Choice of rigid (concrete) pavement by traffic loading A cement concrete pavement is generally provided when the commercial daily traffic per lane exceeds approximately:

Difficulty: Medium

Correct Answer: 1250 tonnes

Explanation:


Introduction / Context:
Selection of rigid versus flexible pavement is influenced by traffic loading, subgrade support, climate, and life-cycle cost. Higher daily loads favor rigid pavements due to better load distribution and reduced rutting.



Given Data / Assumptions:

  • Commercial traffic expressed as total tonnes per lane per day.
  • Normal subgrade and climate, without unusual constraints.


Concept / Approach:
Empirical thresholds guide preliminary decisions. Above a certain daily tonnage, rigid pavements often provide superior performance and economics through longer life and lower maintenance under heavy loads.



Step-by-Step Solution:

Compare daily tonnage against common selection bands.Adopt rigid pavement beyond ≈ 1200–1300 tonnes/lane/day.Hence select 1250 tonnes as the representative threshold among options.


Verification / Alternative check:
Detailed design with cumulative ESALs and fatigue models can refine the choice, but preliminary screening often uses such tonnage benchmarks.



Why Other Options Are Wrong:
500–1000 tonnes may still be economical with strong flexible structures; 1300 is plausible but 1250 matches a typical rule-of-thumb breakpoint.



Common Pitfalls:
Ignoring axle-load spectra and growth rate; not considering climate-induced cracking or base erosion.



Final Answer:
1250 tonnes

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