The NZ Transport Agency says that it is aiming to reopen State Highway 3 through the Manawatu Gorge by the end of May, although full two way unrestricted operation is still likely to be around four months away.
NZTA state highways manager David McGonigal says an inspection this week by bridge specialists has shown that the bridges along the affected span are severely damaged and will have to be completely rebuilt. Rebuilding the bridges is likely to take four months to complete.
However, Mr McGonigal says the NZTA will soon be able to reopen the gorge road to one lane of traffic, open in one direction only during the day (from Woodville) and both directions at night, meaning motorists will soon be able to use the key highway route through the gorge, which has been closed continuously since last August.
Work on the bridges during the day will mean the gorge will only be open to vehicles with single lane operation. Current plans are to open to traffic in the southwest direction (from Woodville towards Ashhurst). Vehicles travelling northeast (from Ashhurst towards Woodville) will need to continue to use the Saddle Road during the day until the bridges are rebuilt. This arrangement allows for the most efficient traffic flow and the minimisation of delays where SH3 and local roads meet at Ashhurst and Woodville.
At night, the gorge will be open to traffic travelling in both directions. These plans are being discussed with user groups and local stakeholders this week, to determine and refine the most effective one-way daytime arrangements.
Mr McGonigal says this partial reopening is strictly on a 'weather permitting' basis, and the road will be closed if there are any concerns about the highway's stability or safety.
"The team have done a phenomenal job in recent weeks removing the largest pile of dirt we've ever seen on our highway network, and while there's still plenty of work to go, having the gorge reopened to one lane will be a tremendous milestone.
"While we'll only be able to safely allow traffic in one direction during the day when demand is highest, we expect to be able to accommodate traffic in both directions at night when traffic volumes are considerably lower. This will carry significant economic benefits, as a large amount of freight is transported at night, and it will also be safer for everyone. It also means the people of Ashhurst will finally be able to get a quiet night's sleep, which is the least they deserve after patiently bearing with us for the last nine months."
Mr McGonigal says the NZTA will closely monitor how effectively the partial reopening operates, and had not ruled out the possibility of allowing traffic to travel in both directions with stop/go operation, but only if it can be managed effectively and safely.
"We appreciate that this will still not be an ideal situation for everyone, as people will still need to use the Saddle Road when they're travelling towards Woodville and Hawke's Bay during the day, but it's a great step forward that will certainly provide relief for the region."
Mr McGonigal says this week's inspection showed that the bridges were damaged far beyond repair by the slip, and would need to be rebuilt.
"The bridges are a complete write-off, so we need to start from scratch building new bridges - and that's a big job."
"Building a new bridge across this distance in this challenging location would normally take up to twelve months, but we're not prepared to keep motorists waiting that long so we'll be working 24/7 where possible and aiming to get them rebuilt within four months."
Mr McGonigal said the NZTA was bowled over by the patience and support from the community, councils and industry during this lengthy closure.
"This has been probably the biggest disruption that this region has suffered in decades, but despite the enormous stress this has put the community under, people have taken it in their stride and remained positive.
"We simply can't thank the people of Manawatu enough for being so supportive and understanding, and we want to reiterate our unwavering commitment to getting the gorge fully reopened as soon as it is safe to do so. The job isn't finished yet, and we're going to see it through until the end, and beyond."
Mr McGonigal also thanked the teams from Higgins, MWH, Goodmans and the other contractors who had together contributed to the mighty effort of stabilising and clearing the gorge slip.
"The people who've put their boots on and rolled up their sleeves to get this slip cleared are legends, and they have done us all proud."
Mr McGonigal says the NZTA will continue its management of the alternative routes until the gorge fully reopens.