• For a single lane traffic the desirable lane width is – 3.75 m
  • Acoording to recommendation of Nagpur conference the width formation of an ideal national highway in hard rock cutting is – 7.9 m
  • According to highway research board, soils are classified into – 7 types
  • Height Range of footpaths -  15 cm to 20 cm
  • Footpaths are particularly provided in the case of urban road
  • Right of way for National highway for plain terrain is – 45 m
  • IRC recommendation for maximum width of a vehicle is – 2.44 m
  • Based on location and function Nagpur road plan has classified the roads in India in  - 5 parts
  • The width of carriageway for multi Lane payment as recommended by the Indian Road Congress is – 3.5 m per lane
  • Border roads Organisation for hilly region was formed in 1960
  • The minimum width of the NH should be 5.7 m
  • As per IRC recommendation the roadway width for single Lane NH or SH in mountainous or steep terrain is – 6.25 m
  • A pavement is classified as flexible or rigid based on its base
  • As per IRC the super elevation to be provided in horizontal curves of radius R is given by – V2/127R
  • For comfortable travel on highway the centrifugal ratio should not exceed 0.25
  • The recommendation value of camber provided on cement concrete Road are 1.7 to 2.0

 

Types of Roads camber
Concrete Road 1 IN 60
Bituminous Road 1 IN 50
W.B.M or Gravel 1 IN 40
Pavings 1 IN 60
  • Grade compensation on horizontal curve on a highway is not necessary when gradient is flatter than 4% percent
  • The design value of stopping sight distance for a two Lane two way traffic would be equal to stopping sight distance
  • Excessive camber on pavement may cause deterioration of a Centre portion, erosion of the berms, slip of the speedy vehicles
  • Rolling resistance of a wheel depends upon vehicles loads and ground condition.
  • The shape of the camber best suited for cement concrete pavement is straight line
  • The length of the road ahead of the vehicles which is visible to the driver is called as sight distance
  • when the centrifugal ratio attains a value equal to the coefficient of lateral friction there is a danger of = lateral skidding
  • The coefficient of lateral friction for aquarium super elevation is taken as zero (0)
  • IRC recommendation for ruling design speed on a national highway in plain terrain is = 100 km/h

 

Types of roads Plains roads Mountain roads
General Minimum General Minimum
National and State Highways 100 80 50 40
Main District Roads 80 65 40 30
Other District Roads 65 50 30 25
Rural Roads 50 40 25 20
  • The desirable length of overturning Zone for a Highway at per Indian Road Congress recommendation is equal to five times overtaking sight distance
  • Full amount of extra width of pavement from the curve is provided at beginning of the circular curve
  • The length of a transition curve is proportional to v2/R
  • A flyover segregates traffic with respect to  grade
  • Grade compensation is not necessary for gradients less than 4%
  • To ensure that bullock carts may not overturn on curve , the maximum value of Superelevation is 1 IN 15
  • The ideal shape of transition curve on road is Cubic parabola
  • The ruling gradient for plain and rolling Terrain is 3.3%
  • The unit of rate of change of centrifugal acceleration of a transition curve is metre per second cube
  • One degree of curve is equivalent to 1750/R
  • Design of cement concrete pavement for corner loading IRC recommendation the use of Pickard’s formula
  • Enoscope is used to determine spot speed
  • For the preparation of Highway longitudinal section are required and cross sections are also required
  • The capacity of a single length road is inversely proportional to the average Centre to Centre spacing of the vehicles
  • Concrete payment is provided if daily traffic load per length exceeds 1000 tons
  • Alignment of road is finally recorded on the basis of field survey
  • location of Counter gradient for a highway is best set out from the the saddle down the hill
  • Average illumination on important Roads as per I.S recommendation is 70 lux
  • Annual  average daily traffic is obtained by determining average daily traffic volume recorded for 365 days
  • The traffic volume is equal to traffic density * traffic speed
  • Webster’s Method is used for determining optimum signal cycle
  • In case of multi-lane Road overtaking is generally permitted from both right and left sides
  • The minimum length of overtaking zone be three times the safe overtaking distance
  • Traffic conflicts that may occur in a Rotary intersection are merging and diverging
  • With the increase in speed of the traffic stream the minimum spacing of vehicles increase
  • The distance travelled by a moving vehicles during perception and braker action time is known as Lag distance
  • The most suitable traffic signal system for mixed traffic condition is flexible progressive
  • In a parking area the maximum number of vehicles can be parked with 45 angle parking
  • The color of the upper part of kilometer stone on road side in case of a stone Highway is green
  • The greatest test on bitumen is used for determining its grade
  • The ductility value of bitumen is less than that of tar
  • As per IRC for bitumen bound macadam maximum aggregate impact value in percent will be 30%
  • The specific gravity of bitumen  = 1.09

 

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