While that shadowy coalition of wealthy UCSF donors opposing the Warriors Arena plan is expected to unveil their own traffic impact report today, a city-commissioned environmental impact report on the arena also paints a bad picture of potential traffic problems extending to the Bay Bridge. Now, traffic coming from the east and south is just as much of an issue on Giants game days, and AT&T Park is more than twice the size of the proposed arena. But as Matier & Ross are reporting in the Chron, the opponents are going to try to argue that the traffic created by the new arena will be devastating, especially to UCSF, or something.

The city's report points to "11 key intersections" in SoMa where we'll see a “a significant impact” from the new arena 60 nights a year, when big concerts or basketball games are happening. That includes the impact of 1,000 extra cars over the Bay Bridge and 1,000 extra cars coming up 101 and 280, into Mission Bay.

None of this sounds particularly unexpected for a concert or sports venue, and the Warriors will continue to argue that the arena will generate $14 million a year specifically for traffic improvements. They're also saying they will provide extra traffic cops at intersections to help keep traffic moving.

The report notes that there's no feasible way to widen any of the existing on- and off-ramps, and that there will be "significant and unavoidable” backups on the freeway ramps at Fifth and Harrison and Fifth and Bryant Streets.

The report being created by the shadowy Mission Bay Alliance, which we'll add details of here once it arrives, is expected to detail significant impacts at 25 different intersections.

Can't everybody just learn to take public transportation?

Update: The press release has gone out and the Mission Bay Alliance is holding their press conference as we speak, at 11:30 a.m.

In their statement they assert several things, and they're focusing on the impact to the emergency room bay which is 1,050 feet from the proposed arena.

“Our engineers and experts have scrutinized the City’s draft EIR and determined with certainty that this is a fatally flawed project that will gridlock traffic, threaten patient access to lifesaving care and be a disaster for the Mission Bay neighborhood, the hospitals and City as a whole,” said Bruce Spaulding of the Mission Bay Alliance, a coalition of residents, UCSF employees, UCSF patients, and stakeholders who oppose the proposed Warriors’ arena.
The emergency room entrance to the newly opened UCSF Benioff Children’s Hospital is located about 1,050 feet from the proposed Warrior’s arena and entertainment center - “Yet incredibly, [the draft EIR] concludes that the subject project would not result in inadequate emergency access when capacity events are taking place,” writes Dan Smith, of Smith Engineering & Management, who was hired by Mission Bay Alliance to analyze the traffic and access study of the City’s draft EIR.
“The draft EIR offers no objective data to support its conclusion that emergency access would not be adversely impacted in event travel peaks,” Smith said.
Instead, the City’s draft EIR relies on subjective “rationalizations” for why emergency vehicles would not be slowed. When roadways are congested with cars and sidewalks are filled with rowdy crowds, it is an inconceivable conclusion that emergency vehicles will not experience delay, Smith concluded.

Previously: Warriors Arena Could Be In Serious Trouble, But Maybe Not