That’s the newest WSDOT video simulation taking you underground along the route of the “proposed bored tunnel.” Why do official documents – even the opening slate of the video – still call it “proposed”? That was one of the questions asked at Tuesday’s meeting of the South Portal Working Group, which meets periodically to receive and review new information about all the changes in the works for the transportation network feeding into this side of The Viaduct. Read on for the answer, as well as the toplines from the main focus of the meeting – how construction will be “staged” over the next five-plus years:

Turnout for this meeting was the lightest we’ve seen – about half a dozen of the group’s 20-plus members; they don’t vote or take any official action, though, so a quorum’s not required. Vlad Oustimovitch was the only one of West Seattle’s three reps who attended; also at the table, reps from Burien, South Park, the Mariners, the Amalgamated Transit Union, Mountain to Sound Greenway Trust, and the Frye Apartments, all far outnumbered by the reps of the various government agencies with a stake in the process, who were both on the other side of the table and in the gallery at Puget Sound Regional Council‘s Pioneer Square HQ.

The South Portal Working Group is one of three groups (including North Portal and Central Waterfront) that’s been meeting for almost a year now – and they are sometimes the first to hear about major developments in the tangle of construction projects that are just now starting to truly unfold.

Before getting to the construction staging, briefers had a few quick updates: SDOT’s Bob Powers mentioned the latest developments regarding the Alaskan Way Seawall, saying “It has a 1 in 10 chance of failing in the next 10 years – this thing needs to be replaced, and it needs to be replaced right now.” The Port of Seattle’s Mike Merritt reminded the group that construction is under way for the East Marginal Way Grade Separation overpass, and is on track to be done in September 2011.

The Spokane Street Viaduct Widening Project‘s two major components – the 4th Avenue offramp, to be done later this year, and the widening itself, which is just beginning – are both “on schedule and on budget,” SDOT’s Powers said, also mentioning that few realize the project also is improving the road and sidewalks beneath that stretch of elevated highway (between 99 and I-5).

Another project that’s been much-discussed in these meetings, though it doesn’t figure as prominently in West Seattleites’ frequently-used routes, is the Highway 519 tie-in by the stadiums; WSDOT is close to wrapping up two major parts of that project, with the Royal Brougham bridge (between Qwest and Safeco Fields) opening April 12th, and the I-5/I-90 offramp to South Atlantic Street overpass opening late April/early May.

And then – on to the construction staging for everything that’s happening between the West Seattle Bridge and the south end of the “proposed bored tunnel.” The biggest project is the replacement of the south end of the Alaskan Way Viaduct, and project head Ron Paananen says bids will be opened April 14th. In order to get that done with as few closures as possible, detours and bypasses will be built, and their implementation is part of the staging, with things just now starting to get complicated. “We kind of knew this day was coming,” said WSDOT’s Matt Preedy, in a wry understatement.

The briefing went through seven pages, one for each stage between this summer and winter 2015, followed by a page for 2016-2017. You can see it in its entirety here – each section looks something like this, albeit with slightly different color-coding and legend, depending on what’s happening (if the map part doesn’t make a lot of sense when you look at the full document, don’t worry, you can also get value just by reading along with the explanation text boxes on the right side of each page).

The briefing was meant so that working group members could each view the staging through their prism of interest, and ask questions if need be – earlier versions of this yielded some important concerns that led to changes, particularly in the way Alaskan Way will be changed as a result. And it’s one of the first stretches affected, with the construction of an “east frontage road” to the new South End Viaduct stretch, to be used as a temporary detour for Alaskan Way.

Bike/pedestrian path work will happen on the west side; that path is going to be 14 feet wide in most spots, project leaders say. The new path will be built in two phases – with the first one ending roughly parallel to north Qwest Field.

Bypasses and detours are the biggest things that will change your driving/riding – the latter may be more appealing, as buses will have some “queue-jumping” privileges in spots – life over the next few years, in this section. The southbound lanes of the new South End Viaduct will be built first, so southbound 99 traffic – headed our way! – is the first that will be detoured. A major part of the detour route will be through the property that’s been cleared west of Safeco Field, so as you see that get built, realize you’ll be driving on it before too long.

Late this year, southbound Alaskan Way will go down to one lane, as utility relocation continues.

Milestones in 2011 include 1st Avenue South returning to two lanes each way by June ’11, and the completion of the new bike/pedestrian path by April ’11. But that same period will take the south stretch of 99/Viaduct down to two lanes each way; there will be a northbound bus-only bypass between Spokane and Holgate. Then in the second half of 2011, construction of the “proposed bored tunnel” begins. (Yes, we’re still getting to the answer for the question of why it’s still described with that phrase.) And late 2011, West Seattle rep Vlad Oustimovitch was told in response to his question, is when the Spokane Street Viaduct 1st Avenue on/offramp is scheduled to be done. (WSDOT’s Preedy also noted that the 4th Avenue offramp, coming online later this year, should help 4th Avenue take some pressure off 1st, if all goes according to plan.)

One other thing to keep in mind for late 2011 – that detour west of Safeco Field will be 25 mph in spots, so even though you’ll have a through route, part of it will be slow going.

Then in May 2012, things start looking up; the new southbound Viaduct will be open to temporarily carry all the 99 traffic, two lanes each way (later it will revert to being three lanes southbound). But in order to tie everything together to make that happen, there will be a couple of significant closures – 10 days northbound, 4 days southbound. Once that’s done, major demolition will start on the Holgate-to-King section of the Southbound Viaduct, which, once it’s abandoned pre-demolition, will be a “weird” sight, Preedy noted, with the demolition planned in sections (about 100 yards of it has to go first for the tie-in).

And we’re going to stop the highlights here, because you can read along with the maps (again, they’re all here) if you really want to know what’s happening more than two years out. There weren’t many questions asked at the meeting – this seems to be the “take it all in and process it” phase.

By the way, in case you wondered about this – the South End Viaduct rebuild will not change anything about the 99 southbound offramp to the West Seattle Bridge. That’ll still be one lane.

If this all is making your head swim, don’t worry, the people planning it have had their challenges too. Quipped project boss Paananen, “This is only my fifth time (through the presentation), I think I need five more times before I really understand it.” But they’re trying to plan so far ahead that they can arrange to avoid conflicts – coordinating with sports teams and special events so that closures or other major disruptions don’t collide head-on with big SODO crowds, for example.

The South Portal Working Group will probably be reconvened in the second half of May, Paananen said, and among the topics will be the plan for “public outreach” to make sure this all starts sinking into the public consciousness.

Now, about the “proposed bored tunnel” – South Park rep Marty Oppenheimer wanted to know why that phrase is being used. The answer had nothing to do with politics; the environmental-impact reports for the project aren’t done yet, and won’t bring a final decision before mid-2011, so they can’t say it’s a definite go until that’s all complete.