Grand union

This article is about a type of tram/railway junction. For the canal, see Grand Union Canal, for the supermarket, see Grand Union (stores), for the rail operator, see Grand Union Railway, for the flag, see Grand Union Flag.

A grand union is a rail track junction where four two-track railway lines meet, often at a street intersection or crossroads. A total of sixteen railroad switches (sets of points) allow a streetcar 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 location.

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 is Balaclava Junction in Melbourne, Australia. New Zealand formerly had two in Auckland, at Queen Street's intersections with Customs Street and Wellesley Street.

The most extensive street railway system in North America is the Toronto streetcar system of the Toronto Transit Commission in Toronto, Ontario, Canada which has several grand unions. Historically, the system operated by Montreal Tramways Company (Montreal street railway system) had a number of grand unions.

References