The Seattle Mariners recently wrote a letter to the Seattle City Council, asking them for, among other things, a scheduling agreement between themselves and ArenaCo, the developers of the proposed Sonics and NHL arena in SoDo. In the letter, the Mariners - via the law firm of Hillis, Clark, Martin, & Peterson, P.S. - say that the new arena will house between 200 and 250 events a year, "far beyond use principally occurring during the baseball off-season." The letter then goes on to say that this will create a "Philadelphia-like volume, with many conflicting or overlapping events." It's funny that they mention Philadelphia, because in 2012, KING 5 reporter Chris Daniels traveled to the City of Brotherly Love to study the impacts of having three stadiums in close vicinity.
Daniels' 2012 report found that, through some mitigation, the three stadium area can work. Philadelphia has the Philadelphia Special Sports Complex District, and its executive director Shawn Jalosinski patrols the neighborhood during game days. They also have a scheduling agreement, similar to the one the Mariners are clamoring for.
The District, in cooperation with its neighbors, has set limits on how many people can attend events in one day (84,000), and can levy fines against teams who try to circumvent the rules. For instance, the Phillies and Eagles are not allowed to play on the same day (exceptions can be made during the playoffs). Jalosinski puts out a schedule of events at least a month in advance to warn commuters and residents about the possible impacts.
Traffic is a concern in Philadelphia's stadium district, but it's one that they were working on, as of the 2012 article. As neighbor Andrew Dankavich said to Daniels, "you live in an inner city, so it's inevitable. It's like saying you don't like water, and you live by the beach." As far as the neighboring Philadelphia Regional Port Authority, they have learned to work around the sports traffic and overall have few problems.
"We have to work around if there are multiple events at the same time," said [Sysco Philadelphia President Bill] Tubb. "But we don't run into much of it." He said the company's trucks typically leave between 1 a.m. and 6 a.m., and are off the road prior to 5 p.m. "Coming from other cities with other stadiums, stand alone stadiums, you experience traffic ten times worse."
Now, with the Mariners reinvested interest in a scheduling agreement, Daniels re-examined the Philadelphia situation, and how it could lend itself to a similar scenario in Seattle. If such an agreement were to mirror the one in Philadelphia, it would be beneficial for all parties involved. From April of 2015 to March of this year, there were a total of four dates that featured franchise events at multiple locations. Three of those events were in April of 2015. Also, there were 104 open dates on the calendar, where no sports, concert, or other events took place at any of the three stadiums. There were 38 "High Neighborhood Impact Alert" dates in that time frame, most of which included Philadelphia Eagles or Phillies games, with a few major concerts and one visit from the Pope.
The study did not include playoff games because, well, it's Philadelphia. Sorry Philly fans.
As Daniels says, it's not an "apples-to-apples comparison," but it's the closest look that we can get at what a Seattle Stadium District could be.