Concept
Double-track railway
Related concepts (4)
Rapid transit
Rapid transit or mass rapid transit (MRT), also known as heavy rail or metro, is a type of high-capacity public transport that is generally built in urban areas. A rapid transit system that primarily or traditionally runs below the surface may be called a subway, tube, or underground. Unlike buses or trams, rapid transit systems are railways, usually electric, that operate on an exclusive right-of-way, which cannot be accessed by pedestrians or other vehicles. They are often grade-separated in tunnels or on elevated railways.
Melbourne
Melbourne (ˈmɛlbərn ; Boonwurrung/Woiwurrung: Narrm or Naarm) is the capital of the Australian state of Victoria, and the second-most populous city in Australia (although the most populous in its contiguous urban area). Its name generally refers to a metropolitan area known as Greater Melbourne, comprising an urban agglomeration of 31 local municipalities, although the name is also used specifically for the local municipality of City of Melbourne based around its central business area.
Loading gauge
A loading gauge is a diagram or physical structure that defines the maximum height and width dimensions in railway vehicles and their loads. Their purpose is to ensure that rail vehicles can pass safely through tunnels and under bridges, and keep clear of platforms, trackside buildings and structures. Classification systems vary between different countries, and gauges may vary across a network, even if the track gauge is uniform.
Tunnel
A tunnel is an underground passageway, dug through surrounding soil, earth or rock, and enclosed except for the entrance and exit, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube construction techniques rather than traditional tunnel boring methods. A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. The central portions of a rapid transit network are usually in the tunnel.