Highway Engineering (21-40)

21.As per IRC recommendations, the maximum limit of super elevation for mi;;ed

traffic in plain terrain is 1 in 15

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22.For the design of superelevation for mixed traffic conditions, the speed is reduced by 25%

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23.On a horizontal curve if the pavement is kept horizontal across the alignment, then the pressure on the outer wheels will be more than the pressure on inner

wheels

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24.The equilibrium superelevation required to counteract the centrifugal force fully is given by

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25.For a constant value of coefficient of lateral friction, the value of required.

super-elevation increases with increase in speed and with decrease in

radius of curve

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26.To calculate the minimum value of ruling radius of horizontal curves in plains, the design speed is given by 16kmph

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27.The absolute minimum radius of curve for safe operation for a speed of 110 kmph is 440 m

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28.The attainment of superelevation by rotation of pavement about the inner edge of the pavement avoids the drainage problem in flat terrain

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29.Psychological extra widening depends on the speed of vehicle

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30.In case of hill roads, the extra widening is generally provided fully on the inner side of the curve

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31.The mechanical extra widening required for 10.5 m wide pavement on a horizontal curve of radius R metre is given by

where l is the length of wheel base of vehicle in metres

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32.The transition curve used in the horizontal alignment of highways as per IRC

recommendations is spiral

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33.For design, that length of transition curve should be taken which is

higher of based on allowable rate of change of centrifugal acceleration

higher of based on rate of change of super elevation

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34.The maximum design gradient for vertical profile of a road is ruling gradient

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35.The percentage compensation in gradient for ruling gradient of 4% and horizontal curve of radius 760 m is no compensation

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36.If ruling gradient is I in 20 and there is also a horizontal curve of radius 76 m,

then the compensated grade should be 4%

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37.The camber of road should be approximately equal to half the longitudinal gradient

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38.Which of the following shapes is preferred in a valley curve ?

cubic parabola

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39.The value of ruling gradient in plains as per IRC recommendation is

1 in 30

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40.In case of summit curves, the deviation angle will be maximum when

an ascending gradient meets with a descending gradient