The NZ Transport Agency advises motorists that the Manawatu Gorge will be closed during the daytime on Wednesday to allow for rock blasting.
NZTA Palmerston North state highways manager David McGonigal says crews will be blowing up large rocks that are sitting on the slope at a location 500m east of the site of the large slip site. The gorge will be closed from approximately 9am to 4pm, with motorists diverted to the alternative routes.
"We had a rock spill a couple of months ago which caused some damage to a half-bridge. There's some larger, more stubborn rocks on the slope just above, and we'll be blowing them up into smaller pieces that are easier to remove. This will get rid of a potential hazard and make journeys safer for motorists. It will also protect the road from further damage that could inconvenience motorists - we've had enough disruption in the gorge lately, and we're keen to stay one step ahead of Mother Nature as much as possible.
"To carry out this work safely, we'll need to close the gorge during the off-peak part of the day, and divert motorists over the alternative routes.
"We thank drivers for bearing with us during what we expect to be the final significant closure of this operation."
Rock blasting is commonly used at locations around the country, such as Nevis Bluff near Queenstown, to proactively remove rocks that could pose a potential hazard to motorists. It involves the controlled use of explosives to dislodge rocks, and is undertaken by teams of specially trained abseilers.
Mr McGonigal says the road will be stacked with hay bales to protect it from being damaged by rocks during the blasting. He says electronic information signs will be in place to keep motorists informed, and the work is being done during off-peak hours to minimise disruption to motorists.
While work is scheduled to take place between 9am and 4pm, these times are subject to change at short notice.