A Seattle and King County study on the traffic effects of a proposed NBA/NHL arena in the city's Sodo district found Wednesday that two sports events on the same day would be "manageable with the existing and funded transit investments in the area."

In addition, the study, which was funded by investor Chris Hansen, who has proposed building a $500 million arena, said that on days with arena events only, there would be about 6,000 vehicles added to the area, "which is well within the existing parking, traffic and transit capacity in the area."

The study said thgat, "Enhanced use of technologies such as an e-park system, changeable freeway and arterial street sign directions, and game day mobile apps would benefit all of the venues, including Safeco Field and CenturyLink Field, enhance the fan experience, and reduce congestion in the area."

The Port of Seattle Commission sent a letter to the Seattle city and King County councils on Tuesday outlining port concerns about possible impacts to freight and transit movement  through the Sodo district.

"Though this initial study was understandably limited in scope given the brief study period, it offers a starting point for the city and county councils as they consider the agreement before them," the Port of Seattle said, adding that it looks forward to upcoming council meetings on the Port's concerns. 

John Persak, a member of the executive board of the local chapter of the Longshoremen union, said, "The traffic study is inadequate and woefully incomplete. It does little to characterize the true traffic issues in Sodo. We knew that a study of such limited scope would do little more than provide talking points for arena promoters and sports radio.”

The concern is that a new arena adjacent to Safeco and CenturyLink Fields and the Port of Seattle would make parking and overall traffic a nightmare.

The Sodo Business Association and the Seattle Mariners' chief executive officer have both expressed concerns about Hansen’s proposed sports and entertainment arena.

But Hansen said traffic in the area was actually a selling point to him. 

“When we undertook a site evaluation, traffic was one of the key benefits of this area, and when we looked at other potential sites we thought this was one of the best, but that doesn’t mean there’s not issues down here,” Hansen said at a news conference.

Many believe the answer is something that was once planned to alleviate traffic in Sodo – an overpass at South Lander Street that would allow trucks to travel from the Port of Seattle terminals to Interstate 5. But the price tag would be high.

"Significantly over $100 million,” said Peter Hahn, the director of the Seattle Department of Transportation. “And for anything of that nature, it's a challenge for the city to do.”