On this page:
2014 information boards
Northern Wellington SATURN Model Update
Meeting notes from P2G Design Surgery
Petone to Grenada Scoping Report 2014
- P2G Project update – October 2016 [PDF, 131 KB] – 21 October 2016
- P2G Project update – April 2016 [PDF, 578 KB] – 30 April 2016
- P2G Project update – December 2015 [PDF, 421 KB] – 11 December 2015
- Preferred route now confirmed [PDF, 2.5 MB] – 17 November 2015
- P2G Email update – July 2015 [PDF, 231 KB] – 27 July 2015
- P2G Project Development Diagram [PDF, 873 KB] – 9 July 2015
- P2G Email update – April 2015 [PDF, 221 KB] – 7 April 2015
- P2G Email update – December 2014 [PDF, 246 KB] – 10 December 2014
- P2G Email update – September 2014 [PDF, 280 KB] – 2 September 2014
- P2G Project update – February 2014 [PDF, 1.4 MB] – 13 February 2014
The idea of developing a link road between SH1 and SH2 has been considered in a number of studies. The first time the route was identified appears to be in the 1975 Wellington Region Land Use and Transport Study. This was followed by the Greater Wellington Land Use and Transport Strategic Review indicating the route deserved further study in 1988. The first detailed study of the link happened in 1991.
The studies have included:
- SH1 Inland Route Review of Southern Sector – Petone to Grenada North Link 1991 (Works Consultancy Services)
- Petone to Grenada Link Study 1995 (BECA)
- Hutt Valley – Porirua Link Initial Appraisal of Possible Links Working Paper for Steering Committee Consideration 1996 (Works Consultancy Services)
- Hutt Valley – Porirua Road Link Study Feasibility Investigation Report 1997 (Opus)
- Ngauranga Triangle Strategy Study – Detailed Technical Report 2009 (SKM)
- Ngauranga Triangle Strategy Study – Petone to Grenada Link Road Project Feasibility Report 2010 (SKM)
All of these studies identified the need to relieve congestion on SH1 and SH2 north of Ngauranga Gorge and improve regional connectivity between the Hutt Valley and areas north of Grenada.
We have drawn on information from all these studies, to help identify key issues and develop options. A variety of routes have been considered between Petone and Grenada, including a link to the former Transmission Gully route near Tawa, which was identified in the 1991 study.
Early studies proposed routes that travelled over the hill north from SH2 at Petone through the Korokoro Valley in Belmont Regional Park. The most recent study avoided this area by travelling over the hill west across the coastal escarpment of the Wellington fault from Petone at SH2. This study also proposed a full interchange at Petone, south facing ramps at its connection to SH1 at Tawa and a connection midway to provide access to the Lincolnshire Farm Development and Horokiwi Road.
Petone to Grenada imitates historical route:
The general location of the route options we’re suggesting for the new Link Road has historically been used for travel between the Hutt Valley and Porirua.
Our research found that early European settlers in the district writing about how they travelled in the early part of the 19th century did so for the most part on well-used old Maori tracks.
In the 1880s, prominent Wellington settler James Coutts Crawford wrote about his journey from the Kapiti Coast to Port Nicholson following his arrival in New Zealand in late 1839.
“Passing Titahi Bay, and the pretty shores of Porirua, we entered the main bush, and travelled up the stream, in a line with whose course the present road stretches. We crossed and re-crossed the stream about seventy times, until at length the path ascended and led us over the summit of the range overlooking Korokoro. The whole distance traversed, with the exception of some few patches of cultivation at Porirua, was through dense and uncleared forest. … The Hutt Valley presented a dense forest of gigantic trees, and a large pa was visible at Pitone. As we descended the hill, our advance was hindered by a mass of newly-felled forest, which was cleared and ready for burning off. Our escort now commenced firing guns to attract the attention of the fishermen; and as we descended the hill the canoes approached the shore, so that when we reached it, they were there to meet us.”
(Coutts 1880: pp 27 -28)
Elsdon Best (quoted in Carman) also reports that many of the first journeys by Europeans through the district were made using “old Maori trails”, the main one running over the hills from the Korokoro Stream to Tawa Flat and on to Porirua.
After the Petone settlement was removed and relocated to its current site of Wellington City, the track from Kaiwharawhara across Paerau hill was used more. This track joined with the Korokoro track at Takapu and then carried on to Porirua.
Best describes the Korokoro track as beginning on the south side of the Korokoro Stream, close to the mouth. It then ascended through bush up a steep hill and followed the ridge line to the Takapu Valley to the Kenepuru Stream and on to Porirua (marked in red, Figure 9-3).
Frequently asked questions
- General FAQs
- Programme and dates
- Public and community
- Route options
- Engineering and design details
- FAQs related to discounted options
- Evaluation report
- Preferred alignment
- Previous questions (February 2015)
1. General FAQs
- What is the Petone to Grenada Link Road?
It’s a potential new transport link between Tawa/Porirua and the Hutt Valley that is expected to help meet the region’s economic and transport needs for the future, while improving travel on two of Wellington’s main highways and resolving some critical issues that affect our ability to manage major events. The Link Road would run roughly between Grenada on SH1 and Petone on SH2. We don’t know exactly what the Link Road will look like at this stage, but it is likely to be an 80km/h road that is four lanes wide separated by a barrier in the middle.
- Why do we need the Link Road?
Transport in the Hutt Valley and through the Ngauranga Gorge plays an important role in our everyday lives. These corridors support public transport links, walking and cycling, freight movement and community travel along Wellington’s two primary highway routes. The SH2 route in particular is vulnerable as it is affected by daily congestion in peak hours, unreliable journey times, delays and a lengthy detour via State Highway 58 (SH58) if the road is closed or blocked. For SH1, there is significant congestion in the morning and afternoon peak periods, which needs to be addressed to support the efficiency of the Wellington Northern Corridor between Ngauranga Gorge and the SH1 connection with Transmission Gully.
These travel issues affect more than 3000 vehicles an hour in each direction on both SH1 and SH2 creating personal, business and economic problems for the region. It clearly indicates both highways are reaching capacity during peak periods and that improvements need to be made to ensure the transport network in Wellington does not limit our potential for growth, our ability to get goods and services to market quickly and easily, cause people difficulty when travelling for work, education, health or family reasons or isolate parts of Wellington in bad storms, earthquakes and when sea levels rise.
- What are the benefits of the Link Road?
- It has the ability to reduce congestion on SH2 and SH1 and can also:
- Make peak morning journeys between the Hutt Valley and Porirua around 10 minutes faster and 7km shorter
- Provide alternative routes when SH2 or SH1 are blocked or congested
- Support better public transport access (particularly for buses) to/from Wellington, Porirua and the Hutt Valley by improving traffic flow and creating the opportunity for new routes
- Support more walking and cycling opportunities, particularly if combined with the Wellington to Hutt Valley Walking and Cycling Link
- Make travel times on SH1 and SH2 more reliable
- Open up future residential or business growth opportunities by making Porirua, Wellington and the Hutt Valley better connected.
- How does this project fit in the wider transport network?
We completed three transport studies to help inform our decisions on the Link Road. These studies considered the benefits of improvements to the existing highway routes of SH2 and SH58 and the potential to create a new Seaview Link. By completing these studies we can be more certain that we are unlocking the greatest benefits possible in the area because we can understand if the other improvements would achieve similar benefits for similar costs as the new Link Road. A brief summary of these studies is available in our February newsletter on page 6.
Back to top
2. Programme and dates
- When will the project be built?
The project is at an early stage and it is typical for timeframes to change over time, especially prior to the investigation phase. However, at this stage, we expect that the project will begin construction in 2019 and be completed by 2023.
- Can it be built any sooner?
We are considering tolling the new Link Road as this could enable it being constructed earlier, realising the transport and wider economic benefits sooner. Based on some early assessments, we believe this road could be a good tolling prospect because of the significant travel time savings and high traffic volumes expected to use it, particularly at peak times. Before tolling is considered any further, we need to consult all the affected communities and stakeholders more widely on a detailed proposal that would include the likely operational costs and economic benefits/impacts of tolling, potential impacts that tolling infrastructure (ie location of gantries) would have on the proposed road alignment, connections and interchanges, and possible toll prices. We are interested to get your feedback on this suggestion so please tell us what you think on one of our submission forms. We are interested to get your feedback on this suggestion so please tell us what you think.
- When will you be talking to stakeholders?
We have been engaging with key stakeholders for the past year and began talking to affected property owners this year about our proposals. Public information days were held in February to provide local communities and the wider public with an opportunity to find out more about the Link Road. We expect to have confirmed a preferred option for the route to support better east-west travel in the Ngauranga Triangle area by the end of this year and will next be talking to stakeholders at this time.
Back to top
- How much will it cost?
Our initial estimated cost for Petone to Grenada is $250-$270 million, but we won’t have a detailed cost until the investigation phase is completed. However, we will develop our initial design of the project with the goal in mind of minimising cost while achieving the best outcome for the state highway network.
Back to top
- How many properties will be affected?
We won’t know specifically how many properties will be affected until we have developed land requirement plans. However, our initial designs have been developed to minimise property effects. Later in the process, affected property owners will be entitled to fair and reasonable compensation for any impact on their land. At this time about 38 individual land owners are affected and fewer than 15 homes are likely to be affected.
- If I am affected, when will you buy my property?
At this time we cannot be sure which properties our proposals will definitely affect and how much land would be required and we are only able to buy properties once we have firm land requirement plans in place. The timing of this will depend on the outcomes of consultation, more detailed investigations and consenting. Construction timing is also a consideration.
Back to top
5. Public and community
- Will I be compensated for the road being moved closer to me?
We only compensate landowners whose property, either fully or partially, is required for a public work (ie for the Link Road). This is set out in the Public Works Act, therefore we can only pay compensation in these circumstances. As part of our consenting process, we will look at opportunities to minimise and mitigate the impact on nearby properties.
- What is the purpose of the community engagement report?
The engagement report outlines comments made by stakeholders and the community, who were engaged with earlier this year regarding proposals for a new east/west link between Petone and Tawa/Porirua. Consultation took place from 22 February through to Easter (April) 2014.
- What are the outcomes of the community engagement report?
The report confirms there is general support for the Link Road, particularly between Petone and Grenada North. A number of questions and concerns have also been raised. There is clear support for the option proposed between Petone and the Crest of the Wellington Escarpment, and no clear preference for either option between the Escarpment and Tawa or Transmission Gully.
- What are the next steps now that the report has been finalised?
The report forms a vital part of the discussions we are having with our partners, and the joint Chief Executive’s group in particular that will consider what improvements will best meet the region’s economic and transport needs for the future. A decision is expected later this year on the preferred option for the project north of Tawa.
Back to top
6. Submissions from 2014 consultation
- Have submissions been made public?
Private information has not been made publically available, but our engagement report, which summarises the feedback provided from our 2014 engagement, is publicly available on our project website. Please refer to the publications page under the heading “reports”.
- How are submissions counted and assessed?
Submissions are all counted and assessed on an individual basis. Submissions are generally given more weight according to the depth of their content, regardless of where they come from, either from an individual, an informal group or an established community or resident group. Because of this, the outcomes from the submission process may not directly reflect the actual number of submissions received, but rather the content of the received submissions.
From a purely numerical point of view, each submission received is counted as one submission whether it has one signature or 10. While 10 identical submissions with one signature will be counted as 10, they will be given the same weight as one submission with 10 signatures because they do not provide any new information. It is also worth noting that consecutive submissions made by one submitter will be added to their original response and considered as one submission.
- What is the legal status of the submission process?
The submission process last year (February-April 2014) is an informal process used by the project team to gather feedback from the community on the project in general and the options being considered. Enough time was allowed so the feedback could be collected and collated into a report. This report forms part of the background documentation for the project and will inform the upcoming project decisions.
The submission process does not form part of the legal resource consent process which is governed by the Resource Management Act. A separate submission process with formal/legal notification and legal timeframes will take place as part of the resource consent process.
Back to top
7. Route options
- Could SH58 be improved as an alternative to this route?
The upgrade of SH58 from the new Pauatahanui interchange (part of the Transmission Gully project) to Haywards was investigated as part of this study as an alternative to P2G. It is important to understand that the purpose of P2G is not just for users from Paremata and north to get to the Hutt Valley. There is a significant demand between Tawa and the Hutt Valley which increases if P2G is built. For anyone in Porirua and further south wanting to reach the Hutt Valley the direct distance is significantly less for P2G when compared with SH58. Travel times for key routes are shown in Figure 13-12 and Figure 13-13 in the Scoping Report. These figures show significant reductions in the travel times of the P2G options compared to the Do Minimum. We have modelled the upgrade of SH58 to four lanes from the new Pauatahanui interchange on Transmission Gully to SH2, but it does not attract significant traffic off SH1 or SH2 since the route down SH1 and turning back north onto SH2 at Ngauranga is still shorter for many road users than using SH58.
View larger image
One of the other key objectives of the Petone to Grenada link road is to improve network resilience to earthquakes, crashes, slips etc. and to improve connectivity between SH1 and SH2, since both SH1 and SH2 in the Wellington region are vulnerable to these events and the current diversion route (along SH58) is a significant distance and SH58 is itself vulnerable to seismic events. It is worth noting that the P2G link road is endorsed at a regional level in both the Hutt Corridor Plan and the Western Corridor Plan.
- Has the concept of a route through Takapu Valley been suggested previously?
Yes the concept of a route through Takapu Valley was considered at the southern end of the Transmission Gully Project. As part of the Transmission Gully designation process a number of alternative alignments for the southern tie-in were considered. Indicative locations of these southern alignment options are shown on Figure 2.2 of Section 2 of the Assessment of Environmental Effects for Transmission Gully. Two of these alternative alignments ran through Takapu Valley (identified as Option B and Option C on Figure 2.2 of Section 2). However, these alignments are in a different location than the one which we considered for the Link Road. This is illustrated in the figure below which shows these two alternative alignments in relation to the one which we considered for the Link Road.
Back to top
8. Engineering and design details
- What improvements will be included for walking and cycling?
In parallel with our Link Road investigations, we are considering options to deliver a safe and efficient route for cyclists and pedestrians between Ngauranga and Petone along SH2. The Wellington to Hutt Valley Walking and Cycling Link aims to “close the gap” along the existing cycleway on SH2, improve the current facilities for pedestrians and cyclists and encourage more people to walk, run or cycle between the Hutt Valley and Wellington.
For more information on this project please visit the project website at www.nzta.govt.nz/w2hvlink
- How much of the alignment can be moved through further design?
We have significantly adjusted our alignment following public feedback. We will continue to consider improvements to the alignment before finalising our consent applications.
How steep will the road be in comparison to Ngauranga Gorge?
Between Petone to the crest of the Wellington escarpment, the gradient will be similar to that of Ngauranga Gorge. The Link Road is proposed to have a 9% gradient while Ngauranga Gorge is 8%.
- Why do we need more capacity north of Tawa?
As part of our investigations into the new Link Road, we have identified a need to respond to future traffic growth on SH1. This is needed because the Link Road will draw traffic away from the SH58 Haywards route and southbound traffic will instead travel along State Highway 1 between Porirua and Tawa en route to the new Link Road. Given that the Link Road reduces journeys by approximately 7km, traffic modelling predicts that more capacity may be required on SH1 north of Tawa as road users take advantage of this shorter, more fuel-efficient route.
Will noise levels increase as a result of the highway being moved closer to residential properties?
We will carry out detailed noise assessments at a later stage as part of the process to seek RMA approvals. This will tell us how noise levels may change. We need to mitigate the effects of new/altered roads, particularly if we identify that noise levels could increase.
- How many vehicles are predicted to use the new Link Road?
We have projected that there will be an average daily tally of 30,000 vehicles using the new Link Road. If Option C is preferred, roughly a third of these vehicles will enter/exit the road at Grenada, while two-thirds will enter/exit at Tawa. If Option D is chosen we anticipate a third will enter/exit at Grenada, a third at Tawa and a third with the connection to Transmission Gully.
Back to top
9. FAQs related to discounted options
- Why were you proposing to widen the highway on both sides in the Option C proposal?
It is easier to extend the road on both sides evenly than it is to extend it on only one side. This is because the highway is not actually level from one side to another. Instead, if we took a slice of the road and looked at it separately, we would see it looks like an upside down W with low points in the middle and on the shoulder of the road.
It is much simpler, less disruptive and less costly if we widen from the road’s existing location. If we widen the road by extending the width from only one side we would have to rebuild the whole road. This reconstruction would require the median strip being relocated and could affect drainage and other infrastructure which is often located there. This is what makes this type of extension more costly, more disruptive and less preferable.
Back to top
10. Evaluation report
- 1. What is the status of the project?
In May 2017, during development of the business case, we began a comprehensive internal evaluation of the scheme. The evaluation is complete and we will engage with our local council partners on the next steps.
- 2. Why did the Transport Agency undertake an evaluation of the project?
As part of any investigations for significant transport proposals, we frequently test schemes to ensure that they are fit for purpose. This evaluation of P2G was part of this internal quality assurance step. The evaluation was driven in part by concerns about whether the scheme reflects the current emphasis being placed on resilience in the Wellington region following the Wellington and Kaikoura earthquakes.
- 3. What are the next steps?
We are essentially taking a new look at the design of the current scheme. Along with our council partners, we will consider the merits and feasibility of each recommendation in the evaluation. We’ll work closely with councils to re-test the project objectives and to consider the impact of new growth assumptions on traffic modelling.
- 4. Why has it taken you so long to update the public on the status of the project?
We had planned to engage on the preferred alignment and interchange designs in early 2017. However, we chose to evaluate the project due to the renewed emphasis on resilience after the Kaikoura earthquake and recent legislation and policy changes.
The evaluation was only recently completed. We are now ready to talk with the community about the results and next steps. Next year we will also lay out how we will engage with the community going forward.
Evaluation findings and recommendations
- 5. What did you learn from the evaluation?
The evaluation examined the current P2G Link Road scheme’s project objectives, costs, key design decisions, anticipated environmental impacts and the interchange design options.
The project evaluation found that:
- the current alignment may not provide the lifeline resilience outcomes first anticipated because the very high “vertical cuts” would be susceptible to landslides following a major (7.5 magnitude) earthquake
- the project objectives may not reflect the high priority now being placed on resilience by local and central government
- expected costs could be significantly higher than first anticipated
- environmental impacts of the current design may be difficult to mitigate.
- 6. Why was P2G being designed to expressway standards?
We have designed the road to a six lane expressway standard based on projected traffic volumes and for safety reasons. Our current predictions indicate that up to 30,000 vehicles per day will use the road by 2031. Generally four lanes are needed to accommodate this amount of traffic.
The road design has been adapted to “fit” with the local terrain. This has led to sections of the road at the Petone and Grenada ends of the link being very steep and requiring extra crawler lanes for slow moving trucks. This has resulted in six lanes along the general alignment.
We expect a new link between Grenada and Petone to be popular for two reasons. Firstly, commuters who currently travel between Porirua and Hutt Valley will switch to the link road (because it could save up to 30 minutes) and others who had not previously made this trip will start making it because it will be easier to reach destinations that were previously difficult to access.
The evaluation recommends reconsidering P2G’s project objectives, including whether to pursue an expressway standard. This is a fundamental question that we and the councils will consider.
The evaluation has also recommended that we revisit traffic growth assumptions and further consider travel demand measures (e.g. high occupancy vehicle lanes and bus priority lanes). These factors will be important when reconsidering the expressway standard objective.
- 7. How quickly would P2G need to re-open following an earthquake in order to be considered ‘resilient’?
The current scheme could be partially reopened to provide limited access within three to seven weeks following a 7.5 earthquake. Full restoration may take up to 3 months. This restoration time is considerably shorter than what is expected for the section of SH2 between Ngauranga and Petone.
We don’t yet have a specific target that P2G would need to meet in terms of when we would expect it to reopen following a major event. That’s something we’ll consider when reviewing and prioritising the project objectives.
- 8. Did you learn anything from the earthquake that contributed to you deciding to re-evaluate P2G?
An independent ‘lessons learnt’ report was undertaken following the Kaikoura earthquake in late 2016.
The report compared the performance of SH1 with the predictions made by previous resilience assessments, in particular the National State Highway Resilience Study that was completed earlier in 2016. It made a number of observations regarding the earthquake that should be taken into account when planning future projects as well as for post-quake response planning.
The report concluded that our predictions about the vulnerability of SH1 to a significant earthquake and amount of time it would take to restore SH1 following such an earthquake were reasonably accurate.
The report’s key recommendations included:
- Highways in steep terrain are more susceptible to landslides and debris flows in storm events (and hence are less resilient) for a period of many years to decades after being subject to major earthquake shaking events.
- The conclusions from the review should be incorporated into the methodology developed for regional resilience studies, to inform future regional or corridor level resilience assessments.
- The observations on post-earthquake resilience and response planning should be made available to regional land transport teams involved in planning post-earthquake response.
Accordingly, the lessons learnt from this significant earthquake need to be taken on board, especially given that the P2G project area lies within the Wellington region, which is prone to earthquakes.
The report, released in mid-2017, can be found at: www.nzta.govt.nz/roads-and-rail/highways-information-portal/technical-disciplines/resilience/resilience-planning-tools
Recent geotechnical investigations for the Petone interchange have also indicated that there might be fault splays (fault splinters) associated with the nearby Wellington Fault. The risks posed by these splinters need to be considered very carefully from a design perspective.
- 9. What legislative and policy changes have been made around resilience?
There have also been some important legislative and policy changes relating to resilience that has come into force this year.
Section 6 (Matters of National Importance) of the Resource Management Act has recently been amended (it came into force in April 2017). The amendment says “all persons exercising functions and powers under [the Act]….shall recognise and provide for the following matters of national importance…. (h) the management of significant risks from natural hazards”. This change will be an important consideration for any future consenting process for the scheme.
Also the draft Government Policy Statement on Transport places further emphasis on the importance of planning for resilience. It also requires us to take a ‘whole of system’ view for cost effective mitigation or adaptation when dealing with resilience risks.
- 10. What size earthquake is the scheme road being engineered to? How will that change?
The Wellington fault is close to the proposed Petone interchange. The fault has a recurrence interval of 610 to 1,100 years and ruptures in large earthquakes of magnitude 7.5.
The recently developed scheme has been designed in accordance with NZTA’s guidelines and manuals. Key structures, including interchanges and bridges, have being designed to withstand a 1:2500 earthquake event.
Road cuts, embankments and retaining walls have been designed for a lesser event (500 to 1,000 year earthquake events). We have taken this approach because bridges are vital for restoring transport access in the first instance. They are also most expensive aspect of a new road to repair following an earthquake.
The road cuts for the current scheme are designed to have larger, regular benching. Larger benches can capture debris and be cleared for recovery purposes.
The evaluation has recommended that we look at ways to reduce the resilience risks associated with the steep slopes. Options include revisiting the alignment and considering tunnels.
- 11. Given the challenging topography, is it possible to build a link road that will be more resilient to significant earthquakes, like a 7.5?
A new link is vital for increasing lifeline services to our communities, particularly in the Hutt Valley. The link will also be very important for day-to-day operational resilience (e.g. accidents on SH1 or SH2). Any new roads in Wellington are likely to be located in challenging terrain.
The evaluation noted that the cuts for the road will be high and very steep, and therefore may be susceptible to landslides during a significant earthquake. In light of the evaluation concerns, we will reassess the risks associated with the sections of the current scheme that are of most concern from a resilience standpoint and explore options for improving their resilience.
The evaluation has recommended looking at ways to improve the resilience risk associated with the steep slopes. Options include revisiting the alignment and considering tunnels.
- 12. The evaluation found that costs are significantly higher than first anticipated. Why is it so much more expensive than the original estimates?
The evaluation has considered the latest P2G Link Road scheme design costs. It found that costs have gone up from the original estimate of $250-270M for the 2015 preferred option.
It is now estimated the project could cost up to $1.2B. Our understanding of the scheme that was first identified in 2015 has advanced considerably. The current cost estimates reflect what we have learnt about the scheme since then.
When we announced the preferred alignment for the P2G link road in 2015, we had not yet developed detailed plans for the key interchanges. We have now completed more detailed interchange designs with a focus on ensuring that they are safe, efficient and resilient. Development of the interchange designs have been one of the main reasons for the increase project costs.
While the cost of the interchanges is one of the key reasons for cost increases, the following changes have also increased costs:
- mitigation for environmental and stakeholder impacts such as the Belmont Bridge and the Bush to Beach walkway
- provision of grade separated connections to Horokiwi and the new Lincolnshire Farm development
- upgrades to SH1 between the Transmission Gully interchange and the Grenada interchange, and potential upgrades to SH2 north of Petone
- greater allowances for project management and contingency.
The evaluation’s high level cost review also recommends that further allowances be made for project management, contingency, traffic management and spoil displacement.
We will review the current estimates for the scheme and the assumptions underpinning them and consider the cost saving opportunities identified by the evaluation.
- 13. Has the benefit cost ratio changed?
Yes. The increase in costs has led to a drop in the benefit cost ratio from 4 to somewhere between 1 and 2. We expect to further refine costs and benefits as part of the next phase of investigation.
- 14. How much has been spent on the project to date?
$9 million has been spent on early property purchases. An additional $9 million has been spent on investigations, which is consistent with expenditure on other projects of a similar size. Expenditures on property purchases can be recouped if made necessary by project changes.
- 15. What were the stakeholder and environmental impacts?
As with any large scheme, there will be effects on the local environment and impacts on local communities from construction. These effects and impacts need to be carefully considered and mitigated where possible. The evaluation has found that some of these impacts may be challenging to mitigate.
Some of the effects the current scheme is expected to have include:
- ecological effects (e.g. terrestrial, freshwater and marine)
- landscape and visual effects, especially at the Petone end of the scheme
- recreational access and local historical effects.
There will be access changes for some the local communities such as Horokiwi and a number of existing properties will be affected by the alignment and the new interchanges. In particular, the proposed SH2 interchange will require us to acquire land occupied currently by commercial properties located on Cornish Street and Pito One Street. A number of these properties are already owned by the Transport Agency.
Flow-on effects of delay
- 20. The feasibility of this route has been studied numerous times since 1975, is it possible that it will never be built due to the difficult topography and high costs?
The existing topography makes constructing a road in the Petone to Grenada location a complex undertaking. We are, however, building other projects in the region as well as throughout New Zealand where there is equally challenging topography (e.g. Transmission Gully). The key learnings from constructing these projects will be applied to this project in due course.
We do know that constructing roads in complex topography comes with added costs. Detailed investigations to date have given us an improved understanding of the likely cost of constructing a new link road in the Petone to Grenada location.
The evaluation has recommended that we explore cost savings by reconsidering the project’s objectives and by also adjusting some of the project’s key scope elements.
- 21. Would four-laning SH58 accomplish the same objectives of P2G at a lower cost?
21. Would four-laning SH58 accomplish the same objectives of P2G at a lower cost?
We have considered this option. We don’t believe this option provides an adequate alterative to P2G, because it would not:
- improve lifeline services for the lower Hutt Valley, and the wider region
- enable housing development in the Lincolnshire Farm area
- address the capacity and safety issues on SH2 between Petone and Ngauranga nor on SH1 between Linden and Ngauranga.
Safety is the key priority on SH58, which is why we have proposed significant safety upgrades to SH58.
Back to top
11. Preferred alignment
- 1. What are the benefits of the Petone to Grenada Link Road for the Wellington Region?
Beneifts of the new transport route include:
- Keeping the Hutt Valley better connected in an earthquake, slip or crash
- Creation of several hundred brand new jobs and facilitating growth in areas like Lincolnshire Farm, Porirua & Seaview
- Saving every commuter between Porirua and the Hutt Valley around 30 minutes [return journey] per day in peak travel
- A new interchange at Petone, a key bottleneck, making journeys smoother and faster along SH2 and the Esplanade
- Providing better connections for communities such as Grenada North and facilitating improved connections & access to Belmont Regional Park
- Fill from the construction of the Link Road could be used to build the cycleway between Petone and Wellington or for other construction activities nearby.
- 2. How will we manage any future increased traffic demand on SH1?
We are exploring options to implement a ‘managed motorway’ which would work much like the Smart Motorway, which will open on the Wellington Urban Motorway next year between Thorndon and Johnsonville. This is an internationally proven concept that focuses on optimising traffic flow through speed limits and lane controls. We can also increase traffic capacity within the existing motorway footprint by utilising the existing shoulders. We will be examining the performance of the Wellington state highway network in the coming years to investigate where managed motorways could optimise traffic flow.
- 3. What were the options for the north of Tawa section?
The Transport Agency was previously considering three options with regard to projected traffic growth north of Tawa – widening the motorway north of Tawa to six lanes building a two lane link road through Takapu Valley (both of which would have required significant property acquisition), or to retain the existing corridor and monitor future traffic growth (with minimal property impacts).
We have proceeded with the third option approach, with a potential managed motorway approach to be pursued to help future proof against traffic capacity constraints. This involves minimal property impacts. A managed motorway will only be implemented when it is required.
- 4. What work was this decision based on?
The Transport Agency is committed to ensuring all major transport decisions are made with expert technical advice, extensive community and stakeholder involvement, and a robust evidence-based approach. The process to determine a preferred route has been significant, including advice from a range of technical experts, briefings, workshops and presentations, landowner meetings, thorough examination of all potential options, extensive transport modelling and investigation work, and consideration of environmental and property impacts, along with land use development and transport resilience matters.
- 5. Will you be using fill (dirt from earthworks) to reclaim the harbourside?
Where possible the Transport Agency will look to align construction of the Wellington to Hutt Valley Walkway, Cycleway and Resilience project with the Link Road. This could include making use of fill to help reduce the costs of this project’s preferred option between Petone and Ngauranga. However, while this would be an added benefit from dovetailing the projects, the cycleway is not dependent on the Petone to Grenada Link Road in order to progress.
- 6. What next – and will I get another chance to have a say?
Work to prepare RMA consents is likely to continue through to late next year. Part of this work will be to prepare an Assessment of Environment Effects and consider how to mitigate any of the adverse effects of the Link Road on the environment and people living in the area.
The public will get another opportunity to provide input on the initial design of the preferred Link Road route and suggest ways in which we can limit things such as construction impacts, noise and urban design and so on.
At this stage, the Transport Agency expects to lodge its consent applications in late 2016. Construction of the Petone to Grenada Link Road, assuming consent is granted, is scheduled to begin in 2019.
Back to top
12. Previous questions (February 2015)
- 2. Have plans been designed knowing the results of the geological investigations already?
The existing alignments have been developed to locate the interchange away from the known location of the Wellington Fault zone. The geotechnical investigations into the Wellington Fault zone are ongoing, and we will further refine the project layout as necessary as more information becomes available. Similarly based on the liquefaction risk assessed from the geotechnical investigations, the design for the interchange will be developed to achieve resilience.
- 4. Is the Link Road compatible with future regional road plans?
The proposed P2G route will improve resilience in combination with the Transmission Gully scheme to the north, and enable access to be more quickly restored to the Hutt Valley in the event of major earthquakes. In conjunction with a potential Cross-Valley Link, it will improve resilience to access to the eastern areas of Hutt valley including Seaview and Wainuiomata.
The proposed route will also complement improvements on SH2 and SH58, including the new SH2/SH58 Haywards Interchange, for which construction is underway.
- 8. Is the current design of the Petone interchange focused more on moving traffic west over P2G route?
The current thinking has traffic from the Esplanade and traffic from P2G having similar priority. Both the Esplanade and P2G approaches to the interchange have a free left turn, two ahead lanes and a single right turn lane. The left turn lanes (to Wellington from the Esplanade and to Lower Hutt from P2G) will receive the highest priority in order to accommodate the volumes of traffic, although signal timings can be adapted as vehicle flows change.
- 9. How and where will the Cross Valley Link connect with SH2?
We have carried out an investigation on behalf of Hutt City Council into links with Seaview, colloquially referred to as the Cross Valley Link. This work has identified options for improving capacity between SH2 and Seaview. The main options involve either an upgrade of the Esplanade, a connection via Wakefield Street/Whites Line or using the railway corridor to the south of Wakefield Street.
- 12. What public transport routes would use P2G?
At this time no new specific bus routes have been identified, but modelling indicates that there would be demand for public transport services using the P2G route. The modelling undertaken to date has included potential new bus routes between Johnsonville and Lower Hutt CBD (via Lincolnshire Farms), Lincolnshire Farms to Lower Hutt & Johnsonville and Waterloo and Porirua (via P2G). In practice, decisions would be made nearer the time with GWRC specifying new routes for the operation of new bus services.
The traffic effects of Plan Change 29 (Proposed zoning change to the western end of Petone - Petone Mixed Use) were covered in that application. Changes in transport demands from the plan change are not included in the current regional strategic model (WTSM 2011). However, they will be included in the next WTSM model update.
- 16. Will P2G have a cycle path?
Our initial work has indicated that there is likely to be demand for cycle facilities along P2G. As part of the next phase of works we will work to determine what provision for cycling we can include in the scheme design.
- 18. How often have predictions for traffic/population growth changed over the period of these motorway studies?
The Regional Council’s transport models use census data and estimates of future population and employment to generate predictions about future travel patterns. The model is updated on a five-yearly cycle. It was updated in 2006 and again in 2011 and is presently being updated to incorporate 2013 Census information. This information has also been used to review inputs to the models for application to the P2G project. Over the course of the Petone to Grenada project, the model has been updated once.
- 19. When were Iwi last updated?
A number of meetings have been held with different iwi groups over the past 12 to 18 months. Our agreement with Iwi is that we will update them on any changes to what we are proposing.
- 24. Why were the project objectives for the Link Road changed?
The initial project objectives were broad and pre-dated current policies and strategies. They were refined to more specifically capture the economic and transport-related benefits (and other matters) that the Transport Agency is seeking to achieve through the project.
Back to top