Focus at the Tees Valley Combined Authority (TVCA) has remained on getting more government cash for work on a widened A19 Tees Crossing to begin.
But there have been new pleas for a road link downstream and now Tees Valley Mayor Ben Houchen has confirmed work will begin on what an underground project between Hartlepool and Redcar could look like.
Mr Houchen said a bridge downstream would limit the size of ships which could access the Tees.
If it ever came to fruition, the mayor said it would be a tunnel which would provide the link.
But he did not want to get hopes up on a tunnel arriving soon.
Mr Houchen added: “It would be like a Tyne Tunnel type of project to make it work.
"It is doable physically and operationally – you could get a tunnel under the River Tees.
“There is enough clearance on the other side to make it work and the wider transport connections are pretty good.
"It’s just getting the financials stacked up and selling the idea to the government to say ‘this is why we need the money’.”
The Conservative mayor added: “There are people who connect from Redcar into Hartlepool.
“But there aren’t enough to make the argument you should spend north of half a billion pounds to build an eastern crossing.
"We’ve got to build up the economies in Hartlepool and Redcar so as you get more economic activity. Then it improves the business case.”