Rockfall on Whangamoa Hill has closed State Highway 6 between Nelson and Marlborough.
The road was closed at 2pm today after the slip, located between Rai Valley and Hira.
NZ Transport Agency Waka Kotahi (NZTA) said residents will be unable to access their properties until the road opens, except for those who live on Teal Valley Rd and Ross Rd.
“For those travelling between Nelson and Marlborough, continue to detour via SH6 and SH63,” it said in a statement.
Nelson police said online that detours are in place and motorists are advised to expect delays.
Marlborough to Nelson-bound traffic are to detour via SH6 to Renwick, on to SH63 Wairau Valley/St Arnaud, right at the intersection of SH6/SH63 Kawatiri Junction on to SH6 and north to Nelson – with the reverse for those travelling from Nelson to Marlborough.
Drivers, particularly those with ferry connections in Picton, should note the alternate route will add at least 30 minutes to travel times.
In an update at 3.50pm, NZTA said crews are working as quickly as possible to clear the debris, and there will be an update later this evening.
It comes after heavy rain over Labour Day weekend brought flooding, slips and landslides to the Marlborough region – photos show the sheer scale of damages.
Officers were photographed helping to paint protest signs.