As we learn more about the how our road network holds up to possible unexpected disruptions and other unexpected disruptions, we better understand where we need to invest – both to increase its resilience and to provide better indicators and predictors of potential disruption.

This page provides a range of tools and tips in a business case context to help develop interventions and agreed responses to improve the resilience of networks. It also provides nationally consistent information on the risks of high impact low frequency events (such as earthquakes).

These tools help us and our suppliers identify and evaluate resilience risks and issues, and their likely impacts as well as prioritise potential responses.

Resilience in the strategic business case

This note [PDF, 434 KB] gives examples and insights using a resilience lens on the planning process and can be used by anyone developing a strategic case to incorporate resilience into their assessments.

Hazard exposure scan

The maps section(external link) of our site provides an assessment of key natural hazards focussing on low frequency, high impact events (such as earthquakes) that may impact the availability of the network, and includes an assessment of the extent and duration of the outage.

Lessons from Kaikōura

Following our hazard exposure scan process, the 2016 Kaikōura earthquake hit severely disrupting the availability of State Highway 1. We used this event to test the accuracy of our assessment, and to pick up any lessons learnt. Overall, this process found that our hazard exposure scan was highly consistent with what happened in a real life event. The report and lessons learnt are available [PDF, 4 MB].

Identify detour routes

When a section of our roading network becomes unexpectedly out of action we need suitable detour routes to ensure people can finish their journeys.

We have built interactive detour maps(external link) that, with a handful of clicks, will identify the agreed alternate routes, comparative distance and travel times, which vehicle types each route is suitable for, and other key pieces of information.

Detour or alternative routes with start and finish points are also a useful method for breaking a long corridor into segments for a more accurate assessment of the resilience risks to a particular area.

You can get further information from the relevant Network Outcomes Contract (NOC) Emergency Procedures and Preparedness Plans either by contacting a regional NZTA office, or for NZTA staff these can be found on InfoHub.

One Network Road Classification assessment

The One Network Road Classification (ONRC) provides guidance for the resilience customer level of service that is expected for each road category (national, regional).

The gap assessment [XLSX, 29 KB] provides a simple table for documenting your assessment against the ONRC. This assessment will help in determining the scale of the problem, and will also help in assessing the strategic fit of the project.

Resilience risk priority

The resilience prioritisation tool, under the Prioritisation Score Tab in MapHUB, lets you look at aggregated or detailed level of resilience hotspots of state highway segments across the network. The purpose of the tool is to help prioritise where we need to focus our attention in improving the resilience of the state highway network. The data is derived from a model that processes a number of datasets and looks at:

  1. Low frequency events (earthquake, volcano, storm, tsunami)
  2. Resilience cost data based on network maintenance costs for key natural hazard faults (slips, ice/frost, flood). Please note that we are reviewing this data source, as it is collected differently across the country
  3. The relative importance of the road segment based on the One Network Road Classification.

Resilience prioritisation tool(external link)

Resilience in the programme business case

The insights report gives examples and insights using a resilience lens on the planning process and can be used by anyone developing a programme business case to incorporate resilience into their assessments.

Resilience business case best practice and insights [PDF, 989 KB]

Detailed data collection

The programme business case stage requires that a more thorough data collection and analysis is undertaken.

Low probability high impacts event:The Resilience of state highways guide builds on the national hazard exposure scan methodology, aligning with the expectation that a more thorough assessment of the problems is explored in the programme business case. The guide steps you through the process of a more thorough assessment at the regional/corridor level, focusing on the natural hazards which are generally low frequency, high impact events (such as a large earthquake).

Resilience of state highways guide [PDF, 1.2 MB]

High probability low impact events: An assessment of the high probability, low impacts events must also be undertaken. This information can be requested from the TREIS database via our regional operational staff (including NOCs and other contractors).

The Resilience high frequency/low impact assessment template will help collate and represent the data from TREIS in a simple way, and can be copied into a report.

Resilience high frequency/low impact assessment template [XLSX, 111 KB]

Assess the level of service gap

A more thorough assessment of the customer level of service is expected in the programme business case, than the strategic case.

This framework takes a closer look at the profile of event outage durations and frequency and recommends a process response type taking the ONRC category into consideration. This will help inform the development and assessment of your programmes.

Resilience customer levels of service assessment tool [XLSX, 488 KB]

The criticality framework is to help refine the importance of your corridor, looking wider than just traffic volumes, by considering access to lifelines utilities and essential service needs. Your local civil defence group might be a good starting point for collecting this information. You can find contact details on the civil defence website.

Assessment of criticality tool [XLSX, 381 KB]
Civil Defence website(external link)

This is a different approach to assessment against the ONRC. This approach considers whether the ONRC classification makes sense from a resilience point of view, and whether the corridor should be treated as either a higher or lower category. In this situation you may need to revisit the evidence base in your strategic case to ensure that it still aligns with the ONRC category.

Develop and assess programme of options

If you identify a gap in the level of service your network provides, you need to develop and test a range of approaches to address this.

The response framework introduces the concept of a hierarchy of interventions. This is to ensure that you have considered all options, before implementing a capital investment.

Response framework [PDF, 542 KB]

The programme business case will guide you through the process of developing these programmes, including a social and economic impact assessment.

Economic assessment: You need to assess the economic impact of your proposed programmes. The Modelling the economics of resilient infrastructure tool (MERIT), which supplements the standard economic evaluation manual-based benefit-cost analysis, assesses the economic impact of a potential (or actual) network outage. The tool and related supporting resources can be found under the ‘Economic assessment’ heading. Work has been done to test the MERIT tool in action, on the SH3 Manawatu Gorge 2011–12 outage.

Economic impact assessment tool
SH3 Manawatu Gorge 2011–12 outage example [PDF, 403 KB]

Social assessment: Similarly you should consider the impact on society if your link becomes inaccessible. The Te Paparanga Āmiki resilience maps include a social impact map theme showing the potential social impacts for communities of particular network outages. These routes were rated for their relative social impact susceptibility based on the number of people affected by loss of access to key hubs providing social services (for the purpose of this framework, any centre that contains a secondary school, a supermarket and a medical centre). This assessment should not be considered to replace the need for a full Social Impact Assessment in later business case stages.

Social impact map theme(external link)

Once you have selected your preferred intervention it is worth reassessing it against the level of service framework to ensure that your invention will close the gap in level of service.

If you have any questions or need further information, please contact