A resilient transport network helps the Transport Agency to be responsive to unforeseen events and provides customers with confidence that they will be able to undertake their journeys in a timely manner. Managing resilience involves targeting the risk of anticipated disruption on the network.
Investment varies widely across the programme. Examples include:
Research is also underway to better quantify the benefits of improving network resilience, enabling more consistent prioritisation of investments.
New Zealand’s topography, climate and exposure to seismic events mean that there will always be a risk of network disruption. A range of work is already underway to help increase resilience. This includes physical works, such as bridge strengthening and slope stabilisation, and using traffic operation centres to keep people and vehicles moving. Resilience is also about minimising the impact of disruption. Emergency response planning helps ensure that networks 'bounce back' as soon as possible following a disruptive event.
Resilience in rural and urban areas tends to take different forms. Disruptive events in towns and cities tend to be caused by technical events such as breakdowns or crashes. While they are often resolved quickly, the impacts can be significant due to the number of users, the lack of spare capacity on congested networks and the inability of alternative routes to cope with additional traffic.
In rural and provincial areas network disruption is more commonly caused by environmental or weather events, such as landslips, flooding, snow and ice. While traffic volumes tend to be lower than in urban areas, a lack of viable alternative routes can cause significant disruption.
The 2015 Government Policy Statement focuses effort on 'improving the system’s resistance to disruptions that pose the highest economic and social cost'. While the economic cost of disruption is closely tied to the volume of people and goods using a section of the network, work to improve understanding of the social cost of network disruption continues. This work will inform the development of the 2018–21 NLTP.
Resilience improvements can underpin many different types of investment. More than half of improvements activities include some resilience benefits for the network. This is despite only 2% of new improvement activities being primarily targeted at resilience.
Travel over the Southern Region’s alpine passes, such as State Highway 73 that connects Canterbury to the West Coast, can be challenging for the tourists, freight drivers and locals who traverse them. As the highways are often cut into the side of steep, mountainous terrain they are narrow and prone to rock falls and slips during periods of rain or snow.
In September 2013 a large landslip closed State Highway 6 on the West Coast between Haast and Makarora.
On 20-21 June 2013 a severe storm hit Wellington, causing significant damage and disruption to the region’s transport network. The immediate impacts of the storm included ferry cancellations, road closures (due to debris and storm surge), airport and rail line closures and disruption to bus services.
Prior to the 2011 Canterbury earthquakes the township of Lyttelton and Lyttelton Port (the largest port in the South Island) were serviced primarily by the Lyttelton Tunnel. Sumner Road provided the designated regional lifeline route and was used for the movement of hazardous goods and overweight and over-sized vehicles between Christchurch and Lyttelton.