When a hill road section fails, the visible damage is in the pavement or the slope face. The cause is almost always water that was never given a controlled route.
Rebuilding the pavement without correcting the drainage returns the same failure within two or three seasons — at full cost each time.
Diagnose before specifying
On a recent rehabilitation contract, seven failure zones were assessed individually. Four turned out to need drainage correction rather than structural retention. Building retaining structures at all seven would have cost significantly more and addressed the mechanism at only three.
Build drainage first
Catch drains, cascades and cross-drainage should be complete before the wet season the road has to survive — which means they are built early in the programme, not as finishing works.
Bio-engineering on completed slope faces then sustains surface stability once construction leaves site.
- Assess the failure mechanism before selecting a remedy
- Complete drainage ahead of the season it must handle
- Size cross-drainage against updated rainfall data, not original design assumptions
- Plan for maintenance access to every drainage structure