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Q: The longitudinal coefficient of friction on highway for calculation of stopping distance in geometrical design is :
  • A. 0.3 to 0.34
  • B. 0.35 to 0.4
  • C. 0.25 to 0.29
  • D. 0.5
Correct Answer: Option B - • The frictional resistance developed between road and tyres or the skid resistance depends on the type and condition of the road surface and the tyres. The braking distance increases with decrease in skid resistance. • IRC specified a design friction coefficient of 0.35 to 0.4 depending upon the speed to be used for finding the braking distance in the calculation of stopping sight distance. • Coefficient of lateral friction as 0.15 is useful in horizontal curve design.
B. • The frictional resistance developed between road and tyres or the skid resistance depends on the type and condition of the road surface and the tyres. The braking distance increases with decrease in skid resistance. • IRC specified a design friction coefficient of 0.35 to 0.4 depending upon the speed to be used for finding the braking distance in the calculation of stopping sight distance. • Coefficient of lateral friction as 0.15 is useful in horizontal curve design.

Explanations:

• The frictional resistance developed between road and tyres or the skid resistance depends on the type and condition of the road surface and the tyres. The braking distance increases with decrease in skid resistance. • IRC specified a design friction coefficient of 0.35 to 0.4 depending upon the speed to be used for finding the braking distance in the calculation of stopping sight distance. • Coefficient of lateral friction as 0.15 is useful in horizontal curve design.