Note: this cache is not available from the motorway - you must either walk or cycle to it along the purpose built pathway. Bring your own pen.
Hidden just north of the mighty Parahaki Bridge lies a quieter, lesser-known structure — but one with a story deeply rooted in the land it crosses.
Bridge 3 — also known as the Eco-Viaduct — spans 305 metres across an ecologically sensitive wetland in the Manawatū. It’s not just a feat of engineering, but a commitment to doing things differently: to build a major piece of infrastructure while treading gently on the landscape.
When work began here, engineers faced more than just tough ground and high winds. The land beneath the wetland was soaked and stubborn — with unexpected groundwater pressures halting construction for months. And beneath that, a fault line added seismic risk to the list of challenges. But the design team met those trials head-on, drawing on advanced seismic modelling, using weathering steel to reduce maintenance, and anchoring the bridge with integral piers and ductile concrete that could sway and flex with the earth.
But BR03’s legacy isn’t only in steel and concrete — it’s in the life returning beneath it.
This viaduct was designed not just to pass over the wetland — but to protect it. The bridge allowed the highway to rise above, keeping machinery and heavy traffic away from the delicate ecosystems below. What had once been a struggling landscape is now in the middle of transformation. Over 1.8 million native plants have been planted across the project area. Swamp maire, raupō, and wetland sedges are returning. Streams have been restored across 28 km, and pest control is helping protect 300 hectares of forest habitat nearby.
You’re standing at the edge of that change.
The shared-use path here connects people with place. Take a moment to look down and around — what you see under BR03 is more than mud and water. It’s a landscape being healed, one native plant at a time.
To find the cache, you'll need to observe your surroundings — including signs of both engineering and ecology. The “Western Tracks” are still under construction, but once complete, they’ll connect walkers and cyclists all the way to Saddle Road, passing through impressive natural bush and rehabilitated farmland. Bring your curiosity — and maybe a pair of binoculars for spotting birds enjoying their newly restored home.
The Image below shows the underside of BR03 prior to the bridge deck being installed. Observe the large steel beams used to hold the deck.
