Fiordland's Homer Tunnel has finally had its $29 million upgrade completed, just as tourist numbers are forecast to return to pre-covid levels, with the most visual improvement being a new avalanche shelter at its eastern entrance.

The finished eastern entrance to the Homer Tunnel with its unique artwork. Photo: NZTA

The Homer Tunnel is part of State Highway 94 - the Milford Road - which is the only road access to Piopiotahi Milford Sound - one of Aotearoa New Zealand's major tourist attractions.

The new shelter, part of a $29 million government project to improve the safety and resilience of the Milford Sound portal, was started in November 2022 and replaces an earlier 70-year-old shelter that had been largely demolished due to repeated rock falls and avalanches.

Other work completed as part of the project includes radar and incident detection cameras, speakers and lighting, an upgraded power supply, cabling protection, in-tunnel barrier and in-road sensors.

During demolition of the existing 70-year-old avalanche shelter, the Homer Tunnel's original 1953 stonework was revealed. Photo: NZTA

An additional traffic lane at the eastern entrance and improvements to the microwave/repeater site has also been completed, along with a tunnel plant equipment room - buried into the ground for both protection and aesthetics.

NZTA Waka Kotahi Project Manager Chris Collins said the remoteness of the site and the weather had been the project's major issue.

"With an annual rainfall of about seven meters a year, it is a challenging site."

The design was also unique, not only because it ran out into a valley - instead of hard against a hill like most overseas shelters, but also because the design had to work around an operating road, Collins said.

He said the use of precast units - for fast installation - had helped minimise the disruption of traffic going through to Milford and the tourist operations.

"It was a complicated exercise in the design to get that all right."

"[It] was all done on a computer. And that resolved all the issues so that when it got to site, it was just like building a Lego set."

"It all went back together nicely, so that was a major achievement," he said.

Collins said they had chosen night-time to close the road for operations in order to not inconvenience tourism operators or tourists and had used the Milford Road Alliance networks to keep locals informed.

"That worked extremely well and [we] got compliments back about that," Collins said.

Collins said he definitely had a sense of pride for everyone who worked on the project.

"We're all extremely proud of it and proud how easy that design worked and went together.

"It's a one off. It's a very unique structure - around the world even - because of where and how it sits within avalanche zones."

"Avalanches around the world are measured on a scale that goes from one to five. And in the past at the Homer Tunnel they measure them as five pluses. So it's a structure to stay within a huge potential avalanche zone."

Precast structures are put into place as part of the Homer Tunnel upgrade. Photo: NZTA

Milford Sound Tourism CEO Haylee Preston said the tunnel was now looking world class and anything that improved safety for those visiting or living in Milford was positive.

Preston said thanks should also go to those who call Milford Sound home because they were the ones that had faced the majority of the disruption during the upgrade.

"They've just had to really plan, because with the closures at six o'clock at night, they had to make sure that they were back in early for [their] shifts."

"Some nights they weren't able to access their house or get home," she said.

Preston said she expected up to 750,000 people would visit Milford Sound this year - up to 90% of pre-covid rates, while Winter (July - September) bookings already suggesting numbers would hit pre-covid levels.