22 YEARS EXPERIENCE
Chaminda Ekanayake
Principal Engineer — Roads & Transport
§ Service 013 · Pavement & Surfacing Design
Pavement & Surfacing Design
Full pavement and surfacing design cycle to NZTA M/4, M/10, M/6, M/23 and Austroads standards — from FWD testing and field investigation through to pavement design, ITP/RQP and post-construction reporting. TTAP is an appointed member of the NZTA IDM Pavement & Surfacing Design Services panel (Manawatū–Whanganui, Taranaki, West Waikato).
Who it's for
- NZTA Waka Kotahi
- Local councils
- Maintenance contractors & alliances
The problem we solve
A pavement or surfacing treatment specified without the evidence behind it — the deflection data, the materials testing, the rutting and roughness history — either fails early or over-builds and wastes budget. On the state highway network and council roads alike, treatment selection has to be defensible against the design standards and auditable after construction.
We run the full design cycle on the data: FWD deflection testing and field investigation, lab characterisation, structural design to NZTA and Austroads methods, and the ITP/RQP and post-construction records that make the work audit-defensible. TTAP is an appointed member of the NZTA IDM Pavement & Surfacing Design Services panel.
What's included
- FWD Testing
- Field Investigation
- Lab Testing
- Geometric Design
- Pavement Design
- ITP / RQP
- Post-Construction Reporting
What you get
- Falling Weight Deflectometer (FWD) survey and back-analysis
- Field investigation — test pits, sampling, condition and drainage review
- Pavement design report (rehabilitation or new) to NZTA / Austroads methods
- Surfacing design and treatment selection — chip seal or asphalt
- Inspection & Test Plan (ITP) and Record of Quality Performance (RQP)
- Post-construction / as-built reporting and design certification
How we work
- 01
Investigation
FWD deflection testing, test pits, sampling, and a condition and drainage review establish what the existing pavement is actually doing.
- 02
Analysis & characterisation
Deflection back-analysis and lab testing characterise subgrade strength and layer condition — the inputs the design stands on.
- 03
Design
Structural pavement design (rehabilitation or new) and surfacing selection to NZTA M/4, M/10 and Austroads methods, with whole-of-life treatment options.
- 04
ITP / RQP
We set the Inspection & Test Plan and Record of Quality Performance so construction quality is specified and captured, not assumed.
- 05
Post-construction
As-built and post-construction reporting closes the loop, with design certification the RCA can rely on.
Standards
- NZTA M/4 (basecourse aggregate)
- NZTA M/10 (dense graded & SMA asphalt)
- NZTA M/6 & M/23 (sealing chip & bitumen)
- Austroads pavement design guides
- NZTA Infrastructure Design Manual (IDM)
Tools
- Falling Weight Deflectometer (FWD)
- Deflection back-analysis
- CIRCLY / mechanistic design
- Whole-of-life treatment comparison
Relevant projects
Who leads this work
Frequently asked
Do you cover both pavement and surfacing, or just one?
Both — the structural pavement design through to the surfacing treatment (chip seal or asphalt) and the seal or AC design that goes with it. Treating them together is what produces a whole-of-life answer, rather than a surfacing that outlives or under-lives the pavement beneath it.
Can you work on the NZTA state highway network?
Yes. TTAP is an appointed member of the NZTA IDM Pavement & Surfacing Design Services panel for Manawatū–Whanganui, Taranaki and West Waikato, so we deliver pavement and surfacing design directly under that panel as well as for councils.
What investigation do you need before designing a rehabilitation?
Typically FWD deflection testing plus test pits and sampling, alongside the condition, rutting, roughness and drainage history. The deflection back-analysis and lab results are what let us design to the evidence rather than to assumption.
How do you make the design audit-defensible?
The ITP and RQP specify and record construction quality, and the post-construction report and design certification close the loop — leaving a design and a record an RCA or auditor can follow from investigation through to as-built.