The use of PIRs reflects the NZTA's emphasis on continuous improvement. The NZTA and its funding partners use PIRs to identify lessons learned that can then be applied to future projects. A PIR is generally conducted two or more years – and often five or more years – after a project is completed. This allows for a more meaningful assessment of how well a project has achieved its expected outcomes.
Projects selected for a PIR cover a range of factors, including cost, scope and regional spread. In addition, projects that went smoothly or encountered unforeseen problems are often selected for PIRs, as both offer valuable learning opportunities.
In 2012, as part of a wider initiative to improve the agency's measurement of project outcomes, the NZTA reviewed the methodology used for PIRs conducted from 2008-11. This work questioned the value of conducting a pre- and post-completion comparison of a project's benefit cost ratio, as the initial ratio is only an estimate based on available knowledge at the time; it is not a precise prediction of outcomes. However the majority of PIRs still indicate that the investments were worthwhile.
While the NZTA found that pre- and post-completion comparison of benefit cost ratios provided some feedback on a project, this feedback was limited and it has not allowed for indepth understanding of any differences between expected and actual project benefits.
To address this limitation, enhance the learning opportunities and increase the focus on benefits realisation, the NZTA will introduce a revised PIR methodology in late 2012. From that point, PIRs will no longer attempt to recalculate the benefit cost ratio. Instead, PIRs will focus on:
- assessing how well a project has delivered the expected benefits
- explaining variation between actual and expected benefits and costs
- identifying lessons learned that can be used to improve future projects and NZTA's processes and procedures.
PIRs by year
- Post implementation reviews completed in 2011/12 (PDF, 11 pages, 842 KB)
- Northern Busway Review summary May 2012 (PDF, 8 pages, 440 KB)
- Northern Busway Review report May 2012 (PDF, 32 pages, 796 KB)
- Northern Busway Review annexes May 2012 (50 pages, 1.8 MB)
- Victoria Park Tunnel Report (PDF, 19 pages, 1.2 MB)
- The implications of road investment - November 2012
- Post implementation reviews completed in 2010/11 (PDF, 24 pages, 1.8 MB)
- Post implementation reviews completed in 2009/10 (PDF, 35 pages, 1.7 MB)
- Post implementation reviews completed in 2008/09 (PDF, 21 pages, 119 KB)