Dairy Flat Highway safety improvement project updates Dairy Flat Highway safety improvement project updates


11 June

The construction of the roundabout on Dairy Flat Highway has made good progress lately. Traffic is controlled via the temporary traffic lights. We expect to be able to open the intersection back up to two-way traffic in mid-July, with completion still on course for late November.

Most of the road pavement has now been completed, with Coatesville-Riverhead Highway and a small portion of Dairy Flat Highway still to be completed. The final layer will be laid towards the end, once all the traffic islands have been constructed.

Dairy Flat Highway safety improvements

The fifth retaining wall on Coatesville-Riverhead Highway has been completed and the team is now constructing the sixth wall. Check out the images below

Dairy Flat Highway safety improvements

Construction of an additional reinforced wall also began construction recently, which will help ensure the road is well supported once work has been completed. This work needs to be done, after the team discovered the ground in one area was unstable, following a major slip in the 1960s.

4 May

The Dairy Flat Roundabout project has been safely closed for the duration of the Level 4 alert period.

Auckland Transport has used the time in COVID-19 Alert Level 4 to plan the return to work with a safety focused approach.

Work recommenced on 28 April 2020 on the roundabout and will progressively restart work in other areas over the following weeks and months.

The location and timing for when we start work across various parts of the construction zone depends on a number of factors including the Government alert level and ensuring that we can deliver work within health, safety and physical distancing guidelines.

Health, Safety and Physical Distancing

We would like to assure you that our teams will be following strict health, safety and physical distancing guidelines. This is to ensure the safety of our staff and the community. Each project site has developed a Health and Safety Plan based on Ministry of Health Guidance and industry best practice. At Level 3 these measures include:

  • physical distancing, compulsory PPE, hygiene practices on site entry and exit and separating teams into zones on our larger sites.
  • contractors will be required to submit return to work plans to demonstrate a safe return.
  • a full re-mobilisation and on-boarding process for each site covering COVID 19 restrictions, ensuring a staged, safe return to the projects.
  • inductions for new project staff and compulsory COVID 19 education and training will be part of ongoing site protocols whilst in a Level 2 and 3 scenarios.

The key works taking place shortly will be the continuation of retaining wall construction along Coatesville-Riverhead Highway and the western side of Dairy Flat Highway, and road pavement construction along Dairy Flat Highway.

Working hours will remain primarily during the day (7am to 7pm), with works such as road pavement asphalting being done at night.

Find out more info around our response to COVID-19.

16 March

Temporary traffic lights have been installed at the intersection of Dairy Flat Highway/Coatesville-Riverhead Highway, as teams are working hard on the safety improvements being implemented in this area. The traffic lights have been installed and only one lane of traffic can operate through the intersection while teams complete the work required.

The lights will be in place for approximately three months, until the works along Coatesville-Riverhead Highway are complete. This includes retaining walls, road pavement, kerb/channel and guardrails.

The road has been reduced to one lane as there is simply not enough room available along Coatesville-Riverhead Highway to complete these works while maintaining traffic flow in both directions.

Dairy Flat Highway is also down to a single lane on the northern approach at the moment, until construction of the southbound pavement is complete (asphalting currently planned for end of March). Once this is complete Dairy Flat Highway can be opened to traffic in both directions on the new asphalt, which will improve the situation.

Download the Stop-Go temporary road rules map (PDF 770KB)

3 March

​On the south west corner of the intersection, following on from the stormwater works they have recently been digging out areas of existing footpath/kerbing/berm in order to construct kerbing along the new alignment. This new kerbing was installed on Monday.

Dairy Flat Road looking south at the Coatesville Highway intersection.
Dairy Flat Road looking south at the Coatesville Highway intersection.

Following this they will now be constructing concrete footpath in this area and road pavement. It is expected that works on this corner will be completed by the end of March. The temporary barriers around this corner will then be removed and the footpath opened back up to pedestrians.

Following this they will get started on construction of the two new retaining walls on Coatesville-Riverhead Hwy (northern side).

All of the retaining walls along the eastern side of the site have been completed, as well as the new kerbing and some of the crash barriers.

Dairy Flat Highway at the Coatesville Highway intersection looking North.
Dairy Flat Highway looking north at the Coatesville Highway intersection.

Look out for the March newsletter for more information.

3 February

Green Road

At the time of consultation, the Dairy Flat safety improvements project proposed widening the bridge just north of the intersection of Dairy Flat Highway and Green Road and adding a right turn bay.

Having investigated the proposals further, Green Road intersection improvements will be removed from the schedule of works at this time. Further investigation has found that it is not viable for us to widen the bridge. Doing so may encourage increased speeds and therefore would not deliver the safety benefits required for the overall project.

We will however continue to investigate whether alternative improvements can be made to the intersection and we will re-consult with the community if a solution is found.

Dairy Flat Median Barrier (Potter Road)

We proposed to construct a median barrier in the location of the current southbound passing lanes to the north of the intersection with Potter Road.

This was to address concerns from the community and evidence of head on collisions at the S-bend location of the passing lanes caused by loss of control at the bends.

The design has been completed but there remains an outstanding issue relating to the use of the corridor by over-dimensional vehicles and the key role that Dairy Flat Highway plays in the transit of over-dimensions loads to the north.

We have previously consulted the Heavy Haulage Association (HHA) regarding the proposals but will require further engagement around the mitigation required to retain over-dimensional trips along Dairy Flat Highway if median barrier were implemented. Discussions are ongoing


9 December

Dairy Flat Highway/Coatesville-Riverhead Highway roundabout update

We originally mentioned that we were aiming for this project to be completed by mid-2020, however, due to unstable ground conditions, work has been delayed.

Construction of the roundabout is expected to be completed in September 2020:

  • Three of the seven retaining walls have been built. Unfortunately, during construction of one of the retaining walls on the western side of Dairy Flat Highway, our contractors discovered that ground conditions were softer than expected.
  • Investigations found evidence of a historic landslide dating back to the 1950s. As a result, work stopped so further investigations could be carried out.
  • Boreholes were used to determine the extent of the landslide and based on what was found it was agreed that the current design for this retaining wall is not suitable as the ground is too soft.
  • An alternative design of the retaining wall has been developed which will strengthen the area, preventing the occurrence of further landslides at this location.
  • We are now aiming to complete the roundabout in September 2020.

1 October

Construction of the new Dairy Flat Highway/Coatesville-Riverhead Highway intersection roundabout is well under way now, along with other improvements in the area including safety barriers.
Over the coming weeks Kahikatea Road intersection improvements will start, which will also include threshold treatments which is the red surfacing applied to roads to let drivers know there is a change in road environment.

Dairy Flat Highway/Coatesville-Riverhead Highway roundabout

Three retaining walls are currently in different stages of construction, and stormwater work has started with the installation of pipes and manholes where one of the rain gardens will be installed. There have been some delays to construction due to lizard protection requirements. As part of the resource consent requirements for this project, when we carry out vegetation clearance work we need to have a herpetologist on site to recognise and relocate any protected lizards found. The cooler weather has also meant they have not been able to do this since lizards are not active during cold weather. To date, no protected lizards have been found.

Workers working on one of the retaining walls
One of the new retaining walls that will help to accommodate the new roundabout.


17 August

Temporary speed limit reduction at Dairy Flat Highway and Coatesville-Riverhead Highway intersection

Auckland Transport is working on a number of safety improvements for Dairy Flat Highway, part of these safety improvements includes a speed reduction from 80km/h to 60km/h at the Dairy Flat Highway and Coatesville-Riverhead Highway intersection. There are also new flexi posts and additional speed limit signage in place.

Dairy Flat Highway map speed reduction

The reduced speed limit was implemented in early July 2018, and the speed limit will remain at 60km/h until construction starts on the wider safety improvements in the 2018/2019 summer.