AT's Chief Executive is sounding the alarm over the agency's uncertain revenue model.

Speaking to the agency's board meeting on Tuesday, CEO Dean Kimpton called for more certainty in the agency's current funding model.

He explained that AT needed to maintain their future investments, the cost to deliver those investments and be clear about what's needed over the next decade.

"We've got to put this issue on the table. If we do not reconcile, an asset base will grow from $26 billion to $40 billion over the next 10 years, public transport will double in numbers from 100 million to 200 million passengers."

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