Monday, December 30, 2013

One liners - Transportation Engineering for GATE, PSUs - Part 5

Hello there,
How have you been? Here is another round of one liners for your preparation for the GATE and PSUs examinations.

  • The diagram which shows the approximate path of vehicles and pedestrian involved in accidents is known as collision diagram.
  • With increase in the speed of the traffic stream, the minimum spacing of vehicles increases.
  • Traffic volume is equal to  traffic density * traffic speed.
  • Practical capacity is also known as design capacity.
  • With increase in speed of the traffic stream, the maximum capacity of the lane first increases and then decreases after reaching a maximum value at optimum speed.
  • Equivalent factor of passenger car unit(PCU) for a passenger car as per IRC is 1.0.
  • Scientific planning of transportation system and mass transit facilities in cities should be based on origin and destination studies.
  • The diagram which shows all important physical conditions of an accident location like roadway limits, bridges, trees and all details of roadway conditions is known as condition diagram.
  • When the speed of traffic flow becomes zero, then traffic density attains a maximum value whereas traffic volume becomes zero.
  • On a right angled road intersection with two way traffic, the total number of conflict points is 24.
  • The background of informatory  sign board is yellow.
  • Level crossing is indicated by a warning sign.
  • "Dead Slow" is a regulatory sign.
  • The most efficient traffic signal system is flexible progressive system.
  • The provision of traffic signals at inter-sections reduces right angled collisions but may increase rear end collisions.
  • Stop or red time of a signal is the sum of go and clearance for the cross flow.
  • Clearance time is generally 3 to 5 seconds.
  • The cycle length is normally 40 to 60 seconds for two phase signals.
  • Centre line markings are used in roadways meant for two way traffic.
  • The particular places where pedestrians are to cross the pavement are properly marked by the pavement marking known as crosswalk lines.
  • The entrance and exit curves of a rotary have different radii and different widths of pavement.
  • When two equally important roads cross roughly at right angles, the suitable shape of central island is circular.
  • Beyond 5000 vehicles per hour the rotary may not function efficiently.

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