I-5 bridge over Skagit River collapses

[Kacie Jane]

Ummm...all this politicking is essentially a moot point, anyways...because if the Feds act anything like they acted with the I-35W and I-10 Twin Spans disasters, the Skagit River Bridge will be rebuilt at warp speed with 100% Federal funding. The people of Washington and Oregon will insure that after the first week of gridlock and delays.

Temporary replacement to open mid-June with 100% federal funding (so Jake, detouring may be a moot point for your trip).  Permanent replacement to open September or October with 90% federal funding.

With regards to low clearance signs -- which I think had been mentioned here, and also in the other thread in the Bridges section -- there aren't any.  Buuuut... the truck in question was 15'9".  The clearance at the center line is 18'0".  The clearance at the fog line is 15'6".  That's why the damage to the truck was only at the corner of the trailer, why it struck the bridge at such a critical point instead of just damaging one of the overhead beams (which had been struck many times before), and why people are blaming the width of the load moreso than the height.

(I know we had a thread about low clearence signs a while back with some more extreme examples, but if they were to post a sign for the 15'6" clearance, it would definitely the highest low clearance sign I'd seen in person.)

The more I read about the incident, the more sure I become that the fault rests solely on the truck and/or pilot car drivers.  If there was another truck passing him, then yes, that driver was being a dick, but isn't in anyway at fault.

Source for everything in the first and second paragraphs

[mtantillo]

If the other truck was passing, I don't think he was being a "dick". He was passing! Fast vehicles pass slow vehicles all the time. If the pilot car was doing its job, he would have told
The truck driver to stop until the other lane was clear.
Sure trucks don't like to slow down, but given a choice of slowing vs hitting a bridge, I would slow every time.

[kkt]

You don't live here, you probably do not know what is going on here.

I live here, and you're wrong.  Seattle area freeways are packed to the gills during rush hours.  There is no space to widen existing freeways or build new ones, so transit and encouraging carpooling has to be the answer.  Left-side HOV entrances and exits have their flaws, but they also have their benefits.  Putting an HOV lane on the right side has little to no benefit, as then HOV traffic has to compete with exiting/entering GP traffic.

- There is room to add lanes.  The valley freeway for example.  Prioritizing its widening & extension could remove trucks from the Southcenter Hill.   That would have been a better investment than the HOV flyovers at the bottom of the hill.

You mean you think the HOV lanes that were added a few years ago should have been general-purpose lanes?  Because it's not at all clear that there's room to add a fourth lane each direction now, and the interchange with 405 still leaves much to be desired.  And I don't think many trucks would be persuaded to divert to the Valley Freeway when I-5 is more direct.

- Left lane HOV/transit lanes slow the flow, and force slow buses to cross over multiple lanes to exit, further congesting the freeway.

Right lane HOV lanes are useless, they are full of entering and exiting traffic rather than the HOV vehicles they are supposed to serve.  The purpose of HOV vehicles is to allow buses to maintain their schedules even when it's congested.

A solution would be to only have HOV lanes during peak travel times and making them general purpose other times to cut down on congestion.

Dude, do you live here?  There's congestion about 14 hours a day.  There's no possibility of serving the entire population with single-occupancy vehicles.  Serving them through buses and carpools is about the only thing that's got a chance of improving the situation.  The express buses generally run full, and there are significant numbers of them.  In most of the Seattle area, there are more people in the HOV lanes than there are in the general-purpose lanes.

-   By putting ramps on the left side, you make the freeway safer, as now HOV traffic doesn't have to cross four lanes to exit.

But they do have to exit to the right most often. 

And transit is critically underfunded as well. 

Not in Washington.  We do not have underfunded transit.   You would be angry if you found out how subsidy per passenger it costs to ride Sounder.  It's an insane misallocation of resources.   

On a per-rider subsidy bases, the Sounder looks pretty bad.  But it's also small in absolute terms.  Maybe it should be cancelled, but don't be under any illusions that cancelling Sounder would free up enough money to do anything else meaningful instead.

Other transit in Washington State is seriously underfunded.  I'm a regular rider of King County Metro.  There have been runs cut from schedules, runs that were standing room only even before the cuts and are now turning would-be riders away almost every day.  Outside Seattle, things are even worse.

It's not like the bridge fell down because they decided to build the light rail out of gold instead.

The bridge wasn't replaced because the people in charge of this state think it is more important to spend large sums of money on public art and to over pay construction workers outside of the Puget Sound area in a payoff to the unions folks that help line their election coffers.  Some people in charge are hostile to the whole entire concept of automobiles.  WSDOT needs change, and it can only happen if people in this state finally dump the 29+ year one party rule.

Oh, bullshit.  Democrats are hardly unified, they're just better at building a big tent.  Lots of times there's enough Republicans in the state legislature to block things the Dems want to do.  This session, the Republicans have a working majority in the state Senate.  Tim Eyman's initiatives have done more to damage road funding than anything the Legislature has done.

Art?  Half of one percent for art?  You think that's what made the bridge fall down?

[kkt]

Sorry for the politics, I responded before reading to the end of the thread.

About the Skagit River Bridge, I had a nice drive to and from Bellingham this weekend.  I took a longer detour than the posted one, leaving I-5 at exit 221, Fir Island Road, going west to Best Road/Farm to Market Road, and going east again at WA-20.  Nice drive in pretty country, at the speed limit for those roads (40-50 mph).  It may be more congested once the work week starts again though.

[Landshark]

Bullshit.  Pretty sure every transit agency in the region has had massive service cuts in the past couple of years due to lack of funding.

Bull--it.  They have had some cuts due to mismanagement.  By service area, the Central Puget Sound area is one of the most linked in the country.   The bus system is fantastic.   

- WSDOT can't even get their ferry fares straight
- Sound Transit spends massive $ left and right on non-transit items
- Sounder commuter rail is a super expensive continually mega waste of $ that very few people use

This area is not underfunding transit.  You could make the case it is overfunded based on all the mismanagement of funds by those in charge. 

I could argue your other attempts to refute me, but I can tell pretty quickly when I'm not going to get through to someone.  Plus, like vtk said, this isn't the place.  It's just that one point that made me swear.

So one side can spout their opinion, but the other can't?  Saying transit is getting enough $, but isn't spending it wisely or not charging enough at the fare box is political, but saying it is underfunded is not?   Give me a break.


Post Merge: June 03, 2013, 02:24:21 AM

And there's the union blaming...

As expected, because a huge amount of the waste belongs on them.  Eliminating the prevailing wage would save millions.    Labor cartels are on their way out.  They are a corrupt relic of the past.   
Post Merge: June 03, 2013, 02:24:17 AM

You mean you think the HOV lanes that were added a few years ago should have been general-purpose lanes?

Hybrid lanes.  HOV during peak commute times, general purpose other times, and I would not have built the left lane i/e and transit stations.

And I don't think many trucks would be persuaded to divert to the Valley Freeway when I-5 is more direct.

The eventual extension will end at the Port of Tacoma.  It will not be much longer in distance and completely eliminates hills.  Trucks slowly climbing the South Center Hill is a major cause of congestion there.  It is why the state has wanted to extend 167.

Dude, do you live here?  There's congestion about 14 hours a day. 

For over 30 years.   Opening up the HOV lanes during non peak commute time would ease congestion.

There's no possibility of serving the entire population with single-occupancy vehicles.  Serving them through buses and carpools is about the only thing that's got a chance of improving the situation.

Chauffeured limousine lanes are a waste during non peak times.  Instead they create congestion by putting slower traffic on the far left.

Oh, bullshit.  Democrats are hardly unified, they're just better at building a big tent. 

Other than power and lining their allies pockets, it is not that unified.  Many are anti-car altogether.   The Democrats are also the ones that want to further gut road funding by reclassifying school buses.  They have been in power for almost 30 years now, they are to blame for mismanagement, misallocation of funds, and stupid design.  From the public art requirement to the prevailing wage to ignoring fare station corruption with the ferries, the Democrats have greatly hurt transportation funding in this state.

Lots of times there's enough Republicans in the state legislature to block things the Dems want to do.  This session, the Republicans have a working majority in the state Senate.

We need Republican governor before  there is any real change with WSDOT.  Also giving them control of all branches will make reform cleaner and easier. 

Tim Eyman's initiatives have done more to damage road funding than anything the Legislature has done.

Nonsense.   WA's gas tax is one of the nation's highest. 

Art?  Half of one percent for art?  You think that's what made the bridge fall down?

1%, and it is 1% too much waste.   

[myosh_tino]

Dude, do you live here?  There's congestion about 14 hours a day. 

For over 30 years.   Opening up the HOV lanes during non peak commute time would ease congestion.

If congestion is as bad as KKT says it is, then I would support 24/7 HOV lanes.  That concept does work... look at the HOV-lane setups in southern California where traffic is *always* bad.

You mean you think the HOV lanes that were added a few years ago should have been general-purpose lanes?

Hybrid lanes.  HOV during peak commute times, general purpose other times, and I would not have built the left lane i/e and transit stations.

Left lane entrances and exits for HOV traffic is a hell of a lot better than forcing HOV-lane users to cross 3-4 lanes of stop-and-go traffic to exit the freeway.  I'm kind of indifferent on the transit stations.

As for the rest of your post, the political discussion is not really appropriate for this forum as all it will lead to is a massive flame war and no one, and I mean NO ONE wants one of those... 

Edit: Removed comment asking how the HOV lane slows down traffic in the left lane.

[agentsteel53]

How do HOV lanes put slower traffic in the left lane?  Care to explain?

there are lots of times when the #2 lane (general access) is moving at 80mph, and the HOV is clogged up by some turd who thinks that the posted speed limit of 55 is to be obeyed to the letter.

[myosh_tino]

How do HOV lanes put slower traffic in the left lane?  Care to explain?

there are lots of times when the #2 lane (general access) is moving at 80mph, and the HOV is clogged up by some turd who thinks that the posted speed limit of 55 is to be obeyed to the letter.

Yeah, I thought about that after I made my post.  We have the same problem up here in northern California and it's worse when that "turd" is in an Express Lane trapping everyone behind him because it's illegal to cross the double-white lines (although that doesn't stop some drivers).

[kphoger]

How do HOV lanes put slower traffic in the left lane?  Care to explain?

there are lots of times when the #2 lane (general access) is moving at 80mph, and the HOV is clogged up by some turd who thinks that the posted speed limit of 55 is to be obeyed to the letter.

But does that actually affect the overall throughput of the highway?

[kkt]

You mean you think the HOV lanes that were added a few years ago should have been general-purpose lanes?

Hybrid lanes.  HOV during peak commute times, general purpose other times, and I would not have built the left lane i/e and transit stations.

When is peak commute times, then?  Most times of day I see the HOV lanes moving at 35-40, and occasional stop and go in the general purpose lanes.  Assuming drivers of HOVs are using sense, that means the HOV lanes are carrying more people.

On the Valley Freeway, the HOV lane is also HOT, so if you're rich and in a hurry you can pay for speed.  Also, many weekends there's no toll and the lane is general purpose.  Do you know if that depends on current traffic volume or is scheduled in advance?

And I don't think many trucks would be persuaded to divert to the Valley Freeway when I-5 is more direct.

The eventual extension will end at the Port of Tacoma.  It will not be much longer in distance and completely eliminates hills.  Trucks slowly climbing the South Center Hill is a major cause of congestion there.  It is why the state has wanted to extend 167.

And that project has reached the ROW acquisition stage.  Under a Democratic legislature and governor, amazing.

Dude, do you live here?  There's congestion about 14 hours a day. 

For over 30 years.   Opening up the HOV lanes during non peak commute time would ease congestion.

No, it would make it worse.  If there was no incentive to use HOVs anymore, people would desert the buses and use SOVs, generating much more traffic.

There's no possibility of serving the entire population with single-occupancy vehicles.  Serving them through buses and carpools is about the only thing that's got a chance of improving the situation.

Chauffeured limousine lanes are a waste during non peak times.  Instead they create congestion by putting slower traffic on the far left.

If traffic in the HOV lane were really going slower than the general purpose lane adjacent, HOV traffic would leave the HOV lane and drive in the general purpose lane, wouldn't they?  Isn't that what you'd do if the lane next to you were moving faster and you had the option to get into it?  It's not like there's any lane discipline shown on urbanized freeways in Washington...

Oh, bullshit.  Democrats are hardly unified, they're just better at building a big tent. 

Other than power and lining their allies pockets, it is not that unified.  Many are anti-car altogether.

Please cite a specific Washington State elected Democrat who has spoken out for the elimination of cars.

Pure politics deleted...

Nonsense.   WA's gas tax is one of the nation's highest. 

Yeah, that's what happens when there's no construction or maintenance money coming from vehicle registration fees and no personal income tax and a business tax as full of holes as swiss cheese.

Art?  Half of one percent for art?  You think that's what made the bridge fall down?

1%, and it is 1% too much waste.   

http://www.nasaa-arts.org/Research/Key-Topics/Public-Art/State-Percent-for-Art-Programs.php#WA
Funding Source

Half of 1% of capital appropriations for new construction...

[agentsteel53]

If traffic in the HOV lane were really going slower than the general purpose lane adjacent, HOV traffic would leave the HOV lane and drive in the general purpose lane, wouldn't they?  Isn't that what you'd do if the lane next to you were moving faster and you had the option to get into it?  It's not like there's any lane discipline shown on urbanized freeways in Washington...

must be a SoCal thing only to have restricted access to the carpool lane.  you can only enter/exit about once every 1-3 miles.

[kkt]

If traffic in the HOV lane were really going slower than the general purpose lane adjacent, HOV traffic would leave the HOV lane and drive in the general purpose lane, wouldn't they?  Isn't that what you'd do if the lane next to you were moving faster and you had the option to get into it?  It's not like there's any lane discipline shown on urbanized freeways in Washington...

must be a SoCal thing only to have restricted access to the carpool lane.  you can only enter/exit about once every 1-3 miles.

Now I think of it, the Valley Freeway's HOV lanes are like that.  But I-5 and 405 and 90 are enter/exit anywhere.

[mtantillo]

If traffic in the HOV lane were really going slower than the general purpose lane adjacent, HOV traffic would leave the HOV lane and drive in the general purpose lane, wouldn't they?  Isn't that what you'd do if the lane next to you were moving faster and you had the option to get into it?  It's not like there's any lane discipline shown on urbanized freeways in Washington...

must be a SoCal thing only to have restricted access to the carpool lane.  you can only enter/exit about once every 1-3 miles.

Now I think of it, the Valley Freeway's HOV lanes are like that.  But I-5 and 405 and 90 are enter/exit anywhere.

Other places have access limited HOV lanes.  Lanes in Connecticut (84 and 91), New York (LIE), Georgia (85), and Ontario (QEW and 403 are the ones I know of, there might be more). 

[kphoger]

Dallas—Fort Worth, also.

[NE2]

I'm waiting for Landshark to blame atheists. If that bridge had been properly blessed...

[J N Winkler]

Historical information:  the Skagit River Bridge was built initially as part of Primary State Highway No. 1 with a plans approval date of July 29, 1954.

[kkt]

From the Seattle Times today, http://seattletimes.com/html/localnews/2021075677_bridgecollapselowxml.html

7 low highway bridges hold similar risks to Skagit span

Washington state has seven other highway bridges with clearances as low as the I-5 Skagit River bridge, where an overheight load destroyed one of four spans last week. That fact suggests that without tougher oversight of cross-state hauling, the same kind of accident could happen again.

By Mike Lindblom and Cheryl Phillips

Seattle Times staff

Washington state has seven other highway bridges with clearances as low as the Interstate 5 Skagit River bridge, where an overheight load destroyed one of four spans last week.

That fact suggests that without tougher oversight of cross-state hauling, the same kind of accident could happen again.

These seven bridges measure 14 feet 6 inches or less at their lowest overhead clearance. They are "fracture-critical,"  meaning a single broken beam could cause collapse.

They were built from 1927 to 1949 except for a short bridge at the Tacoma ferry terminal, built in 1994. Yet another old and low-clearance bridge, over Ebey Slough on Highway 529 near Marysville, is being replaced with a new crossing this spring.

These are by no means the only bridges that can get hit.

The state Department of Transportation said last weekend there were 21 known hits involving trucks on state bridges last year – including at least once on the Skagit River bridge – as well as 24 in 2011 and 14 in 2010.

A Whatcom County bridge near Ferndale was closed and repaired last year when an oversize excavator on a trailer hit five beams.

Washington state allows haulers to obtain oversize-load permits online, unless the load is 16 feet or taller.

The load that struck the Skagit bridge was estimated at 15 feet 9 inches in its state permit to Mullen Trucking of Alberta, which was taking an empty case for a giant drill south to Vancouver, Wash.

The Skagit bridge also was hit northbound last year, prompting a special inspection.

Besides the eight very low-clearance bridges, 52 more bridges are between 14 feet 6 inches and 15 feet 6 inches at their lowest point – so conceivably they could have been hit by that drill case.

When the load struck the Skagit River bridge, it sent one of the spans plummeting to the water, along with two vehicles. The three people inside the vehicles weren't seriously injured, but the bridge will be closed for weeks while a temporary fix is installed.

To clear the bridge, driver William Scott would have needed to move into the left lane, with a clearance of 17½ feet to 18 feet. The right lane measures only 15 feet 6 inches at the white fog line.

"There are hundreds of oversize permits sold per day,"  said Jim Tutton, vice president of the Washington Trucking Association, so overheight trucks shifting lanes would not be unusual.

But Scott told investigators he was passed by another truck on the bridge, which would have prevented him from moving over. He also said he heard no warning from the pilot car in front of him, according to Deborah Hersman, chairwoman of the National Transportation Safety Board. The NTSB expects to interview the pilot-car driver Wednesday.

By state law, the pilot car must have a pole 3 to 6 inches taller than the load, to detect possible dangers.

The federal investigation is pointing up some potential gaps in state regulations:

- There is no state requirement to post bridge clearances unless they are 14 feet 4 inches or less, and this bridge wasn't posted, said Hersman. Truckers can find clearance information for all bridges on a state website.

- Washington has no requirement for the truck to use a pilot car in the rear, which might have deterred passing what was both a high and a wide load.

Devices are available to reduce risks of an overhead hit; light beams can trigger an alarm if a tall load breaks the beam.

The Mullen Trucking load did trip such an overheight warning at or near a weigh station, but that "was no cause for alarm"  since the truck was labeled overheight, said State Patrol spokesman Bob Calkins. "The company has a decent safety record; they come through that port of entry regularly,"  he said.

Jerry Ely, a Skagit Valley trucker who has been urging NTSB personnel to focus on the pilot car, said, "They [DOT] need to start making new laws and cleaning up their act in this state."

Harvey Coffman, state bridge-preservation engineer, said that as of Monday he hadn't yet looked into any possible reforms because he is working full time on designing the replacement span so traffic can resume.

Truckers can self-apply for a permit online, for $10 in the case of last week's drill load.

"Last year we issued 135,000 permits. Right there, that gives you the value of truck freight that comes through the state,"  said Lars Erickson, DOT spokesman in Olympia.

The State Patrol's commercial-vehicle enforcement unit last year issued 251 citations or warnings statewide for loads that either lacked or violated an overheight permit, said Lt. Dennis Bosman.

Tutton, from the truckers group, said: "Everybody involved in the permit process, from the truckers, the pilot-car drivers, the companies and the people that issue permits for the DOT, need to really take explicit care in identifying the size of the load, so they know exactly what happens."

Mike Lindblom: 206-515-5631 or mlindblom@seattletimes.com
Cheryl Phillips: 206-464-2411 or cphillips@seattletimes.com

[Brandon]

^^ Seems like a potential systemic failure here.

1. A lack of posting for bridges less than 16 feet in clearance.  IIRC, interstate highway bridges need 16 feet of clearance.
2. A lack of a requirement for a trailing pilot car to prevent dangerous passing maneuvers such as the truck passing the oversized load on the bridge.

I can already see some of the NTSB's recommendations based on the systemic failures here.  I'll bet they include:

1. Posting of all clearances less than 16 feet in height.
2. The use of trailing pilot vehicles for oversized loads.
3. The replacement of similar fracture-critical bridges.

[myosh_tino]

I found this particularly interesting...

- There is no state requirement to post bridge clearances unless they are 14 feet 4 inches or less, and this bridge wasn't posted, said Hersman. Truckers can find clearance information for all bridges on a state website.

... because I've seen low clearance signs (W12-2) with heights of more than 15 feet posted on freeways around the San Francisco Bay Area.  I was surprised that Washington only requires these signs for clearances of a little more than 14 feet or less particularly when Interstate standards require 16 foot clearances.

Digging around the California MUTCD, I found that California requires low clearance signs (W12-2) for all clearances of 15 feet 6 inches or less.  The vanilla MUTCD states that the low clearance signs are required when the clearance is "less than 12 inches above the statutory vehicle height."  Does the statutory vehicle height vary state-to-state?

[J N Winkler]

^^ Seems like a potential systemic failure here.

Yup--that is what I have thought from the very beginning.

I can already see some of the NTSB's recommendations based on the systemic failures here.  I'll bet they include:

1. Posting of all clearances less than 16 feet in height.

I don't think that will happen, because (1) it is likely to increase greatly the number of bridges for which clearance signing has to be provided and maintained (including updates to reflect changes in clearance as a result of resurfacing projects), and (2) it is unclear from the information presently available whether clearance signing at the Skagit River Bridge would have prevented the accident.

2. The use of trailing pilot vehicles for oversized loads.

I don't see this one happening, largely because a trailing pilot vehicle moving to straddle a lane line to choke off overtaking maneuvers can itself cause serious accidents.

3. The replacement of similar fracture-critical bridges.

Agreed, but the NTSB will never mark this "Immediate Action" (as they do with some of their recommendations) owing to the costs involved.

After studying the permit which was issued to the trucking company (which includes "Route OK - WSDOT Does Not Guarantee Height Clearances" disclaimers rather than actual clearances) and the vertical clearance card for the Skagit River bridge, here is another recommendation I would expect to see from the NTSB:

*  When an overdimensional permit is issued that requires the load to follow an agreed routing, all of the clearances associated with each bridge on the route shall be explicitly specified in the permit.  (These clearances will include not just the posted clearance, if any, but also the measured clearance at other points open to motor vehicle travel; there were eleven of these on the Skagit River Bridge.)  Where one or more of these clearances is less than the height of the load, they shall be printed in double-size type, the clearance listing for the bridge as a whole shall be enclosed in a box with a thick black border and "!" in a diamond next to it, and the bridge clearance card shall be included as an annex to the permit.

[myosh_tino]

I don't think that will happen, because (1) it is likely to increase greatly the number of bridges for which clearance signing has to be provided and maintained (including updates to reflect changes in clearance as a result of resurfacing projects),

If California can sign all clearances less than 15 1/2 feet given how extensive California's road network is, then I can't see why Washington couldn't do the same for it's 59 bridges.

(2) it is unclear from the information presently available whether clearance signing at the Skagit River Bridge would have prevented the accident.

I believe this could have been prevented.  If Washington had followed California's standards, there would have been a W12-2 sign warning of a 15' 6" clearance ahead (the height posted is at the lowest point).  Assuming the trucker knew his load was 15' 9", he would have realized that his load was too tall and would have to find an alternate route.

[J N Winkler]

I don't think that will happen, because (1) it is likely to increase greatly the number of bridges for which clearance signing has to be provided and maintained (including updates to reflect changes in clearance as a result of resurfacing projects) . . .

If California can sign all clearances less than 15 1/2 feet given how extensive California's road network is, then I can't see why Washington couldn't do the same for its 59 bridges.

I wrote the part you quoted in response to a suggestion that the threshold for clearance posting should be sixteen feet, not fifteen and a half.  If WSDOT copied Caltrans' clearance posting standard, then the cost would indeed be limited.  My concern is that we might be dealing with just 59 bridges under 15' 6" but over 1000 between 15' 6" and 16'.

It was a pretty major undertaking for Caltrans to post clearance signs--if memory serves, the current standard was adopted around 2003, and as a result at least two (I think three) major signing contracts had to be let just for clearance signing on bridges in District 7 (Los Angeles).  I would expect the NTSB to look closely at whether this clearance signing did in fact reduce the frequency of bridge strikes in California.  Did it?

. . . (2) it is unclear from the information presently available whether clearance signing at the Skagit River Bridge would have prevented the accident.

I believe this could have been prevented.  If Washington had followed California's standards, there would have been a W12-2 sign warning of a 15' 6" clearance ahead (the height posted is at the lowest point).  Assuming the trucker knew his load was 15' 9", he would have realized that his load was too tall and would have to find an alternate route.

Actually, no, the sign would not have said 15' 6"--it would have said 14' 6" (clearance at the northbound curbline, which is the point of lowest vertical clearance).

The trucker did know his load was 15' 9".  I presume the pilot car driver also knew it was 15' 9".  That height is clearly stated on the permit and the information would have had to be supplied by the trucker (assuming "self-issue" means "self-report").  The NTSB investigation will have to sort out how thoroughly the trucker and pilot car company investigated the clearances on the route, and what information was made conveniently available for them to do that.  (WSDOT apparently has an online clearance database which truckers could consult, but I don't know if it has clearances to the same detail as the bridge clearance cards.)

My concern here is really confirmation bias, which would make itself evident in a chain of reasoning like this:  "This bridge is signed for 14' 6".  My load is 15' 9".  However, I am following this route by agreement with the pilot car company, after we both studied the clearances along the route, and we would not have routed under this bridge if there was not a way to haul a 15' 9" load through it.  So I will keep on going."

[kkt]

1. A lack of posting for bridges less than 16 feet in clearance.  IIRC, interstate highway bridges need 16 feet of clearance.

This site: http://safety.fhwa.dot.gov/geometric/pubs/mitigationstrategies/chapter3/3_verticalclearance.htm says the minimum clearance can range from 14 to 16 feet.  So IMHO, first on your list of systematic failures should be a minimum clearance that isn't the same from state to state.  Truckers learn to drive trucks in a state where everything under 16 feet is posted, then drive through some other state, and bam.  Literally.  The purpose of interstate standards is... well, I expect I'm preaching to the converted here.

[kphoger]

2. The use of trailing pilot vehicles for oversized loads.

I don't see this one happening, largely because a trailing pilot vehicle moving to straddle a lane line to choke off overtaking maneuvers can itself cause serious accidents.

Side question:

Are rear pilot vehicles actually legally allowed to straddle the line in order to prevent others from passing?  I was once on I-235 southbound behind a slow-moving truck hauling a wind turbine blade, and the truck and pilot car basically straddled the lane line the entire length of the highway.  I eventually just passed the two of them by straddling the inside shoulder lane.  Obviously, my maneuver was illegal because I drove on the shoulder.  But I've wondered ever since then what the legal status of pilot cars' maneuvers is.  And, if they have legal protection, are there any limits on it?

[mtantillo]

I once had a truck that was not marked as oversize/over height on the Outerbridge Crossing do that, presumably because he didn't want to be bothered staying within his lane. That can be considered reckless driving/obstructing the highway, and is definitely illegal, not to mention, not to mention, overly aggressive driving. If you aren't over width, you can fit within the lane.

Now a genuinely over width vehicle should not have to do this on most stretches, they can just straddle the right lane, right shoulder. But in construction zones or on narrow bridges, the pilot car in back will come out and temporarily prevent passing while on the narrow structure.  This is more reasonable because there is a need and it is over a short distance.  I can't see why a truck would need to take up multiple lanes if there is a shoulder available. 

In the case of the I-5 bridge, preventing passing would have been prudent because of lack of shoulders. Riding the left lane would have been prudent to avoid hitting the bridge, and a polite driver would have increased his speed to avoid others trying to pass on the right. But in the absence of a pilot car holding back those tying to pass, I doubt cars would voluntarily not pass. The truck has the oversized load, the onus is on him to keep other vehicles out of the way if he needs more space than the lanes provide.