Contractor Project

First expressway project to restart

Work on the Peka Peka north of Otaki Expressway (PP2O) was the first big roading project to restart after the lockdown and work is now pushing ahead. Richard Silcock reports.

The PP2O Expressway (1) north of Wellington was the first major road project to restart physical works after Covid-19 level-2 was reached on 14 May. Like all other infrastructure projects around the country work was shut down on March 25 once level-4 of the pandemic was announced by the Government.

Completion date for this four-lane, 13 kilometre expressway that will join the Kapiti Expressway at Peka Peka has, however, been delayed for a number of additional reasons.

These include, says project director Chris Hunt (2), the Transport Agency’s decision to include a joint walk/cycleway and bridle path, adjacent to the expressway, and its specification modification for the type of paving from granular paving to deep lift structural asphalt. All of which were not included in the original specifications and design.

“There was also the shutdown of physical works as a result of the Covid-19 lockdowns at levels 3 and 4,” says Chris.

“The shared walk/cycleway will form part of the New Zealand Cycle Trail that is being led by MBIE and NZTA. It will run almost the entire length of the expressway and has required additional consents and design work before construction could commence (3).

“This also included widening the Otaki River Bridge by two and a half metres to accommodate it.

“The Covid-19 lockdown was regrettable in terms of maintaining our project schedule, but we fully support the reasons for it – helping to keep New Zealanders, and our team working on this project, safe during the weeks of uncertainty as the number of virus cases increased throughout the country.

“The lockdown dramatically reduced our work hours with only 350 man-hours recorded this April as against over 40,000 man-hours in April last year.

“There have also been some aggregate and concrete supply issues, with local quarries unable to meet demand for specific grade aggregate due to restricted hours as a result of the lockdown.”

Despite the project now being back up to speed and pushing ahead with a full complement of nearly 300 staff, these issues, and the fact that winter precludes any major earthworks, Contractor estimates a further 12 to 15 months will be required to complete the project, taking it to mid or late 2021.

Since I visited the project in April last year (refer Contractor, May 2019), the new railway realignment just north of Otaki has been completed and is now operational. All nine bridges are either completed or nearing completion, with the Otaki River Bridge only requiring safety barriers.

The two-span, steel box girder bridge at Te Horo, which crosses both SH1 and the main trunk railway line, was completed prior to lockdown. The largest 107 tonne steel beams were lifted into place by a giant 400 tonne crane over three nights, necessitating the closure for a period of both the highway and the railway line.

At the southern (Peka Peka) end of the project, considerable earthworks have seen preload coming off and the carriageway graded.

“This area, between Peka Peka and Mary Crest, was substantially peat bog, so a considerable amount of preloading, excavation and drainage was required over several years,” says Chris.

“We have completed the reinforced earth wall on the eastern façade of bridge nine near Mary Crest and are now building the western façade, abutments and approaches. This bridge will take the expressway up and over the railway line, skewed at an angle and will provide for a clearance of five metres. It is 98 metres long.

“Earthworks have continued along the straight south of the Otaki River with several shallow cuttings at the northern end and a number of local roads have been realigned or bridged to allow for the expressway.”

Pavement construction has also started along this section of the expressway. This comprises a cement modified sub-base covered with an AC deep-lift asphalt to a depth of 175 millimetres, with epoxy modified open-graded porous asphalt (EMOGPA) laid on top.

“While this is more expensive than traditional granular paving, it has a longer life, performs far better under heavy traffic conditions and requires less maintenance,” says Chris.

“EMOGPA also provides a smoother surface than chip-seal with a subsequent reduction in tyre noise and wear.”(4)

Some 57 hectares along the length, and adjacent to the expressway, is being re-established with wetlands and native plantings, replicating the surrounding area.

Alice Naylor, environmental manager for the project, says although the expressway construction created very little disturbance to the surrounding land and wildlife habitats, they are rehabilitating or establishing new ecological areas where this could not be avoided.

“We are compensating for lost biodiversity by mitigation planting to offset any impacts construction work may have caused,” she says.

“Lizards, silk worms and eels are also being relocated as an ongoing activity and during the breeding season of native dotterels near the Otaki River Bridge, construction work was minimised.”

While the existing expressway from Paekakariki to Peka Peka is referred to as the Kapiti Expressway, there has been no formal decision on a name for the PP2O section.

A further extension from Otaki to north of Levin has recently been confirmed by Government as part of its New Zealand wide $15 billion plus infrastructure upgrade programme.

This follows extensive lobbying by local community representatives and the National Party.

The design and plans for the exact alignment have yet to be finalised, however I  understand physical works are expected to commence in 2025, five years earlier than previously predicted.

Footnotes:

  1. Construction, which commenced in December 2017, is being undertaken in an 80/20 split joint venture by Fletcher Infrastructure and Higgins Contractors who are carrying out the construction, planning, infrastructure and civil work. Goodman Contractors is providing most of the earthworks and Brian Perry Civil the bridge piling. Beca is the lead designer and WSP is the Transport Agency’s principal project advisor/consultant.
  2. Chris Hunt took over as Project Director for PP2O from Andy Goldie in April this year following the latter’s move to another project.
  3. When completed the shared pathway will provide10 kilometres of safe trail separated from the traffic on the 100kph expressway. It will comprise a three metre wide AP20 seal path/cycleway and a metre wide grassed bridle strip.
  4. This method costs approximately $190 per square metre to lay by comparison to chip-seal which is around $50 per square metre.

 

Related posts

Don’t try this on the motorway

Contrafed PUblishing

Parting words from Jeremy Sole- a final column

Contrafed PUblishing

Crushing big time

Contrafed PUblishing