11:31 AM: Just announced to address the south-downtown slowdown: Starting September 9th, SB Metro buses will be moved off 1st and onto 2nd, connecting to 4th. There will be a “longterm stop on 2nd Ave Ext. S. between Washington and Main to replace the SB stop at 1st/King.” More details to come.

12:21 PM: Just leaving the media briefing downtown. Also from the announcement: Starting September 12th – the projected start date of the Dearborn section of viaduct demolition – NB buses will be rerouted too, though that’s only expected to last a week and a half or so.

During that time, NB buses that use 99 will take 4th Ave. S. with stops at Prefontaine Pl. and James St.

The permanent pathway for buses is expected to open around the end of the year, the SDOT and Metro reps at the briefing said. Meantime, we asked what took so long to come up with this solution – couldn’t the problem have been predicted?

Metro’s Bill Bryant said it really took summertime traffic to kick in before they realized things weren’t going well. As for the month-plus it’s taken to come up with this, he indicated that they tried hard to see if signal timing and other nonrouting measures would help enough … but they didn’t.

The routing alone isn’t the only change planned; SDOT’s downtown mobility director Heather Marx said there remain many “moving pieces” in terms of signal timing and even channelization changes. Today’s announcement notes that “Buses using 2nd Avenue to connect to 4th Avenue S. will have a second left-turn lane from Columbia St. to 2nd Avenue.” And on 99, for example, the NB bus lane that was in place pre-tunnel will be brought back, possibly in time for the end of the Dearborn demolition.

2:57 PM: Commenter Kyle asked about data. We in turn asked Metro spokesperson Travis Shofner, who replied: