1. Pavement Rehabilitation
Drainage Renewal or
Pavement Rehabilitation
Which should come first?
William Gray, CPEng
Technical Principal (Pavements)
Elke Beca, MTech Pav, BE
Strategic Asset Management Engineer

2. Introduction
As early as 1820, John McAdam noted that regardless of the thickness of the pavement structure, many roads in Great Britain deteriorated rapidly when the subgrade was saturated

3. NZTA funded research
Analysis tool and associated methodology to plan pavement drainage interventions.
The Opus project team acknowledge the support of NZTA, in particular Gordon Hart and Roger Bailey; Luca De Marco (past NZTA project manager); the project Steering Group and Peer Reviewer Dr Ian Greenwood.

4. Drained or undrained The Repeat Load Triaxial Test (RLT):
pore pressure and strain rate changes in undrained state affects basecourse performance

5. Pavement and land drainage
Our project has been focussed on pavement drainage assets

6. Pavement Drainage Initiatives
Prevent moisture entering pavement
Waterproof surface and shoulder
Longitudinal drains (lined/unlined channels and side drains)
Adequate cross slope and longitudinal grades (crossfall and gradient)
Manage groundwater effects
Subsoils
Pavement materials - moisture sensitivity
Control fines from production, construction and ageing
Minimise moisture in pavement structure
Surface is maintained separately and not typically considered under ‘drainage’
Only factors that can be influenced outside of pavement renewal is longitudinal drains

7. Research Report 555
Optimising Drainage Maintenance for Pavement Performance.
(J. Patrick, H. Arampamoorthy, G. Arnold)
Exponential relationship between saturation and rate of rut development in granular basecourse
Equilibrium saturation ~60%
Finite element models show once basecourse infiltrated, can take weeks for water content to return to equilibrium.
Impact of moisture in pavements under loading
How long does water stay in a pavement
Method for identifying drainage deficient areas in the field

8. Research Report 555 - Scorecard

9. Research Report 555 Recommendations
Drainage risk score included in RAMM
RAMM Drainage condition rating carried out for high risk sections
Rut rates monitored as standard process for subsoil deficiency or blockage.

10. TRB Research Paper LTPP data Rut progression dependant upon
The Relationship between Traffic Loading and Environmental Factors to Low Volume Road Deterioration. (Henning, Alabaster, Arnold & Liu (93rd TRB Conf.))
LTPP data
Rut progression dependant upon
Moisture sensitivity
Drainage adequacy
ESA
docs.trb.org/prp/ pdf 

11. Current Research
Objective – to develop analysis tool for business case planning
Forecast renewal need for drainage and benefits of intervention
Investing more in drainage needs and programming drainage works well ahead of resurfacing/renewals will prolong the life of the existing pavement

12. Activities and Collaboration
Develop robust short term plan (FWP – 5yr)
Understand long term funding needs
Opus Surface Model
Empirical – Stochastic – pavement condition data
Geosolve Subsurface Model
Mechanistic – FWD – pavement performance data
Pilot Areas: SH2 Napier to Wairoa, SH 1 Northland and the Western Bay of Plenty network

13. Day One…………