The urgency of upgrading Wellington's earthquake resilience has been laid bare in a new report.
The Lifelines Regional Resilience Project considered what economic impacts there would be on the Wellington region in the event of a 7.5 magnitude earthquake.
It predicted if that were to happen, electricity would be down for up to six months, and some roads around Upper Hutt would be inaccessible to emergency services for around 90 days.
It said the overall cost to national-GDP would exceed $16 billion, and the timeframe for the city to fully recover would take longer than Christchurch.
But the report's main focus details a way out, and the approach necessary to ensure such damage does not occur. It sets out the investment, the timeframe and the approach that is needed to improve the city's resilience, and make these statistics go down.
"We've looked at the economic impact," said Dame Fran Wilde, former Mayor of Wellington and chairperson of the Wellington Lifelines Group.
"What we're suggesting is that all players: the owners of utilities, local government, and central government, all get together and say what do we do to make this happen."
An integrated approach, with all agencies working together is what pleased Wellington City council engineer, Derek Baxter.
"Up until now, each utility provider has done their own planning," he said. "But what this report has been able to do is too look at all those interdependencies, and work out where the critical place for the investment should be."
Interdependencies look at the reliance of different utilities and organisations upon one another - it's where the timeline will be important for setting out what needs to be done and when.
"There is little benefit in having a highly resilient water network, if electricity isn't available for a water pumping station," Dame Wilde said.
"Everything could be out for months if we don't continue with the programme - most of which have already started. And we're suggesting they should be hastened, and we need to be faster, and we need to do them in the correct sequence."
The report split 25 individual projects into three phases, over a timeframe of 20 years.
Phase 1 for example, includes projects such as a Cross Harbour Water Pipeline, seismic strengthening of the port, and a Wadestown to Johnsonville route, which would provide an alternative route for vehicles and fuel to get into the CBD.
"This report is really about how to target the investment first up," engineer Derek Baxter said.
"We're all needing to prioritise our investment and this helps us identify where you would prioritise first."
The projects in total cost around $3.9 billion, and all have a specific purpose for increasing and speeding up the city's ability to get back to normal following such a significant earthquake.
With electricity, for example, resilience hinges upon reducing the dependency on the Central Park Substation, which currently has around 45,000 connections, including Parliament.
The report recommended building a second station by 2024, which Wellington Electricity boss Greg Skelton said they're working on.
"Our view is it's a lot of eggs in one basket," he said.
"A single mode of failure of one big supply point means you've got a lot of people who will have to wait a fairly long period of time without really having a back-up facility to actually put some form of supply while the other supply point was being repaired or fixed."
The result of having a backup facility would mean electricity could then support its interdependents: other lifelines such as water and telecommunications.
Regional council chairperson Daran Ponter said he saw their role as largely acting as an intermediary between agencies to turn these projects into a reality.
"A lot of the projects that you see in the lifelines are things that are already in the pipeline," he said. "The useful aspect of the lifelines work is it's brought all of that stuff together."
"There's a strong advocacy role for the regional council, and its role as an integrator," he said.
"Bringing various parties together is quite significant, particularly working with such organisations like NZTA, particularly around roading."
While there will be no organisation overseeing progress, it is hoped this report will now provide the framework each agency involved can look to.