Considerations Wye (rail)

1 considerations

1.1 @ junctions
1.2 turning equipment
1.3 streetcar or tram systems
1.4 disadvantages
1.5 land usage

considerations
at junctions

the use of triangular junctions allows flexibility in routing trains line other line, without need reverse train. reason common across rail networks. slower bi-directional trains may enter wye, letting faster 1 pass, , continue on same direction providing service nearby freight transport or passenger station.

where 1 or more of lines meeting @ junction multi-track, presence of triangular junction introduce number of potential conflicting moves. reason, traffic heavy, junction may incorporate flying junctions on some, or all, or legs of triangle.

for turning equipment

illustration of usage of wye track turning rail vehicle

from time time necessary turn both individual pieces of railroad equipment or whole trains. may because piece of equipment not directionally symmetrical, example in case of steam locomotives and, in parts of world, diesel locomotives, or train needs run particular direction, example has dedicated tail end car such observation car. equipment symmetrical, periodic turning may still necessary in order wear.

there several different techniques can used achieve such turning. railway turntables require least space, can deal single piece of equipment @ time. balloon or turning loops can turn trains of length – total length of loop – in single operation, require far more space wyes. rail wyes can constructed on sites loop not possible, , can turn trains length of stub tracks @ end of wye.

railroad systems in north america , australia have tended have more wyes railroads elsewhere. north american locomotives , cars (such observation cars) more directional found on other continents. in canada , united states, railroad built before other structures, , railway builders had more freedom lay down tracks wished. australia has large amount of open space, , @ many rural railway locations in australia triangles used alternative turntables reasons of space availability , cost saving (both on installation , maintenance).

in europe, although use made of bi-directional tank locomotives , push–pull trains, steam locomotives uni-directional. because of land usage considerations, turntables used turn such locomotives, , terminal stations , locomotive depots equipped. on time, diesel , electric locomotives ordered in europe have been designed bi-directional, symmetrical, , 2 driving cabs. turntables and, existed, rail wyes, have been taken out of use.

streetcar or tram systems

similar considerations apply use of triangular junctions , reversing wyes on streetcar , tram systems, apply mainline rail systems. many, although no means all, streetcar , tram systems use single ended vehicles have doors on 1 side only, , must turned @ each end of route.

however vehicles used on such systems tend have smaller minimum curvature requirements heavy rail equipment. renders use of balloon loop more practical in small amount of space, , street-running vehicles such loop can make use of side streets or street squares. however, although turning loops common way of turning such vehicles, wye tracks used.

disadvantages

a triangle may have situational disadvantage in train operations when space constraints , routing of local geography means taking triangle connects desired destination, locally bypasses main station. in tight city environments, can happen easily, did, example, @ cootamundra west, australia , tecuci, romania, passenger station had built serve trains taking shortcut.

in contrast, engineering of terminus station such woodville railway station, new zealand avoided problem building balloon loop (reversing loop) trains can serve main station in either direction without need reverse. in midline station desired reverse consist or locomotive, double-track , turning wye arrangement far more common.

land usage

a park located within triangular junction

the land within triangle cut off adjacent area (and fenced off) , has marginal value, purposed railways exclusive use — used maintenance depots, storage, or vehicle parking. triangular shape tends unsuited rectangular buildings. on electrified lines substations tend located inside triangles, in part because land cheap, , because provides convenient , flexible sectioning arrangements.