Quarrying & Mining Magazine

The road to better quality basecourse

This article first appeared in Q&M‘s February-March issue.

John Donbavand, the NZTA National Pavements manager, made a presentation at the NZTA-NZIHT conference in Dunedin late last year. ALAN TITCHALL was there.

With his responsibility in maintaining and developing pavements standards, specs and guidelines for state highway pavements, John Donbavand raised a number of issues relative to the future use of aggregates and the implementation of the recommendations from the working group on the Quality Right Project.
Although NZTA acknowledged that improvements could be made to all parts of its capital projects, its senior management decided to focus on pavements since it is the big ticket item, and some of the areas of quality pavement change will inevitably have a positive impact on other areas.
The working party, which includes representation from CCNZ, ACENZ and NZTA, had met twice by the end of 2016 and a work plan was developed from the first meeting. This plan stretched across a wide range of activities that included reviewing procurement, skill sets, inspection and testing, quality assurance and approval processes.
“We know [in the past] there has been a focus on short-term performance from our suppliers rather than the agency’s long-term goals,” he concedes.
“To put it nicely – this has led to attenuated pavement solutions and, to put it not so nicely – skinny pavements.
“We [NZTA] are now going to prescribe the pavement options that include layer thickness, material properties, and material performance.
“You might say hang on – that’s where the innovation is, but we haven’t had any innovation for 25 years in these areas.
“We are suggesting – let’s just stipulate and, for the contractor, this is a great thing as then the contractor will know what they are tendering on. They know what the thickness is.
“And it leaves room for the supplier to focus their ‘innovation’ on how they put the material together, where they source it, and how they construct it.”
Resource capability
John says that when it comes to supervision, the Transport Agency needs the right people on the project site.
“The agency needs to invest in a good supervision process control engine. We need to make sure the right people are on site who are driving the right behaviours, and not just a graduate engineer – no disrespect to them and they are our future, but they may not be the people that are likely to ensure we get the best quality. They should be there learning.
“So we will require the people who are providing the on-site supervision to  be named in the [future] tender documents and their experience and a relevant track record will be assessed as part of the tender evaluation.
“Then it comes to us in terms of our monitoring.
“We are making training available in general pavement engineering, as and when required, to make sure us  as project managers are knowledgeable enough to know when something is not quite right and should be challenged.”
The full set of recommendations from the Quality Right Working Group included:

  • Include quality requirements in the prequalification system;
  • Regular meetings to discuss quality between the contractor/consultant/client;
  • Client to stipulate time frames for receiving test data;
  • Greater prescriptiveness for pavement design;
  • Improved principal requirements;
  • Client/consultant/contractor to agree the critical phases of the pavement construction;
  • Critical phases to form hold points which must be signed off by the client before progressing;
  • Increased observation (Construction Monitoring Service level 5 to be considered);
  • Ensuring all consultants involved with verification, certification and approval have appropriate skill levels;
  • All non-conformances to be held in a central register;
  • Ensure we are knowledgable clients;
  • Provide a central hub for all quality data – this hub to be accessible to contractor/consultant and client working on the capital project.

The agency acknowledges that the short terms costs are going to be higher, but these will be more than offset by the long-term savings, says John.
“And there are other benefits such as improved safety and a reduction in public disruption; this is important for us as a customer orientated organisation.
“And the one for me is improved employee morale. Let’s face it – the last thing anybody wants is for our contracting staff to go home and say ‘the project is crap, but then you get what you pay for’.
“This is all a big change to get that quality and I don’t know if people appreciate how big.”
Quarry accreditation and evaluation process
In addition to this project the Transport Agency has been reviewing the quality of the basecourse material coming from quarries through historic test data on production properties on the Specification for Basecourse Aggregate, NZTA M/4.
Test information from over 40 quarries was examined and it was found that the level of compliance was very low, says John.
“It was obvious from this evaluation that changes were required.
“Recommendations for improvement included: Changes to the sampling regime; review of the grading envelopes; and development of a QA system and associated ‘process  control chart’ software.”
With regard to the process control chart the NZTA ‘stole’ ideas from CCNZ in the way the association monitors asphalt using the asphalt plant accreditation scheme, he adds.
“We have established a similar system for quarries and the Aggregates and Quarry Association (AQA) has agreed to assist us monitor the data.
“The AQA have been assisting us throughout the process and will be pivotal in the implementation of the quality assurance scheme.”

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