For Indian practice on straight cement-concrete (rigid) roads, what is the desirable camber (cross fall) range expressed as 1 in n for effective drainage without discomfort?

Introduction / Context:
Camber is the transverse slope provided on road surfaces to rapidly drain rainwater. For rigid pavements (cement concrete), smaller cambers are preferred to limit discomfort and edge uplift while still ensuring water does not pond.

Given Data / Assumptions:

• Straight alignment, cement concrete surfacing.
• Desirable (not minimum or maximum extreme) values appropriate for Indian conditions.

Concept / Approach:
Rigid pavements have smoother, less textured surfaces than bituminous layers and are jointed; they require modest cross fall since concrete is less susceptible to stripping. Typical practice recommends a camber around 0.67% to 0.71%, i.e., 1 in 150 to 1 in 140.

Step-by-Step Solution:

Verification / Alternative check:
Field experience shows this range provides quick surface drainage while maintaining ride quality on rigid pavements.

Why Other Options Are Wrong:
1 in 33–1 in 40 and 1 in 25 are too steep for concrete, suiting bituminous roads under heavy rainfall; 1 in 160–1 in 140 includes a value slightly flatter than typical at the lower end, but the widely cited desirable band is 1 in 150–1 in 140.

Common Pitfalls:
Using very steep cambers on rigid pavements causing uncomfortable cross slope; using too flat a camber leading to water film and skidding risk.

Final Answer:
1 in 150 to 1 in 140