Picking up Road Surface & Re-sectioning

The first operation in resurfacing a macadam road is picking up the old road surface. This is a strenuous operation and is frequently neglected. To ensure quality, it is highly recommended to use pavement breakers powered by a compressor unit rather than manual labor alone.

Following the pickup, the road must be sectioned to the proper camber. This should primarily utilize the old picked-up metal; however, if the volume is insufficient, new material may be added. Precision sectioning requires the mandatory use of proper wooden templets.

Critical Engineering Fact: After sectioning with old (and potentially some new) metal, the road must be rolled to its proper section before the final layer of new metal is added. The integrity of the final road profile depends entirely on this initial rolling phase.

Camber

Traditional PWD circulars specify a camber of 1 in 36. However, observations show that road crowns flatten over time due to traffic, often resulting in a "saucer-shaped" surface that traps water.

To counteract this, it is recommended that the initial camber be set at 1 in 24 or 1 in 20. This ensures that even after natural flattening, a functional camber of approximately 1 in 30 is maintained. Wooden templates should be prepared specifically to the 1 in 20 ratio to prioritize effective drainage.

Consolidation

Consolidation is the single most important factor determining the success or failure of a macadam road. Success depends on the mechanical interlocking of the metal stones, which is achieved through precise rolling techniques.

"The paper by Mr. Mckelvie and Raghavachari (Indian Road Congress, 1946) remains the definitive authority on macadam road construction. Its principles must be put into actual practice by every road engineer."

Requirement	Specification
Minimum Roller Weight	12 Tonnes (Preferably 15 Tonnes for hard metal)
Minimum Roller Passes	90 passes over any given spot
Dry Consolidation	Roll to refusal (no movement visible under roller)
Field Test	Loaded water cart must leave no impression/movement

The Dry Rolling Phase: Not a single drop of water should be applied until dry consolidation has reached the point of refusal. Sprinkling water too early—as if mixing concrete—turns the layer into "mud concrete." Such a surface cannot withstand modern pneumatic tire traffic and will rip up rapidly under heavy loads.

Note: Sheep foot rollers are specifically useful for consolidating embankments formed of silty or murum materials, though highly clayey soils (like Black Cotton Soil) must be avoided in bank work.