Tongariro Alpine Crossing hikers given 4 hours to do 19km, or risk clamping

The new parking restrictions come into force later this month. Photo / Getty Images

If you're planning on parking your car at the start of the Tongariro Alpine Crossing in order to hike the 19km trail, we suggest you work really hard on your fitness.

Hikers will have only four hours to do the 19km trail through the national park as parking restrictions come into force.

The Department of Conservation has introduced a 4-hour parking limit at the start of the walk.

The government agency's move is an attempt to reduce vehicle overcrowding at the popular hiking spot.

Hikers can alternatively park at the Mangatepopo car park and then pay for a shuttle to the start, at a cost of $30 per adult and $25 per child.

The Tongariro Alpine Crossing, one of New Zealand's most popular walks, is a 19.4km hike through Tongario National Park.

It takes the average person six to eight hours to complete.

The new parking restrictions will run from October 21 to April 30.