Without disclosing its price, Chris Hansen pledged Thursday to pay for the study, which he hopes will be concluded in between six to eight weeks by a private consultant.
"At the end of the day I am also a Seahawks, Sounders and Mariners fan. I think we all want a good solution for having games down in this area," said Hansen, who was flanked by King County Executive Dow Constantine and Seattle Mayor Mike McGinn.
Hansen has proposed a new arena that would cost between $450 and $500 million and would include $290 million in private investment. Hansen's group would also be responsible for the purchase of an NBA franchise and finding a partner interested in bringing an NHL franchise to Seattle.
He has already bought land in the city's SoDo neighborhood, which is home to the Mariners' Safeco Field and CenturyLink Field, where the Seattle Seahawks and Seattle Sounders play.
Hansen said he saw traffic as a "key benefit" in the stadium district when he undertook his own site evaluation.
But earlier this week, the Mariners sent a letter to the county and city opposing the idea of a new multipurpose arena, citing concerns about traffic and scheduling of events taking place in an area. The baseball team encouraged other sites in the region, including neighboring Bellevue, should be looked at before the spot in SoDo is developed.
The Port of Seattle also released a letter it sent to the arena advisory committee expressing its concerns over traffic in the area of the proposed venue and supporting the idea of looking at alternate sites.
On Wednesday, an arena review panel created by the city and the county gave their blessings for Hansen's arena plan but cautioned about the traffic issues.
On Thursday, McGinn said that the traffic study would look at the issues raised by the team and the port. He said that study will look at scenarios where multiple sporting events are happening, parking capacity, and mass transit options that will be available.
Hansen "is stepping up to get answers to those questions," Constantine said.
By 2016, Constantine said light rail connecting the stadium district to Seattle's northern neighborhoods would be completed, as well as the tunnel replacing the Alaskan Way Viaduct.
The public financing component of the proposal would be capped at $200 million and paid back through taxes and rent collected on the tenants of a gleaming new building.