Kia ora and welcome to the Summer 2018 update from the Transmission Gully team.
2018 has been a big year for the Transmission Gully Project with works progressing rapidly.
As much of the project work has gone on behind hills and out of the public eye, this newsletter will showcase a few before and after images so you can see how the project has moved forward.
Many people are involved in the delivery of this nationally significant project – and we’re proud to employ some of the most skilled people from around the world for this work. Last month the project clocked over five million work-hours to date – a huge number that will continue to grow as we get closer to the finish line!
From all the team involved in the Transmission Gully Project we’d like to thank you for your patience and support for our work and we wish you and your loved ones a safe yet fun Christmas and New Year. See you in 2019!
Southbound view of the new piece of local road that opened in December 2018.
The 27km long Transmission Gully motorway project has reached a significant milestone with the first stretch of final road surfacing work just north of Paekākāriki.
Applying the final chip-seal surface and line-markings were the last steps in the construction of a new section of road that will be used temporarily to connect the existing SH1 coastal route and Kāpiti Expressway at Mackays Crossing.
On the night of Friday 14 December, traffic was moved over to the new coast road connection. We need to shift traffic off the current SH1 route in the area so that we can construct the new SH1 connection between Transmission Gully and Kāpiti Expressway with minimal traffic disruption.
Once the new motorway opens, this road will become the new local road connection between Mackays Crossing and the existing coastal route and the Paekākāriki township.
CPB HEB Construction Director Justin Redelinghuys says that this is an important step for the project and is the first finished piece of road along the project that can not only be seen but also used.
“Progress at Paekākāriki, Pauatahanui and between Porirua and Linden has become much more visible to the public, who are beginning to see just how far the project has come since we started construction and it’s an exciting time,” Justin said.
Aerial view looking South from Mackays Crossing showing current State Highway 1 to the left, the route of the Transmission Gully motorway in the centre and the new local road to the right. A short interim section has been built to create a smooth connection between the local road and the state highway until the new motorway opens.
To reduce possible confusion for road users, the traffic management layout from recent Mackays Crossing Upgrade work remains in place to direct traffic to the new road. These controls and the new road alignment between Mackays Crossing and north of Paekākāriki will stay in place until the Transmission Gully motorway opens in 2020.
With summer well and truly here the summer works programme is now underway. The next few months will see significant progress across the project’s structures with many nearing completion in the final summer of bulk earthworks.
There are several very noteworthy events coming up over the summer which mark significant milestones for the project. It is important we take a moment to recognise these and what they mean to advancing the project.
Some of the most significant changes to structures are outlined below.
With SH1 traffic moved across to the new coast road connection, our main site entrance at Paekākāriki and access for residents living east of the state highway will also move to utilise the new road built as part of the interchange in this area. This runs under the Bridge 2 flyover which has had all beams placed on it.
With this done and the highway traffic safely diverted around the west side of the project, we will get stuck into moving earth to form the embankment on the north side of Bridge 2 across the old highway road to link with the large mound of earth in the ‘pre-loaded’ area of peaty ground south of Mackays Crossing.
SH1 Mackays Crossing interim layout.
In preparation for the eventual interchange at Lanes Flat, SH58 will be moved across to its new permanent alignment in early 2019. This marks the first permanent realignment of state highways on the project, and is the most significant change for SH58 users – until the new motorway opens in 2020.
The SH58 interchange at Pauatahanui requires four separate bridges to be constructed. The main TG flyover over SH58 (Bridge 13) has thirteen 1525 millimetre deep “Super-T” beams that weigh a whopping 64 tonnes each and are put in place using a 400 tonne crane.
View more information on the upcoming roadworks at SH58 Pauatahanui
SH58 interchange interim layout.
Connecting the bridge over Cannons Creek from one side of the valley to the other is a long and slow process that will take approximately eight months to complete. By Easter 2019 the bridge will have reached across Pier 2 and be around halfway through its slow journey to the northern abutment across the creek 65 metres below.
We recently completed extensive testing and a trial launching process, which has successfully moved the first set up beams across the launch yard. The black ‘launch nose’ provides temporary support through the launching process and will be removed once the permanent beams reach the north side. As you will see at the end of the video below, the launch nose is now hanging out in front of the southern abutment over the valley below.
For more information, photos and timelapse footage of the trial launch visit www.nzta.govt.nz/tg-bridge-20
The bridge beams in November 2018 with the black launch nose assembly attached, undergoing testing and waiting for trial launching in December 2018.
Watch the timelapse of the construction and trial launch of Bridge 20 over Cannons Creek during December 2018.
With southbound SH1 traffic lanes now running over the new bridge over Collins Avenue to create a wider and safer work area between the northbound and southbound traffic lanes, the next stage of the Linden and Kenepuru interchanges is underway. As soon as the traffic was moved, we mobilised a 120 tonne crane and another 120 tonne piling rig into the median to start work on the piled foundations for Bridge 25 (the northbound flyover connection onto the Transmission Gully motorway) and Bridge 27 (the bridge across SH1 connecting the new motorway to Kenepuru Drive in Porirua).
For each bridge pile, a three metre diameter tube or ‘sleeve’ was driven around five metres into the ground and then a 2.1 metre diameter pile was bored to a depth of around 24 metres. A very large steel reinforcing cage was then lifted into the borehole by the crane, and on the same night a long funnel or “tremmi” was lowered in, and 88 cubic metres (15 truckloads) of concrete is pumped in to form the pile. This whole process took about a week, working at night, for each bridge pile.
With this foundation work recently completed, the crane and piling rig have moved out of the median, and work on the bridge columns is about to start. Over the coming weeks and months progress will be more visible to road users as the formwork and concrete columns slowly rise up from the ground. Eventually the pier heads will spread outwards above the columns, ready for beams to be placed (at night without traffic flowing underneath) over the SH1 traffic lanes. Placement of the beams is scheduled to take place before mid-2019.
Crane and piling rig in median starting their evening shift by lifting the reinforcing cage for Bridge 25 into the first pile hole.
Aerial view looking north showing both bridges that will have beams placed on them by the end of the summer programme.
Engineers look on as demolition experts dismantle the old bridge.
Saturday 3 November marked an historic milestone for commuters between Porirua and Tawa when the first of two 60-year-old SH1 overbridges was demolished to make way for the future.
Constructed side by side in the 1950s, the south and north bound Collins Avenue overbridges carried two lanes of SH1 traffic in each direction, running over Collins Avenue in Tawa.
In the future and as a result of Transmission Gully, the face of SH1 between Porirua and Tawa will look significantly different with a single six laned bridge planned as the southern tie-in connection to Transmission Gully.
To carry out this complicated change, it was recognised that construction needed to be completed in three stages, ensuring that four lanes (two in each direction) are available during peak traffic.
The first stage commenced in 2017, with the construction of a new southbound Collins Avenue overbridge (near Tawa College) and then shifting south bound traffic onto the new alignment (as outlined in a previous article).
Once traffic was shifted onto the new alignment, the project team then went about demolishing the redundant southbound Collins Avenue overbridge, recognising that a significant piece of Wellington and New Zealand roading history was being removed in the process.
While sounding like a simple feat, the work in the area has been anything but simple.
During the construction of the new southbound overbridge, the project team needed to be very careful to protect the old bridge to ensure its structure was not compromised during the build of its replacement.
On Friday 12 October, the southbound lanes of SH 1 between Porirua and Tawa were ‘switched’ onto the newly constructed lanes and new bridge. This was achieved seamlessly overnight, after many nights prior work to move road barriers, tie-in asphalt, and move and install road-edge barriers and light poles, as well as paint new line markings.
With the traffic lanes moved, the way was clear to demolish the old southbound bridge. Many months of planning went into achieving this safely and efficiently, to minimise effects on the travelling public and nearby residents in the Linden suburb.
With demolition taking place on Saturday 3 November, the night before demolition Collins Avenue had a layer of gravel and steel road plates placed on it, to protect the existing road surface and sensitive underground utility services from damage by falling concrete debris from the bridge.
On the same night two 40 tonne excavators with large hydraulic rock breaking attachments (jack hammers) were moved into the widened motorway median area between the live traffic lanes – one at each end of the bridge. A third excavator was moved under bridge. This one had hydraulic rock crushing jaws to break up the middle section of bridge that couldn’t be reached by the excavators working from the top.
Engineering ‘cross-section’ drawing showing orientation of the three excavators used to demolish the bridge. Note they had rock breaking attachments rather than the excavator buckets shown above.
By 6am on Saturday morning, Collins Avenue had been closed to through traffic, and one lane in each direction on SH1 had also been closed, as a safety precaution in case of flying rock particles from the demolition process. Even though work was programmed at the weekend to avoid the busiest weekday travel periods, one lane each way did not provide enough capacity for usual Saturday traffic volumes from late morning to early evening, so an extensive communications campaign successfully encouraged road users to avoid travelling if possible during this time. Even so, work was planned to be done as quickly as safely possible, and a team monitored traffic flows throughout the day, with a range of contingency plans available to every possible scenario to be managed.
One of these plans needed to be put into effect very soon after demolition started, when a driver sped through the area and attempted to overtake in the closed traffic lane, putting himself, his passengers, and others in danger. His car eventually came to rest inside the closed lane, with only three wheels intact. After police attended the scene, our standby tow truck and road sweeper swiftly dealt with the immobilised vehicle and debris to ensure traffic flowed freely again only a few minutes later.
Demolition of the bridge continued smoothly throughout the very heavy rain on the day, which turned out to be useful in suppressing dust. At approximately 10am we were in a position to open both northbound lanes, and make a start loading up trucks with concrete rubble using the southbound lane closure. Most of the rubble was dropped below to Collins Ave, where an empty lot next to the bridge site was used as a short-term stockpile area to quickly move rubble to, enabling us to open Collins Avenue to through traffic (after a good sweep!) by 8pm on Saturday evening. Watch a timelapse video of the operation below.
With good planning, teamwork and collaboration with the NZ Transport Agency for traffic management and communications, the demolition was completed ahead of time, incident, and with minimal disruption to road users and residents. With the redundant Collins Avenue overbridge now demolished, we have started building the middle section of the new bridge in the median area, and will go through a similar process next year to shift the northbound traffic lanes and demolish the original northbound bridge.
In the meantime, we are also busy in our new work area between the SH1 traffic lanes working on Bridge 25 – the northbound flyover connection onto the Transmission Gully motorway – and Bridge 27 – the bridge across SH1 connecting the new motorway to Kenepuru Drive in Porirua. You can read more about these above, and in next year’s newsletters and construction updates.
Constructed in the 1950s, the Collins Avenue overbridge along with the wider Johnsonville to Porirua motorway is in fact recognised as New Zealand’s first motorway.
The first section of the motorway was opened on Saturday 23 December 1950, runinng from Johnsonville in the south through to Takapu Road in the north. It was constructed as a bypass to the Old Porirua Road which saw traffic in and out of Wellington travel between Kaiwharawhara, Ngaio, Khandallah, Johnsonville, Tawa and then to Porirua Harbour.
The second section of the motorway, from Takapu Rd to Porirua and included the Collins Avenue overbridge was opened to the public in 1956. During the design phase a large interchange at Collins Avenue was planned, but due to financial constraints, the interchange option was deferred and two overbridges were constructed instead.
Very soon after the opening of the extension to Porirua, the four-laned bypass at Johnsonville was opened and remains to this day, the connection between Nauranga Gorge and the western Wellington region.
View a larger version [PDF, 1.1 MB]
Sometimes a picture is worth a thousand words.
Below are snapshots of before and after aerial images showing some of the fantastic progress that has been made this year.
On Friday 14 December we will be switching State Highway 1 over to an interim layout, using part of a new stretch of road that we are building between Paekākāriki and Mackays Crossing.
This will eventually be a local road that will run alongside the new motorway to provide a second route to and from Paekākāriki and the Centennial Highway.
Temporarily moving SH1 road users onto this new section of road will allow us to build the section of Transmission Gully that crosses over the existing SH1 without disrupting the flow of traffic. The graphic below shows where the interim road will be in relation to the existing SH1 and how Transmission Gully will eventually replace this section of road.
The Transport Agency has finished maintenance works on SH1 at Mackays Crossing but the traffic management has been left set up in preparation for our switch over to the interim road. These controls and the new alignment will stay in place in place until Transmission Gully motorway opens in 2020.
Please be aware of this change and take care if you are travelling through the area.
Read more on the interim switch of State Highway 1 at Paekākāriki and Mackays Crossing.
SH1 Mackays Crossing interim layout.
There will be a lot of work in early 2019 at the Bradey Road intersection while we work to switch State Highway 58 over to its new final alignment.
We have been consulting with the community, local businesses, and key road network operators on a range of options and timings for undertaking this work. We have developed a solution to switch the road across in early in 2019, with the Bradey Road intersection remaining much as it is now. We will then work at night over the following week to build the intersection up to its final height, which ranges up to nearly one metre above the current road in some locations, in order to raise it out of the flood plain. Temporary speed limits will be in place during the day, and there will be ‘Stop/Go’ lane closures while we undertake this work at night.
We apologise for any disruption this may cause and thank residents and local businesses for their feedback during the consultation phase. We believe this is the best compromise between the needs of local residents and commuter traffic to get this significant milestone completed.
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SH58 interchange interim layout.
Women in Construction 2018 Award recipients from left to right: Papua Taumate, Gabby Bush and Jemma Dutton.
Ensuring the employment of the best people for the job has been a key factor for the Transmission Gully Project team.
Last month the Transmission Gully Project hit the massive milestone of 5 million work-hours to date with a whopping 170,000 hours in November alone. This is the equivalent of 950 full time workers, although exact numbers change throughout the month depending on a range of subcontracted and weather-dependent tasks. The work is completed by an ever-changing mix of employees, contractors and sub-contractors and as we head into the final summer of bulk earthworks these numbers will certainly increase.
With a project the size of Transmission Gully Motorway, having a great team is vital to the success of the construction. Very early in the project it was recognised that the local job market would be unable to fulfil the number and type of skilled roles required to complete the work, and has meant the recruitment of skilled staff from around the globe.
At present, as well as New Zealanders, the project employs staff from a diverse array of countries including: Australia, England, Scotland, Wales, Ireland, France, Belgium, Germany, Brazil, South Africa, the Philippines, New Caledonia, Columbia, Fiji and Sri Lanka. This medley of nationalities fills skilled roles across the board from steel tying to project leadership, environmental engineering to support staff. The project also draws from the pool of expertise offered by both the Construction Joint Venture partners’ parent companies, Vinci (which is French) and CIMIC (which is Spanish).
Employment and upskilling of our local workforce has been an important target for the project from the outset. The construction team works closely with Ministry of Social Development and Industry Training Organisation Connexis to recruit and upskill local labour and also works with universities to provide summer internships and graduate placements, which give the recipients invaluable “on the job” work experience opportunities.
There has also been a focus on promoting and improving female participation within the group and a commitment to achieve gender equity, including pay equity. The aim is to ensure that a minimum of 30% of the team are women – with additional targets of:
Justin Redelinghuys, Transmission Gully Construction Project Director, is particularly proud that project team members were recognised at the 2018 Women in Construction Awards. “This is an outstanding achievement and we are privileged to have such talent within our project team.”
Read the story on the 2018 Women in Construction Awards
The community team attended the Pauatahanui School's annual Lamb and Calf Day.
Transmission Gully touches many communities along its route and we try to get involved where we can, particularly with schools.
Pauatahanui School is right at the heart of our project and over the last few years we have been able to support the school in a number of ways. Every year we have a stand at their annual fundraiser, Lamb and Calf Day, and this year we helped with the traffic management for the event, which affects a state highway and is a big task for the parent volunteers. We also donated over 500 plants to the "Potty Planters" plant sale, another of the school's key fundraising initiatives. In previous years we have helped out by clearing some old trees and extending their playground area.
Another of our nearby schools is Linden School. Right beside the Collins Ave over bridge, this school is also right in the heart of the action. We have been able to help with some of their fundraising events and assisted with the cost of building a new playground. Our Community Liaison team gives talks and presentations to many other local schools as well. We always enjoy talking to the kids and answering their thought-provoking questions, such as whether we found any unicorns in Battle Hill!
Local events such as Spring Into Tawa, Creekfest, Eat Drink and Be Crafty, and Battle Hill Farm Park Day as well as school galas provide a great opportunity for the TG team to meet with the community and answer queries about the project. We try to get the mobile information centre along to these events where practical as it’s always a popular source of project information.
On Monday 10 December, a short three minute story on Transmission Gully aired on Seven Sharp. Take a look at the coverage including some exclusive behind-the-scenes footage.
(external link)
Seven Sharp's Arrun Soma takes a sneak peak at Transmission Gully.
Mobile visitor centre in Civic Square
Have you stopped in at the Transmission Gully Project mobile visitor centre currently located at Civic Square yet?
If not, you’d better be quick, as the mobile visitor centre will be picked up at the end of the month and transported to Battle Hill Farm Forest Park.
It will be there for the next few months, so that visitors to the park and the great events held there over the summer (including the park open day and Eat, Drink & Be Crafty) can view information about the Transmission Gully motorway project, together with details of the Waitangirua and Whitby Link Roads which are being built for the Porirua City Council at the same time as the new motorway.
Outside of festival weekends, the mobile Transmission Gully visitor centre is open to the public Monday to Friday from 10am until 4pm.
