page_title: Double junction
section_title: Diamond
hierarchical_section_title: Double junction / At grade / Diamond
caption_attribution_description: English: The diamond Crossing at Nagpur is a unique marvel of engineering that exists in very few places in the World. Nagpur is where trunk railway lines running from Kolkata in the Eastern end of India to Mumbai in the Western end, and the one from Delhi in the Northern end to Chennai and other places in the southern end cross. Nagpur in fact is the geographical Centre of the Indian subcontinent. The double lines crossing from the North to the South and those from East to West form a square shape and is called the diamond crossing. It is crucial and is used widely. The people who operate the lines are ever vigilant. Narayan Ramdas Iyer at the Diamond Crossing, Nagpur.
context_page_description: A double junction is a railway junction where a double track railway splits into two double track lines. Usually, one line is the main line and carries traffic through the junction at normal speed, while the other track is a branch line that carries traffic through the junction at reduced speed.
  A number of configurations are possible.
context_section_description: The simplest and oldest arrangement consists of two turnouts and a fixed Diamond crossing. Because the diamond needs to be relatively coarse, say 1 in 8, the curve radius is necessarily small, leading to a speed of perhaps 25 km/h (16 mph). This type of junction is common on street-running tramways, where speeds are quite low and junction must fit into the available road space. Because the points are close together, the entire junction can be controlled by the mechanical point rodding of a single signal box.
  Signal passed at danger (SPAD) protection — A train from R to P with 12 points reverse is protected from a train from P doing a SPAD by 11 points also lying reverse. A train from P to Q is NOT protected from a train from R doing a SPAD.
caption: Diamond crossings in Nagpur, India
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