Kia ora and welcome to the July 2018 update from the Transmission Gully team.
Beams being lifted into place at the SH58 motorway overbridge (Bridge 13) at Lanes Flat.
With the completion of retaining walls and abutments, and the placement of bridge beams and barriers, many of our structures are really starting to look more like the finished product. The traffic switches at both Mackays Crossing and Linden are getting much closer as work continues in both areas. Make sure you keep an eye on our newsletters so you know what to expect.
Here’s what’s been happening across the Transmission Gully project in the last month, and what’s coming up.
In the north, we are busy carrying out preparatory works for temporarily switching State Highway 1 over to join part of the new stretch of local road to Paekākāriki and the coast. This will happen in the next few months and be in place for around two years. It is required to keep traffic flowing freely while we build the motorway across the existing highway. We have completed the earthworks for where this section of new road will connect into SH1 tie-ins and have started drainage work and the basecourse (gravel) layers for the new road, as shown on the images below. We have also started work to move our site entrance ready for the changes in road layout.
Over the last few weeks, the Transport Agency has been carrying out maintenance works on SH1 between Paekākāriki and Mackays Crossing. This is due for completion in August but some of the traffic management will remain in place until the switch over to the new coastal road. This is for both staff safety during our works and consistency for road users. Next month we will have graphics and information about the changes to the road layout and what you can expect. For more information about the maintenance work please go to the Wellington region maintenance programme webpage.
Looking north towards Mackays Crossing showing progress on new road to Paekākāriki and the coast.
Good progress is being made on the motorway overbridge north of Paekākāriki (Bridge 2) and it is really starting to take shape. This is where the traffic diversion will connect back into the State Highway. A new local road roundabout being built on the other side of Bridge 2 is clearly visible.
On each side of the Wainui Saddle, we have moved into our winter works programme, with a significant reduction in bulk earthworks and a focus on stream diversions. South of the Saddle, water will be directed into another section of the diverted Horokiri Stream in August, while on the northern side, great progress continues to be made in the Te Puka Stream diversion with several sections now complete.
The Material Stabilised Earth (MSE) walls for Bridge 4 over the Horokiri Stream are over 70% complete, and the bridge is really taking shape. This bridge is over one of the diverted sections of the Horokiri Stream and you can see the rip rap edge of the diversion at the base of the walls in the photo below.
Wainui Saddle construction site, looking south down the Horokiri Valley.
One completed section of the diverted Te Puka Stream with water now flowing. Fish will be returned to the channel once the whole diversion has been completed and the banks planted.
Rip rap being placed in a section of the Te Puka stream diversion. Rip rap refers to the large rocks being placed to ensure the new stream diversion doesn’t erode.
MSE walls at Bridge 4 over the Horokiri Stream are well underway and the rip rap edge of the stream channel can be seen at the base.
Work continues on one of several diversions of the Horokiri Stream. The bright green areas protect the slopes from erosion in winter and contain grass seed to revegetate earthworked areas.
Installation of the barriers at another of the bridges of the Horokiri Stream (Bridge 6) is complete and finishing work to connect the barriers to each other is underway.
We have also implemented our winter works programme from Battle Hill south towards SH58 and the key focus now is the bridges and large culverts through this area rather than bulk earthworks.
A crane lifts barriers into place on Bridge 6.
At the public underpass at Battle Hill, with earthworks complete ready to start placing the road pavement layers this summer.
Beams being lifted into place at Bridge 13.
At Lanes Flat, the SH58 interchange is shaping up nicely with the beams already in place at the SH58 motorway overbridge (Bridge 13).
Aerial view of SH58 Interchange at Lanes Flat.
The crane is at the bridge for the northbound offramp (Br14) to place beams over the Pauatahanui Stream diversion. The roundabout connecting the on and off ramps to the new section of SH58 is visible behind. SH58 traffic will be switched onto this new section to run under the motorway overbridge (Bridge 13 – visible in the centre of the image) later this year.
South of SH58, great progress has been made on the James Cook Interchange which will link Waitangirua and Whitby to Transmission Gully. It is now possible to get a sense of the layout of the road and the scale of the earthworks we are carrying out at this site.
Earthworks at the James Cook Interchange show the scale of the embankments for the motorway flyover (Bridge 16).
An aerial view looking south from the James Cook Interchange. The cuts just north of Cannons Creek are visible in the far distance.
Work on Bridge 20 at Cannons Creek continues to progress well. At Pier 1 we are assembling the reinforced column cage in a cradle to help safely lift it into place. There is a huge amount of steel reinforcing in all the bridges to ensure they will be able to withstand large earthquakes.
At Pier 2 we have completed the first column pour and are preparing for the next reinforced cage to be lifted into place.
In August, the special steel ‘nose’ that will be used to support the beams when they are launched across the Cannons Creek valley is expected to arrive on site.
The reinforced steel column cage for Pier 1 (on the north side of the creek) at the Cannons Creek Bridge.
Preparing Pier 2 (which will support the bridge from the south side of the creek) for the next cage to be installed.
Bridge 20 beams waiting at the launch yard at the southern abutment. Space has been left at the front of the beams for the launch nose to be attached.
In the southern zone, we are very focussed on preparation for the September traffic switch which will move the southbound traffic over from the existing Collins Ave overbridge to the first section of the new overbridge (Bridge 26). The new Bridge 26 is around two metres higher than the old bridge and the team is building the approach embankments either side of the new bridge to tie into the existing lanes. Once the traffic has been switched off the old bridge onto the new one, we will demolish the southbound section of the old bridge and begin construction of the second section of new bridge in a worksite between the north and south bound lanes of SH1.
As part of this work, in August we will be making the road wider on each side of the motorway south of Mungavin Interchange to just past Tawa College. This allows for the demolition of the old Collins Ave overbridge and also provides a larger working area in the central median for building the central columns for Bridges 25 (the northbound ramp onto Transmission Gully) and 27 (the Kenepuru Link Road over SH1).
The majority of this realignment work will be done at night to minimise disruption from the necessary lane closures. We apologise to residents and motorists for any disruption this may cause and ask that you take care when driving through this area as there will be changes in road surface and temporary speed restrictions in place at times.
Once the lanes are realigned, daytime southbound speed limits will also be reduced to 70kph to ensure driver safety through areas where the concrete barriers may temporarily affect lines of sight. The reduced speeds are also vital for the safety of our teams working alongside the live traffic lanes. Please pay close attention to the signage and keep to the posted speed limits.
A traffic switch in September will move southbound traffic over from the existing Collins Ave overbridge to the first section of the new overbridge (Bridge 26).
As part of this work, in August we will be making the road wider on each side of the motorway south of Mungavin Interchange to just past Tawa College.
Young Kanuka seedlings waiting to be planted out in the northern zone.
While we planted some small areas last year, this season we are really ramping up our extensive planting programme. By the time the motorway opens, we will have planted in excess of two million plants. Some are for landscaping purposes, but most are planted in ecological areas to mitigate the effects of construction on terrestrial, marine, and freshwater habitats.
We have started taking delivery of the first batches of the specifically propagated plants and will have more information in coming months about how planting is progressing.
Tom Puxley, CPB HEB JV Project Engineer onsite at Transmission Gully.
Listen to regular radio interviews with our team to hear more about what they're working on for the project.
In the latest radio interview, Tom Puxley, CPB HEB JV Project Engineer talks about seismic resilience design factors and the building of Bridge 26 at Collins Avenue in Linden.
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We hope you enjoy reading these updates, and we’d love to hear from you. If you have any questions, comments or story suggestions, you can email them to info@tg.co.nz.
