Saturday, January 4, 2014

One liners - Transportation Engineering for GATE, PSUs - Part 8

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

  • The aggregates required for one kilometers length of water bound macadam road per meter width and for 10 mm thickness is 12 cubic meter.
  • The camber of shoulders in water bound macadam roads is equal to the cross slope of pavement.
  • The binder normally used in flexible pavement construction is bitumen.
  • In highway construction rolling starts from sides and proceeds to center.
  • For the construction of water bound macadam roads, the correct sequence of operations after spreading coarse aggregates is dry rolling, application of screening, wet rolling and application of filler.
  • For the penetration macadam construction, the bitumen is sprayed after the aggregates are spread and compacted.
  • When bituminous surfacing is done on already existing black top road or over existing cement concrete road, the type of treatment to be given is tack coat.
  • A bituminous primer is a high viscosity cut-back.
  • The suitable surfacing material for a bridge deck slab is mastic asphalt.
  • The thickness of bituminous carpet varies from 20 to 25 mm.
  • Sheet asphalt is a sand-bitumen mix without coarse aggregates.
  • In highway construction on super-elevated curves, the rolling shall proceed from lower edge towards the upper edge.
  • Expansion joints in cement concrete pavements are provided at an interval of 18 m to 21 m.
  • Contraction joints are spaced closer than the expansion joints.
  • Longitudinal joints are provided in cement concrete roads to prevent longitudinal cracking.
  • Warping joints are provided to relieve stresses induced due to warping.
  • A hill road is one which passes through a terrain with a cross slope of 25 to 60%.
  • In hill roads if several alternate alignments are surveyed which fulfill the geometric standards, then the preferred alignment is the one which has resisting length as minimum.
  • The camber is hill roads in case of bituminous surfacing is adopted as 2.5%.
  • The super-elevation to be provided in horizontal curves of radius R in hill roads is V^2/(225R).
  • The minimum design speed for hairpin bends in hill roads is taken as 20 kmph.
  • The drain which is provided parallel to the roadway to intercept and divert the water from hill slopes is known as catch-water drain.
  • The walls which are necessary on the hill side of roadway where earth has to be retained from slipping is known as breast wall.
  • In hill roads the side drains are provided only on the hill side of the roads.
  • Emulsions are used for stabilizing desert sand.
  • Soil lime stabilization is very effective for stabilizing black cotton soils.
  • Soil lime stabilization is quite effective in warm regions.

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