- Grand union
:"This article is about a type of tram/railway junction. For the canal, see
Grand Union Canal , for the supermarket, seeGrand Union (stores) , for the rail operator, seeGrand Union Railway , for the flag, seeGrand Union Flag ."A grand union is a
rail track junction where four two-trackrailway lines meet, often at astreet intersection orcrossroads . A total of sixteenrailroad switch es (sets of points) allow astreetcar coming from any direction to take any of the three other directions.Complexity
These types of complex junction are expensive to build and expensive to maintain. Special parts, sometimes made of
manganese steel, are needed for each location where one rail crossed another (a "frog"), and these parts often needed to be custom-made and fitted for each single locationFact|date=July 2008.A full grand union junction consists of eighty-eight frogs (where one rail crosses another rail) and thirty-two point blades. A tram or train crossing the junction will encounter between four and eighteen frogs within the space of the junction.
Examples
The only surviving grand union in the
Southern Hemisphere isBalaclava Junction in Melbourne,Australia .New Zealand formerly had two inAuckland , at Queen Street's intersections with Customs Street and Wellesley Street. [Graham Stewart, "The End of the Penny Section: When Trams Ruled the Streets of New Zealand", rev ed. (Wellington: Grantham House, 1993), p. 149.]The most extensive street railway system in
North America is theToronto streetcar system of theToronto Transit Commission inToronto ,Ontario ,Canada which has several grand unions. Historically, the system operated byMontreal Tramways Company (Montreal street railway system ) had a number of grand unions [ [http://www.mccord-museum.qc.ca/scripts/large.php?accessnumber=II-102021&Lang=1&imageID=143196 Musée McCord Museum - Tramway crossing under construction, Ste. Catherine and St. Lawrence St., Montreal, QC, 1893 ] ] .Fact|date=April 2007References
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