How do Rapid Exit Taxiways improve aircraft movements? I have been reading about Mumbai Airport (CSIA) (IATA: BOM ICAO: VABB). On it they mention:


  The airport has two intersecting runways. Both runways have been
  upgraded to Code F, which means they can accommodate larger aircraft
  like the Airbus A380. Following a presentation in March 2011 by UK’s
  air traffic service provider NATS on how the capacity of the airport
  can be increased, MIAL set a target of 48 aircraft movements an hour
  in an effort to reduce congestion at the airport. Both runways were
  operated simultaneously especially during peak hours to try and attain
  this target.MIAL scrapped simultaneous Cross-runway flight operations
  in mid-2013 after it found that single runway operations were more
  effective for increasing Aircraft movements per hour. Runway 14/32 is
  now used only when the main runway is unavailable due to maintenance
  or other reasons. The construction of new rapid exit taxiways helped
  in increasing flight handling capacity from 32 movements per hour to
  44 in 2012.


Can somebody share what are these rapid exit taxiways and how do they help to increase flight handling capacity ? 

I did see the OSM page and was able to get this -



Maybe that could help in explaining what is being told to us. Have given/shared a more detailed diagram that I could find from OSM. 



Also it would be nice if a sketch/diagram of how these rapid taxiways are laid on CSIA or failing that a diagram of any airport having similar/more/less number of rapid exit taxiways would be good too in order to understand how they work.
See this related question.

Rapid exit taxiways (or high speed exits) enable aircraft to leave the runway at speeds up to 50 or 60 kts depending on the runway and aircraft type (50 kts even in wet conditions).  

They have a long, constant radius rather than a 90 degree turn.

You might find this FAA presentation useful.


Source: airlinepilots.com forum.

The purpose is to enable a landing aircraft to vacate the runway more quickly without having to slow down to "normal" taxi speeds.  A large aircraft like a 777 might need to slow to 10 or 15 knots to take a right angle turn.  This would mean spending longer on the runway slowing down to that speed.  

Since the aircraft next on the approach cannot land until the runway is clear, this enables closer spacing of landing aircraft.

Aircraft type, airport restrictions, operator standard procedures and weather can all impact what "high speed" means but it is always faster than the 90 degree turn.