Nineteen months after Seattle promised a written policy manual for dealing with major traffic incidents, the city has not yet completed that manual.

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In 2015, after a fish truck crashed on Highway 99 and clogged Seattle traffic for nearly nine hours, the city hired two outside consultants to tell them how to better manage similar traffic incidents.

A top recommendation, touted by Mayor Ed Murray in July 2015: establish a citywide traffic-incident-management program, by creating a manual detailing policies and procedures for departments to follow.

“The steps we are taking will help improve our response time and get traffic flowing after incidents as quickly as possible,” Murray said at the time. The city had already begun implementing the recommendations, he said then.

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So on Monday, did the city follow this new policy manual after a propane tanker truck crashed on Interstate 5, shutting down the freeway and diverting thousands of cars onto city streets?

It did not. Nineteen months after it was recommended, the manual has not yet been written.

The Seattle Department of Transportation has submitted some recommendations to the City Council, an SDOT spokeswoman said Tuesday, but she was not sure when they were submitted or the result.

The mayor’s office did not respond to a request for comment Tuesday evening.

Monday’s crash, just south of the Interstate 90 junction, was more complex to clear than the 2015 wreck because it involved a truck carrying highly flammable propane as opposed to frozen cod. Crews spent much of the day transferring the liquid propane to another tanker.

Seattle did change its priorities after the fish-truck crash — emphasizing the need to reopen roadways rather than protect cargo involved in the crashes.

And unlike Highway 99, the city does not have responsibility for I-5; that lies with the Washington State Department of Transportation (WSDOT) and the State Patrol.

Seattle has also dedicated nearly $2 million in its 2017-18 budget to improving traffic-incident response, including increased staffing and training for emergency crews.

But as the hours ticked by Monday, the midmorning crash coupled with a burst of afternoon snow to produce nightmarish evening congestion that spread like a virus throughout the city’s core.

Buses stuck

At peak, hundreds of King County Metro buses were running at least 90 minutes late, Metro spokesman Scott Gutierrez said.

At one point Monday evening there were 10 D-Line buses stuck in a five-block span near KeyArena. Around 6:15 p.m. there were 13 buses stuck in the Westlake Avenue North transit lane, unable to move from South Lake Union through downtown.

Metro has about 50 routes that travel on I-5, I-90 or the 520 bridge, Gutierrez said, all of which had to be at least partially rerouted, although most did not miss any major stops.

He said there wasn’t really much of an option to reroute buses, because congestion was everywhere.

“Pretty much every street downtown was filled with traffic,” Gutierrez said. “I don’t know that there were a lot of options.”

Despite the lack of a citywide manual for dealing with traffic incidents, at least a half-dozen city, county and state agencies coordinated to deal with Monday’s events.

The 911 call on the toppled propane truck was forwarded to the State Patrol at 10:08 a.m. Monday. Freeway closures began 40 minutes later, followed quickly by signs on major streets notifying drivers about the blockage. The truck driver and two other motorists were taken to the hospital with non-life-threatening injuries.

From its traffic-operations center, on the 38th floor of the Seattle Municipal Tower, city traffic engineers altered traffic-signal timing throughout the central business district, Aurora Avenue North and other locations, in an attempt to relieve congestion.

Both the state and city have written plans to maintain mobility in earthquakes, including an Alaskan Way Viaduct closure, but WSDOT does not have a formal plan to deal with an I-5 blockage, like the propane-truck crash.

That’s because I-5 around Seattle constantly suffers major blocking crashes, giving the agency plenty of practice, the state says. Outlying areas do have formal freeway-disruption plans — for instance, during the I-5 Skagit River Bridge collapse in 2013, when traffic maneuvered between Burlington and Mount Vernon using parallel Riverside Drive.

“Here in the metro area, we don’t need to have that written on a map because they’re exercised daily, and we have a higher level of communication and coordination with the local agencies,” said Dave McCormick, WSDOT assistant regional administrator.

A 2002 state goal calls for nonhazardous loads blocking a road to be moved within 90 minutes. Fatal truck crashes average six hours to clear. About half of congestion results from collisions, and WSDOT operates one of the nation’s pioneering incident-response teams to clear ordinary wrecks fast.

Tactical choices

McCormick says the state made some tactical choices Monday to help drivers.

High-occupancy exits in downtown Seattle were opened to all traffic, to drain vehicles from the clogged southbound I-5 express lanes. Still, there were about 60 vehicles, mostly big trucks, that were stuck at the south end of the express lanes. Troopers escorted them past the crash, McCormick said.

Despite that challenge, the express lanes were emptied and switched to northbound by 1 p.m., to help drivers leave downtown.

Still, hundreds of I-5 users waited for hours, already too far forward to use an exit. Some went in reverse or backtracked to flee the freeway. But no official detours were attempted, McCormick said.

WSDOT flashed messages on freeway signs as far as Tacoma, along with numerous social-media posts and alerts, McCormick said. Another tactic, well-known from other incidents, was to send cars off I-5 and along Airport Way South to reach Sodo.

Southbound drivers seemed to get the message to leave I-5 miles before the scene. At 6 p.m., right before the tanker truck was cleared, the traffic-flow map showed no congestion north of the University District.

Difficult to clear

The load of propane made Monday’s crash much more difficult than the frozen-fish crash.

Propane is highly explosive, vaporizes when released, and the clouds can become concentrated enough to explode.

Fire officials understood this and cleared out homeless camps under the freeway, so campfires wouldn’t ignite any leaking gas.

Could the propane have been released or burned off, to save time?

Probably not, based on experience in a Dec. 21 tanker crash near Buffalo, New York, which caused a slow propane leak 500 feet from a highway hotel.

Firefighters decided to burn the propane, instead of transferring the liquid, because a crushed valve made a hose connection unworkable, Lackawanna, New York, Fire Chief Ralph Galanti said Tuesday.

That took five hours, even though the hazmat team used a specialized device shaped like a Bunsen burner and burned off only 2,000 gallons of the 3,500 gallons before setting the crashed truck upright and moving it.

Buffalo’s Highway 5 was closed nine hours altogether, for a truck with far less than the 9,500-gallon capacity in the Sodo crash.

“Route 5 is a major artery in and out of Buffalo. We wanted to make sure we got done by rush hour,” Galanti said.

Nationally, there are about four crashes per day involving tanker trucks carrying flammable loads.