It's a challenging time for transport funding.

Treasury says Fuel Excise Duty or Road User Charges may need to go up in a year's time to manage pressures on the National Land Transport Fund and a loan granted to Waka Kotahi.

But, Transport Minister Michael Wood says he doesn't want to foreshadow Cabinet consideration of the upcoming transport budget.

Transporting New Zealand Policy Advisor Billy Clemens told Tim Dower there are challenges with the user pays model.

He says there's an increasing number of EVs on the roads that aren't paying Road User Charges and inflation of the cost to maintain roads.

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