The NZ Transport Agency says the Manawatu Gorge is on track to re-open in a little over a month, with crews continuing to work 24/7 and the rebuilding of the highway remaining well on track for an early September opening.
NZTA Palmerston North state highways manager David McGonigal says despite a fair amount of rain this week, contractors have worked around the clock where possible, and the rebuild was advancing well . Notably, the 85m long retaining wall that will replace a destroyed half-bridge is taking shape quickly.
"From week to week, the troops are putting in the hard yards, and they're making real and visible progress, every day and every night."
Mr McGonigal says the NZTA is rebuilding a number of different structures simultaneously.
The main bridge, at the Woodville end (Bridge 8 in the attached annotated aerial image), is being completely rebuilt into a brand new three span bridge 60m in length.
"This is the big job, and the structure of the bridge is largely complete, and now we just need to cure the concrete and anchor the bridge to the rockface."
Towards Ashhurst, a destroyed half-bridge (Half Bridge 7) is being replaced with a new retaining wall to secure the new road in place. The retaining wall is 6 metres high (about the height of a two story building) and 85m long.
Mr McGonigal says this work involves a large amount of drilling to put in place the piles that will hold the structure, and thus the highway, securely in place. This work is progressing well, with sixteen piles drilled already and the wall visibly taking shape.
"On the far Ashhurst end, the broken bridge beams on the half-bridge (Section 3.1) have been replaced and the structure is as good as new. Finally, on the far Woodville end (Half Bridge 9), the existing half-bridge hasn't been damaged but bridge beams and piles are being constructed to 'tie in' the existing highway to the big bridge we're building."
Mr McGonigal says the short timeframe the crews have achieved in planning, designing and rebuilding the structures is remarkable.
"To plan and build such a complex suite of structures in a tight natural environment is truly outstanding, and probably without comparable precedent in New Zealand. The team has really pulled out all the stops and they'll all deserve a holiday when the job is done."
Mr McGonigal says contractors are continuing to look after the alternative routes, and reminds drivers to take care in winter weather on the Saddle Road, and in particular to watch out for ice and slippery conditions.