The upgrades aim to boost tourism numbers and jobs at the Territory's third most visited natural attraction, which already sees 200,000 visitors annually.

First announced months ago, construction on new mountain bike hub shelters and mountain bike trails have begun, as part of a wider investment from the NT Government for new walking and bike trails across the Territory.

A tender for the design released last year in May revealed some sections will "co-exist" with already established walking trails and hampered by the steepness of the terain, he width of the trail was a concern for designers.

"Shared routes (mountain biking/walking) in Nitmiluk context should be sympathetic to and submissive to the surrounding environment. They should look like trails, not tracks/roads," the tender documents say.

"The off-road cycling experience design should specifically cater to non-technical riders i.e. those comfortable riding a bike on dirt trails, but not necessarily regarding themselves as 'proficient technical' riders and specifically not competitive mountain bike riders seeking 'adrenaline challenge' experience.

"The market would by and large be a 'hire market', boosting the economic argument for trails investment, via increased economic stimulus and employment through establishment of service provider businesses (hire, maintenance and guiding)."

Member for Arnhem, Selena Uibo said the upgrades will provide more reasons for people to visit, and more reasons for them to stay longer.

It is part of the government's wider NT Mountain Bike Master Plan to establish the Territory as the adventure riding capital of Australia.

"Mountain biking is an increasingly popular recreational activity and visitor attraction, the investment in infrastructure in Nitmiluk National Park will improve the visitor experience, and support local jobs in construction, and in tourism," she said.

Helicopters will be needed to deliver some of the material to construct Nitmiluk's new mountain bike trails, as mountain bike signage, frames for the shelters and posts need to be delivered to hard to navigate to locations.

Acting Minister for Tourism, Sport and Culture, Eva Lawler says she expects the investment to cement the Territory as a biking mecca within Australia.

"Tourism is a key economic driver in the Territory, and our national parks are one of the main reasons people visit. Investing in our parks is not only an investment in our tourism sector but also in the liveability of the Territory - Territorians love our parks just as much as visitors from interstate and overseas do," she said.

"Mountain biking and adventure tourism are growing in popularity, and improvements to trails in the Territory will help put us on the map for people looking for such experiences."

A new causeway over the Katherine River is also in the works.

The NT Government has been contacted for more information on the causeway.

All we have so far is this from a government spokeswoman: "A cement causeway over the river that provides extended access to the northern part of the park for Nitmiluk Tours guests, Parks staff (so greater access for land management purposes) and Traditional Owners."

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