(ADDED EARLY TUESDAY: SDOT manager’s memo about how this unfolded)

(Photo added 2:23 pm, by Christopher Boffoli for WSB)
12:49 PM: Thanks to the tipsters who have messaged us about at least one crash on the eastbound bridge, possibly more. Checking.

(Police blocking 35th/Fauntleroy bridge entrance)
1:04 PM: Bridge being blocked at 35th – multiple incidents, and emergency-radio traffic indicates de-icer suspected.

1:18 PM: Police at 35th/Fauntleroy tell us entire bridge is closing. Fauntleroy is closed eastbound at Avalon, and that’s causing a backup all its own – here’s the closest traffic cam (refresh for latest “live” image):

1:28 PM: Scanner confirms SDOT crews are responding to put down sand/”material” to “combat the slickness” – also to fix the jersey barrier damaged by at least one of the crashes. The slickness was noticeable on the road at 35th/Fauntleroy – we were wondering where what looked like water had come from – when we passed through, just before getting word of how serious this situation was. Radio indicates that ALL access points to the bridge are being closed – including from I-5 and from Beacon Hill (Columbian Way).

1:37 PM: As you’d expect, the low bridge is reported to be backing up too. One way to get back to West Seattle if you need to: Take 1st or 4th southbound to the 1st Avenue South Bridge, get off at the South Park entrance but head north and then west up Highland Park Way back into WS. (Added: Some people are apparently still using the westbound bridge because, according to radio traffic, the I-5 entrances haven’t or hadn’t been blocked off.)

(City crew working on bridge by Fauntleroy-approach curb; WSB reader photo)
1:48 PM: Now there’s word of a spinout on southbound 99/Alaskan Way Viaduct.

(WSB photo: Backup on 35th approaching the bridge)
2:30 PM: Roads that approach the bridge are backed up. SDOT crews are on the bridge working to combat the slickness. Buses that usually take the Viaduct/bridge are rerouted onto the low bridge until this clears. Until it’s over, leaving or heading toward West Seattle is best advised from the south side, through Highland Park. The South Park Bridge was drawn open for a while but commenters say it’s closing now.

2:40 PM UPDATE: From Rick Sheridan at SDOT:

With colder temperatures approaching, SDOT applied liquid de-icer to the high-rise bridge as a pretreatment prior to the evening commute and football game.

Due to current warm temperatures, the de-icer can create a brief period of slippery conditions, especially if vehicles are traveling above the posted speed limit.

Out of caution, SDOT is applying sand on both directions of the structure to address any traction issues. We expect the bridge will reopen by 3:00 p.m.

2:46 PM UPDATE: To our followup question regarding whether there was anything different in the formula or the amount, Sheridan replied, “Not that we are currently aware of.”

2:52 PM UPDATE: Eastbound bridge is reopening now, per scanner. And westbound opening “in a few minutes.” Here’s the “live” bridge camera:

(East-facing camera on the West Seattle Bridge; see other cams on the WSB Traffic page)
3:06 PM UPDATE: The official call just went out – westbound is reopening too.

3:53 PM UPDATE: The 99 southbound ramp to the westbound high bridge apparently has lagged in reopening – a commenter says his crash scene isn’t clear there yet. Meantime, this isn’t the only time de-icer has been blamed as a factor in crashes – via Twitter, @cooljames points out this Whidbey Island report from 2008.

4:15 PM UPDATE: Per commenters, the ramp from 99 to the bridge is now open TOO – but remember, traffic remains tougher than usual with the Seahawks game an hour and a half away.

4:38 PM UPDATE: We asked City Councilmember Tom Rasmussen, the West Seattle resident who chairs the council’s Transportation Committee, if he would be looking into this. Short answer: Yes. Longer answer:

Earlier today, prior to the de-icing related accidents, I spoke to the SDOT Director about preparation for freezing weather, which is predicted tonight and through the week. Record cold weather may be on its way next week.

This should be considered a significant incident by SDOT and I have requested the Director to provide me with a report as soon as they are able to piece together what happened and why. I will let West Seattle know what I learn as soon as I receive the report.

The Director will also brief the Transportation Committee on Tuesday, December 10. The meeting begins at 9:30 AM and will be televised on the Seattle Channel.

ADDED EARLY TUESDAY: Councilmember Rasmussen forwarded e-mail he received from an SDOT manager explaining how it unfolded. Here, verbatim, is what SDOT’s Steve Pratt wrote:

Based upon all the available forecasts on hand at 8 AM today, 12-2-13, we made a
decision this morning to apply our anti-icing pretreatment to the WS High Rise, the AWV, Aurora Bridge, and a couple of other sites around Century Link Field, (bridges over ARGO, etc). We started this work around noon as the “cold snap” that was in the forecast as late as 9:23 AM from WeatherNet was calling for hail/ice in the time frame of 1-3PM. Our effort was to get ahead of any ice and or sudden temp drops such as occurred on 11-22-2010. We were also concerned about the traffic volumes headed for the MNF game which were predicted to start building around 3PM.

We applied MgCl on the WS High Rise between 12-1PM. I drove the bridge westbound at 12:10PM and then returned eastbound at 12:50PM, after stopping for a quick lunch at the Chelan Café. The application was completed by the time of my return trip. I observed that the road surface appeared “wet” and that the MgCl had not “set up” yet. I accelerated the vehicle I was driving a couple of times in the eastbound lane and did not break traction. When I arrived at the Chas. St. office at 1:02PM I was informed that there had been “some accidents” in the eastbound lane. It turns out that these were in the curve above the steel company, NUCOR, about 100 ft. to 250 ft. north of the pedestrian bridge north of 35th/Fauntleroy. We immediately contacted our driver and had him stop applying any more MgCl. He had treated the Aurora Bridge (with no incident) and had treated the southbound curb lane on the AWV between the Battery St. Tunnel in the short section that is “open air” before it tucks under the northbound upper deck structure, with no incident.

Several things occurred during this incident. The deck on the W. Seattle bridge was warmer than our usual application time, (during the night for AM commutes), and the material did not “set up” as quickly as we are used to, (ten to fifteen minutes). The accidents were all in the same section, all in a downhill curve where cars naturally pick up speed. There were NO accidents in the West Bound lanes anywhere on the W. Seattle bridge or its appurtenant streets.

SPD made a decision based upon the safety of the motoring public to close the Eastbound Lanes, and then they subsequently closed the Westbound Lanes. They requested that we apply sand to the surfaces on both sets of lanes. We mobilized our folks out of the W. Seattle shop to accomplish that and the east bound lanes opened back up at 2:52PM and the west bound lanes at 3:08PM. We coordinated these activities with SPD.

The intent of this effort, the application of the MgCl, was to get ahead of the predicted cold snap to freezing temperatures by 3-5PM. The forecast was wrong.

MgCl is magnesium chloride.

(East-facing camera on the West Seattle Bridge; see other cams on the WSB Traffic page)

Will we have weather wildness? Won’t know until we see it (or don’t see it), but here are some things we do know, as the week begins:

MONDAY NIGHT FOOTBALL AT THE CLINK TONIGHT: Be mindful of the traffic ramifications. Game time for the Seahawks and Saints: 5:40 pm.

NO MORE DELRIDGE DETOUR: Thanks to a tip, we reported Friday that Delridge Way SW is now fully reopened, after what appears to have been an early end to the bulk of the final and southernmost phase of the almost-year-long paving project.

26TH SW TEMPORARILY NARROWED: South of SW Genesee, 26th SW is temporarily home to about a dozen big white-covered modules that will be turned into townhouses nearby this week, so drive carefully if you use that stretch. Here’s our report from Saturday; at last report, the work was penciled in for Tuesday/Wednesday.

METRO MEETING TUESDAY NIGHT: No transportation-funding solution yet, so Metro continues to proceed as if it will have to make those dramatic service cuts outlined last month. Find out and speak out about them at Youngstown Cultural Arts Center tomorrow (Tuesday, December 3rd) night, 6-8 pm.

HIGHWAY 99 CLOSURE NEXT WEEKEND, NORTH OF BATTERY ST. TUNNEL: Early heads-up – midnight Friday night until 5 am Monday morning, Highway 99 will be closed from the Battery Street Tunnel northward to Valley Street “while crews switch the roadway from the west side of the street to the east side of the street.”

BICYCLE MASTER PLAN UPDATED: In case you haven’t seen it yet – the final proposed updated version is out, and will be aired at a round of meetings starting this week. Your comments are invited too. SDOT explains, here.

Check back for today’s traffic updates, as/when needed!

**MONDAY AFTERNOON NOTE: For full coverage of this afternoon’s de-icer debacle, which closed the bridge for two hours, go here.**