder" span. The sides are plate girders with the deck about halfway between the top and bottom of the girders. See the part of the RR bridge (where the train is) shown at http://dardpi.ca/wiki/index.php?title=File:Avon_River_Bridge_c.jpg Notice the rails are hidden behind the side of the girders, but at not all the way down to the bottom of the girders.

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H.T.G. Span

A (possibly?) half truss girder - a truss bridge with the deck about halfway between the top and bottom of the truss. The article cites the Gaspereau Bridge, but the spans there in 2010 were two through trusses and two half deck plate girder spans. Perhaps the half deck spans were done later than 1911. An example on the HSW is http://hswdpi.ca/wiki/index.php?title=File:Tusket_River_Bridge_4.JPG

Lattice Girder

A type of truss, usually constructed of many small members close together. The first Windsor bridge was a lattice bridge. http://dardpi.ca/wiki/index.php?title=File:201580207.jpg They are distinguished from other truss bridges by the number of small members and the overlap between them. Other trusses are more open, such as the highway adjacent.

Lattice Member

A beam or column made up of smaller pieces in a lattice. These are often seen as part of a larger bridge. An example is the parts of the Bridgetown bridge: http://dardpi.ca/wiki/index.php?title=File:Bridgetown_3_%281280x853%29.jpg

Lift Span

A movable bridge that is raised to allow ships to pass beneath.

P.G.D.S. Span

A "plate girder deck span"

Surface cattle guard

A cattle guard at a crossing (possibly?) like this: https://en.wikipedia.org/wiki/Cattle_grid#/media/File:Rail_cattle_guard.jpg with no deep pit beneath it. While a pit cattle guard has more space below the rails, as at https://steelcattleguards.com/collections/all/products/blm-cattle-guard-grid-hs-20

Swing Span

A movable bridge that rotates about a vertical axis to allow ships to pass to one side or the other.

T.T. span

A "through truss" span, such as at Bridgetown http://dardpi.ca/wiki/index.php?title=File:Bridgetown_3_%281280x853%29.jpg

Through Girder Span

As seen at http://dardpi.ca/wiki/index.php?title=File:DAR0029b.jpg and at http://dardpi.ca/wiki/index.php?title=File:CPR8131d.jpg (same bridge) Note the rails are at the bottom of the girders.

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Truss span

A truss bridge between two piers or abutments. So a multi-span bridge might have say, two abutments, one each end, and three piers (free-standing towers), with five "spans" where a span is the distance between a pair of piers or between a pier and an abutment.