John Cridland said TfN now had decision making powers - but only regional leaders working together would have the “oomph” in negotiations with national leaders.
He was speaking at the launch of law firm CMS’ International Infrastructure Index report.
Mr Cridland said: “We now have the right in the North to make decisions, but the money still sits in London. It needs real partnership between leaders to get things done. Metro mayors are critical in areas to have the ‘oomph’ in negotiations with national leaders.”
In November, TfN became a sub-national transport body, which means the Secretary of State must take its demands into account when making transport infrastructure investment.
Manchester, Liverpool, Tees Valley and North of Tyne have elected mayors. Yorkshire will have its first, in South Yorkshire, in May.
The Government underlined its support for the model in the Budget. Six areas with a metro mayor will share half of the £1.7bn Transforming Cities Fund, with the rest of the country competing for the rest.
John Mothersole, chief executive of Sheffield City Council, said: “The Budget sent a very clear message the distribution of funds will be through mayors.
“In South Yorkshire, we are heading towards an elected mayor next year. I think the devolution model, with good leadership, can give stability and clarity.
“There’s a deal on offer at the moment and it should be taken.
“In Sheffield City Region we have done two devolution deals, a growth plan, we have an infrastructure plan, the only thing we haven’t done yet is elect a mayor. There’s a lot in place.”
Mr Mothersole also said metro mayors were collaborating to get things done.
“There are no hard boundaries, Andy Burnham does not confine himself to talking about Manchester.”
And for global investors, Transport for the North could promote projects large enough to tempt them.
Mr Mothersole added: “Transport for the North is a very bold successful example of something created by the North for the North. It gives clarity, it’s a landing point.
“We need to package up the opportunities across the North. We are talking about global funds. Any one city region is too small.”
Mr Cridland said transport played a critical part in boosting wealth and attracting investors.
“We have to fight really hard to be internationally competitive. Take five northern cities and connect them digitally and in transport terms and you’ve created a virtual city of 8m people.”
The CMS Infrastructure Index presents the top 40 countries in order of investment attractiveness and highlights the likely future trends across the sector.
The UK is ranked at number four.