The NZ Transport Agency continues to make excellent progress benching the Manawatu Gorge slip. Crews are working at both the top and bottom of the site, the first bench is finished and a second one is underway. And despite even more rain this week, 12,000 cubic meters of debris has been cleared from the bottom of the slip.
State highways manager David McGonigal says that while it’s encouraging to see the benches take form, conditions on the site are still extremely challenging.
“As we move further down the slip, we’ve gone from digging through clay, river gravel and sand to hitting some pretty solid rock. Although this means that less debris will be falling down into the river, contending with boulders up to eight meters in diameter presents its own set of challenges.
“Safety remains paramount, and we must ensure that the crew at the bottom is out of the way and well protected as these bigger rocks come down.”
The NZTA has also made some refinements to the design of the benches. Mr McGonigal says that while the original plan was to slope the benches towards the Ashhurst end of the slip, engineers have now decided to shape them towards Woodville. Mr McGonigal says that this decision was made for two reasons.
“We are constantly reviewing the bench design, to ensure the right amount of material can be removed and any water run-off managed safely. The Woodville end has a stable sandstone outcrop that will act as a flume and take the water safely down to the river below. In addition, this approach will reduce the number of benches by one, thus speeding up the operation.”
The NZTA also continues to work closely with Horizons Regional Council around the condition of the river, and the delta that formed last week is now washing away. Mr McGonigal says that the road crew is removing as much material as possible from the side of the slip and the benching crew is directing as much material as possible to the ‘hole’ they’ve created at the bottom. This has significantly reduced the amount of debris flowing into the river. Over the next few weeks, crews will attempt to “turn” the slip face, so that the rocks and dirt come straight down to the road. This will reduce the amount of material going into the river even further.
Mr McGonigal says that work to improve the alternate roads is also continuing, with a heightened maintenance programme on throughout the holiday period. “We’ve sealed the first half of the Woodlands Road and have also widened the second half. We will reseal this portion after the holiday period, with work expected to start on 4 January.
“We’ve finished the line marking and priority change at the Woodlands/Oxford Road intersection. Tararua District Council have reopened Oxford Road and we have had some truckies sneaking through the chicane there. We’ve moved the barriers closer together to make this difficult for larger vehicles.
“We’ve also re-marked the centre line on Saddle Road and installed a traffic island at the SH3/Woodlands Intersection to reinforce the Give Way.”
The NZTA says drivers should allow more time for the travel. Diversions may add up to an extra 15 minutes on to journey times.
Mr McGonigal thanks motorists and locals for their ongoing patience and understanding as the gorge enters its fourth month of closure, and says that the NZTA will continue to make reopening the road safely its highest priority.
“We want this slip cleared as much as everyone else does, and we’re doing everything we can to make that happen,” he says.
For information about the Gorge closure, including video of the site and an easy to understand diagram of the benching process, please visit the NZTA’s dedicated gorge web page: www.nzta.govt.nz/manawatu-gorge.