Transportation study finds 'no fatal flaws' in Sodo arena plan

An independent study on the proposed new sports arena's effect on congestion in Seattle's Sodo neighborhood has found that the existing infrastructure could support the thousands of additional cars and people who would attend NBA and NHL games.

Even on weeknights with two events -- one at the arena, one at Safeco Field or CenturyLink Field -- existing or planned parking lots and transit options could handle the extra traffic, says the study, which was released Wednesday after about six weeks of work. The impact on operations at the Port of Seattle, surrounding industries and train yards would be minimal, the study found.

"We don't see a fatal flaw here," said Bob Chandler of the Seattle Department of Transportation.

The study, conducted by Auburn-based firm Parametrix and paid for by arena investor Chris Hansen, took a look at the estimated turnout for a 20,000-seat multipurpose sports venue and found that 6,000 cars would descend on the area for an average weeknight game. There would be about 52 additional weeknight events in Sodo per year, including about nine weekdays when Mariners or Sounders games overlap.

With most arena events starting at 7 or 7:30 p.m., and most port operations closing at 4:30 p.m., there would not be much conflict between freight traffic and sports traffic, the study found. Representatives from Parametrix and SDOT also pointed out that most freight traffic is west of First Avenue South, separate from most sports traffic on First Avenue South and eastward.

"We really don't see a lot of conflict with those (freight) movements," Parametrix's John Perlic said at a news conference Wednesday. "Even if the container traffic at these (closest) two (shipping) terminals grow, and the hours of operation expands into the evening or weekend time periods, those movements are pretty much separated from (arena) events that occur."

The Seattle Port Commission has continued to warn that fast-tracking arena development could threaten the city's working waterfront and the thousands of jobs it supports. Just Tuesday, the commissoners released another letter that raised concerns over extra traffic and scolded local leaders for being cheerleaders of the proposed arena.

SDOT's Chandler on Wednesday said most of the port's fears should be assuaged by current improvements to the Spokane Street Viaduct and the forthcoming Atlantic Street overpass. The Atlantic Street overpass, which will provide a direct link between the port and the train yard just east of state Route 99, is part of the Alaskan Way Viaduct tunnel replacement project and should be completed by the end of 2015 -- before the arena is expected to be finished.

"There have been longstanding, historic issues in this area," Perlic said. "I believe a lot of them have been addressed with the planned projects that have come online and will come online in the next couple of years."

Nevertheless, the port is looking beyond the short-term. With the widening of the Panama Canal, Seattle's port is facing major competition from other West Coast harbors and even ports as far away as South Carolina.

"The city and the port will contine to work together to make port operations more efficient," Chandler said. "We've touched on some of this stuff we've been doing -- there's more that we will be talking with the port about, both short-term improvements and longer-term improvements.

"Because we need to keep the port in a place that those operations between the terminals and the rail yards are functional. We're just going to continue to work on that. And I don't think that will ever completely be taken care of, because technology changes over time."

The proposed arena site, located just south of the Safeco Field parking garage, is already in the city's designated stadium district. Hansen, the San Francisco hedge fund manager who wants to build the new arena, has acquired or reached agreements to purchase all of the land he needs to build a multipurpose sports venue for NBA, NHL, entertainment and other events.

Hansen's proposal went public in February when Seattle Mayor Mike McGinn and King County Executive Dow Constantine announced that a private investor wanted to bring the SuperSonics back home. Under the current proposal, which is now being deliberated by the city and county councils, an arena would be built using, in part, $200 million in public loans. Seattle-raised Hansen and his group of investors would contribute up to $800 million in private capital for arena construction and acquiring the teams.

The transportation study assumes that the project will include the addition of 3,500 new parking spaces, including 1,500 at the new arena and 2,000 more at other locations in Sodo. 

Parking would be ample on weeknights when there are events only at the arena, since the venue would seat fewer people than the average Mariners game crowd. But on multiple-event weeknights, the study found, parking could fill up a three-quarter mile radius from the arena -- a 15-minute walk through the streets of Sodo, mostly during winter.

The study projects that 82 percent of arena patrons would drive, 8 percent would use a bus or train, 4 percent would take a ferry, another 4 percent would walk and 3 percent would bike or use another mode of transportation. As the Link light rail system is built out, those percentages would shift more toward public transit, Perlic said.

Last football season, just 57 percent of Seahawks fans used cars while 17 percent used rail, 12 percent took a bus and 14 percent walked, biked or rode a ferry. But because Seahawks games are generally on Sundays, the arena traffic is expected to be more car-heavy.

Using Link's Stadium Station would give people a 10-minute walk southwest to the new arena -- at least using existing pedestrian routes. 

For its findings, the study assumed a new arena that seats 20,000 people, though the proposed venue is expected to seat about 18,000 for sports events and 19,000 for concerts. The study also assumed the average weeknight Mariners game draws 37,000 people, even though the average attendance during the 2011 season was about 23,000. The average crowd at CenturyLink is 38,500 for Sounders games and 67,0000 for Seahawks games.

Parametrix determined that, with a new arena, there would be four weeknights per year during which there are both a Mariners game and an arena event. There would likely be two weeknights with both a Sounders game and an arena event.

Weekends could be a different story, with a potential 33 days with overlapping events, including not just sports games but also other events. And there could be extra multi-event weeknights if one or more Seattle sports teams make the playoffs.

"We thoroughly looked at the overlapping-event scenario and (determined) that the existing-plus-planned transit capacity, and parking increases, can accommodate these events," Perlic said.

The entire transportation study can be downloaded as a PDF from Seattle.gov.

Seattlepi.com's Joel Connelly contributed to this report. Nick Eaton can be reached at 206-448-8125 or nickeaton@seattlepi.com. Follow him on Twitter at twitter.com/njeaton. Visit seattlepi.com's home page for more Seattle news.