SH1 Papakura to Drury

Construction update

6 June 2024

Construction update | He pānui

Kia ora

We are now well into the 'winter works' season which brings with it cooler temperatures, less daylight hours and increased rainfall.  While winter weather can impact on our construction progress, the team has continued to make good strides.

For the safety of both construction crews and SH1 motorists, a decent portion of the work over the last month has been carried out at night with either full or single lane motorway closures in place.  Last week and this week, our focus has been on installing new stormwater box culverts in the central median of the motorway.  Later this month, we look forward to finishing the central median culvert works and moving onto the next (and final) stage of culvert works – read on for more details.

Our Beach Road crew is also working at night, completing the pedestrian and cycle path on the southern side of the road approaching the motorway overbridge.  The existing traffic islands on the road are also being removed one at a time and then new islands will be built in their new locations.  Pavement construction also continues north of the Papakura Interchange and slip-form safety barrier works are nearing completion.

We are committed to keeping our community and stakeholders informed about the project.  Last month, over 150 visitors attended our second community information day for the year.

A box culvert trench in the central median of the motorway.

Stormwater culverts | Ngā wai āwhā karawata

As part of the SH1 Papakura to Drury project, we are upgrading three stormwater culverts running across and under the motorway.  Previously, untreated stormwater runoff flowed directly from the motorway through these culverts, and into waterways flowing into the Manukau Harbour.  The size of the culverts also contributed to flooding issues on the eastern side of the motorway.  To address both issues, we're installing three new and larger stormwater box culverts under the motorway, along with planting native vegetation in swale drains beside the motorway.  These swales will capture and filter stormwater from the motorway before it enters the new box culverts.

The project team has already installed the eastern and western sections of the three box culverts and we're now installing the central section in the middle of the motorway.

Here's a closer look at the impressive scale of the stormwater culvert works:

• Material removal: We have removed a substantial 3,000 cubic metres (equivalent to around 5,400 tonnes) of material to make way for the culverts.  Note the size of the man vs the depth of the trench in the photo above!
   
• Temporary supports: A total of 510 temporary steel sheet piles were installed to ensure safety and ground stability during construction.  These supports are then removed when each section of work is completed.
   
• Foundation and backfill: Once the excavation is complete, we use 3,200 tonnes of aggregate to create a solid foundation for the culverts. After the box culvert units are lifted into place (see photo below), the excavation is backfilled to secure them in place.
   
• Concrete construction: 1,312 tonnes of concrete was used to fabricate the box culvert units.

Once completed and in use, these box culverts will greatly improve drainage and stormwater management in this area of the motorway.  Between all three culverts, a total of 22,400 litres of water can be carried at peak flow.

Are you curious about the size of the box culverts?  Each precast unit measures between 3m and 4.5m (metres) wide, 2.6m and 3m (metres) long, and 1.8m and 1.9m (metres) high.

A total of 18 units will be installed to form the northern-most culvert (south of Papakura Interchange), 16 units at the 'middle' culvert, and 17 units at the southern-most culvert (just north of Park Estate Road overbridge).  A powerful 250-tonne crane is used to precisely position these massive units in place.

Box culvert units being lifted into place at night.

A slip-form paver machine slip forming concrete safety barriers at night.

Safety barriers | Ngā ārai haumaru

Last month, our crew finished the majority of the slip-form concrete safety barriers needed for Stage 1A of the project. This translates to an impressive 6.4 kilometres of concrete barriers installed using a specialized "offset slip-form paver" since the beginning of the project.

To achieve this feat, we strategically conducted all slip-form barrier work at night during planned motorway closures. This ensured a consistent and timely supply of concrete from our local Drury supplier as concrete trucks did not get stuck in traffic. Maintaining the concrete's optimal mixture (determined by a 'slump test') is vital before feeding it into the slip-form paver, and nighttime delivery helped avoid any delays or compromises in concrete quality.

With just 300 metres remaining, we expect to complete all slip-form barrier works for Stage 1A later this month, weather permitting. This is a significant milestone towards the completion of this part of the project.

A great turnout at the recent community information day.

Meeting the community | Hui ā hapori

On Saturday 18 May, the Papakura to Drury project team hosted our second community information day of the year at Drury Hall.  Over 150 people attended the event to learn more about ongoing construction and future plans for the area.  In addition to our project team, representatives from several other South Auckland projects were present including from KiwiRail, NZTA and Auckland Transport.

Meeting face to face is a great opportunity for visitors to ask questions and learn directly from the project teams doing the work.  Here are some of the most common inquiries about the SH1 Papakura to Drury project:

• When will the current stage (Stage 1A) be completed?  Completion is scheduled for late August/September 2024, with final asphalting planned for October/November when the weather is warmer.
   
• When will the next stage (Stage 1B1) begin?  Construction for Stage 1B1 is scheduled to begin later this year.  Stage 1B1 includes completely rebuilding and relocating Drury Interchange across to the east; replacing the two Bremner Road bridges (over SH1 and Ngaakooroa Stream); signalising the SH22/Victoria Street/Mercer Street intersection; and improving vehicle and pedestrian access on Great South Road underneath the interchange.
   
• Will there be new on/off ramps at Park Estate Road overbridge?  Due to its proximity to Papakura Interchange, for safety reasons no new motorway ramps will be built at Park Estate Road overbridge.
   
• What's happening in the middle of the motorway? The current work in the central median of the motorway involves installing three new stormwater box culverts to improve drainage (refer stormwater culvert story above).

Mark your calendars for our next community information day on Saturday 17 August 2024.  If you have any questions in the meantime about the Papakura to Drury project, feel free to contact us by replying to this newsletter or using our other contacts as listed in the "Contact Us" section below.

Latest photos from site | Ngā pikitia

We are working across the site, with lots of pavement and asphalt works; and installing stormwater box culverts.

Looking ahead | E haere ake nei

During the coming months, our project works include:

• Finishing works on Beach Road
• Installing final box culvert sections on the southbound side of the motorway
• Final surfacing work (asphalting) on both northbound and southbound sides of the motorway, starting in October/November.

Contact us | Whakapā mai

For further information regarding the project please contact our team:

P: 0800 796 796 or text 027 703 5284 - for construction-related queries
P: 0800 741 722 - for general project queries
E: p2b@nzta.govt.nz
W: www.nzta.govt.nz/p2b

You can also visit the Papakura to Drury project site office during normal business hours (weekdays 8am-5pm) at 25 Tegal Road, Drury.