By year’s end, there’s supposed to be a plan for what will happen when the Central Waterfront mile of the Alaskan Way Viaduct comes down in 2012. Since that plan will affect West Seattle mobility in a big way, community leaders have been working to make sure they and their groups are plugged in to the latest information — and that’s the reason most of last night’s joint meeting of the Southwest and Delridge District Councils focused on what’s up with The Viaduct. They got a heavy-hitting panel of top transportation execs to present the briefing — WSDOT’s David Dye, SDOT’s Bob Powers, and King County Department of Transportation director Harold Taniguchi. In addition, meeting participants included the two West Seattleites who serve on the Stakeholder Advisory Group that’s been helping vet Central Waterfront possibilities — Delridge District Council chair Pete Spalding and Fauntleroy Community Association‘s Vlad Oustimovitch. Here’s what happened in the meeting:

At the heart of the presentation was a review of the eight options currently under consideration for the Central Waterfront section of The Viaduct – though attendees were also reminded that the Central Waterfront Project is only one of several involving The Viaduct (the others are the column-shoring-up that was completed recently, utility-line relocation that will start soon, Battery Street Tunnel safety upgrades, stabilization on the north end near the tunnel, the South End Project that gets under way next year, and transit enhancements such as those discussed in the county briefing we covered earlier this week).

We first told you about the eight Central Waterfront options the day they were unveiled (WSB coverage here); you can see them in great detail in documents on the Alaskan Way Viaduct website (look for A through H).

But a key takeaway from last night’s briefing and discussion was a reminder that the final result is not likely to be any one of these options in particular – elements are more likely to be mixed and matched. Which elements, depends on key information that will be publicly available soon – evaluation of the options and their components, from potential cost to potential impact on commuting times. Taniguchi used a cooking analogy: “We have basic recipes – we’re trying to have command of certain elements of recipes, what if we mixed and matched to see if a meal actually worked?” It was also noted that the process has moved beyond simply evaluating this transportation corridor, to looking at the “regional transportation network,” from Lake Washington to Elliott Bay.

That was a major point of concern for those who were in attendance last night: Say, for example, the end result is a surface option like A, B, or C, centered on a waterfront boulevard with traffic signals, and therefore vehicles going much more slowly than they do now (when The Viaduct isn’t backed up, anyway) – how will transportation planners be sure that won’t cause a chain-reaction catastrophe on the West Seattle Bridge and streets that feed into it, like Delridge?

SDOT’s Powers said that once the evaluation information is in for the potential options, they will be able to crunch those numbers too, from data that already exists regarding road usage. What about the future development that will add thousands of residents to West Seattle in just the next few years? asked Junction Neighborhood Organization president Erica Karlovits. Powers said SDOT is working with the Department of Planning and Development (DPD) to be sure that’s taken into consideration too.

Back to the eight options: In case you still haven’t heard a lot about them, they fall into two groups: Three “surface” options, A through C, and elevated or tunnel options, D through H. Most of them don’t fully replace the “capacity” that will be lost with the removal of the current Central Waterfront section of The Viaduct, so most include plans for additional transit, buses and/or streetcars. (Still no West Seattle streetcar under consideration right now, though, which was a point of contention for some questioners; the government reps say The Bridge is the problem — OK, one attendee suggested, so how about a streetcar in West Seattle, to get people to the Water Taxi? One interesting side note that emerged, in response to a question from Southwest Council co-chair Steve Sindiong: Viaduct traffic breaks down to 40 percent headed to downtown, 60 percent just passing THROUGH downtown.)

Many people may be watching the basics of what will replace the Central Waterfront section — elevated? tunnel? surface? — but some of the auxiliary elements are providing the most interest. Among those discussed at last night’s briefing: “Active traffic management” — which was described in terms such as, slowing down I-5 traffic toward the city, south of the West Seattle Bridge bottleneck exit to northbound 5, so that traffic would be distributed more evenly in the gaps along the south Seattle stretch and beyond; that could mean variable speed limit signs showing different numbers at different times (no more “one speed limit fits all, at all times”). Electronic signboards showing where to park downtown (since downtown parking may undergo major changes – angle parking changed to parallel on certain streets so another traffic lane can be added, for example) could be part of the mix, and real-time bus information – such as that planned at Rapid Ride stops – too.

Two points were stressed: There’s still plenty of time to get in your two cents on what should be done — before a final decision is reached, the list is supposed to be whittled down to three options — in the following ways: For one, you can attend the Stakeholders Advisory Committee meetings (a new schedule has just been posted on the Viaduct website – they have been meeting monthly but will be adding some extra sessions as the process draws closer to a close) – one note, as the government reps pointed out during the briefing, this committee will not be making a decision; its job is to offer informed opinion on what’s being discussed. For two, you can attend more public briefings: In addition to the West Seattle Chamber of Commerce‘s transportation forum next Tuesday night at West Seattle High School (6 pm open house, 7 pm moderated Q/A), the next official Viaduct open house in West Seattle is 5:30-7 pm September 16th at Fauntleroy Church (here’s our post from last week). And you can send e-mail or postal mail – the Viaduct website has full information on how to do that.

WHAT ELSE HAPPENS NEXT: Groundbreaking for the utility-line relocation work is scheduled for September 12th. Dye says this project “won’t have a whole lot of traffic impacts,” though, because most of the work is happening on what’s described as “private property west of 1st Ave. So.” The South End Project — which Dye describes as “really the big one” — remains in design; it’s a $450 million plan to replace the entirety of The Viaduct, from Holgate to King, and you can read about it here. He says the goal is to keep “two lanes moving in each direction on 99” during that work, but there will be occasional exceptions; construction is scheduled to start in fall of next year.

WSB coverage of the Alaskan Way Viaduct is archived here.