Motorists travelling to Milford Sound after the Queen's Birthday weekend can expect possible delays for road resurfacing.
The single-lane Homer Tunnel will have closures in morning, afternoon and evening slots throughout the next fortnight.
Milford Road Alliance manager Kevin Thompson said crews had been regularly patching potholes and re-levelling the road. But the 1.2 kilometres of tunnel surface needed to be replaced, milled out by up to 10 centimetres and relaid, he said.
The work is scheduled from Tuesday until Friday between 10:30am and 12:30pm, and 1:30pm and 4pm daily.
From 8 to 12 June work is scheduled for 1:30pm to 4:30pm and 6pm to 10pm.
"To minimise disruptions for road users we are doing the work at a time when there is a lot less traffic using the Milford Road. Just how long it will take to complete this job depends on the number of winter weather disruptions work crews have to contend with," Thompson said.
"Tunnel closures will be needed, and wherever possible these will be scheduled at night or when traffic volumes are very low. Closures will be advertised before the work starts so road users have time to plan their journey.
"As long as we have some prior notice, we can accommodate anyone needing urgent access through the tunnel."
The New Zealand Transport Agency is investing about $1 million to re-asphalt the tunnel road and several nearby bends.
A mobile plant near Te Anau will produce the asphalt needed.