Manawatu Cycle Bridge ‘He Ara Kotahi’

LOCATION Palmerston North, ‘He Ara Kotahi’, shared pathway   PRINCIPAL Palmerston North City Council   PROJECT DATES Jan 2017 to July 2019

Construction of a new pedestrian and cycle bridge across the Manawatu River, spanning approximately 195m and width of 4.5m. The bridge construction involves earthworks, piling, and alterations to the stop banks with temporary diversion of the river to build the bridge piers.

Structure: The four span bridge design concept is based on the karaka tree falling across the river forming a bridge. This makes reference to the nearby karaka grove and its significance to Rangitāne. The northern bank compliments the Esplanade and nearby reserves with plant beds and a tall art installation representing a ‘pou’ or sentry. The bridge itself features 3 viewing decks and posts carved inwards and outwards representing the bough, branches, roots and base of the tree.  The new pedestrian and cycle bridge spans approximately 195m with a width of 4.5m. The piers stand 7.5 metres above the river and are anchored 22.5m underground.

The bridge construction is diverse in that it involves earthworks, piling, temporary diversion of the river, steel superstructure, precast concrete deck panels, insitu concrete works, timber, drainage, new/relocated services, safety barriers and landscaping. CSL have closely managed all aspects of construction, within our ISO 9001:2015 Quality Management System (QMS).

Health & Safety: Site specific Health & Safety Management Plan was implemented and observed in accordance with the company’s secondary level requirements for ACC WSMP. Zero LTIs or serious incidents have incurred. This project highlights the standards CS use to minimise key high-risk areas such as working at heights; crane use and working around live plant.

Environmental Management:  Construction involves working in a highly sensitive natural environment over a river prone to significant flood events.  A temporary concrete slab bridge over the stream was built during winter to enable work to continue on the main structure without disturbing the aquatic life.

He Ara Kotahi is a partnership between Horizons Regional Council, Massey University, Palmerston North City Council, New Zealand Army at Linto, NZTA and Rangitāne.  The close consultation with all stakeholders involved demonstrates CSL’s ability to work in a very controlled environment with many stakeholders while satisfying each of their differing requirements.

Earthworks:  Low to moderate earthworks were required. Works include progressive stripping of 1200m³ topsoil and vegetation, removing the surface cover while protecting the exposed erodible surface.  Following stripping, placement of fill material and/or cut excavations commenced, including bridge piles, 7,500m3 of clay fill and 5000m3 of granular fill for the new bridge embankments, 4000T of rock rip rap protection, landscaping and planting. Earthworks were carried out prior to the winter season with progressive stabilisation proceeding as each section of work is completed.

Drainage:  Adequate fall provided to walkways and drainage installed underground along with sediment control measures.

Traffic Management:  A site specific Traffic Management plan was implemented, providing access for light vehicles and allowing safe manoeuvring for trucks onto site for the delivery of the 18m long bridge beams. The site is fenced with access to the existing riverside cycle path maintained up to site boundary to allow recreational use of the river side park.

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