Another bit of bad news - Hopefully Now..
> Hopefully now, The washington state legislature will get off their hinny and pass through the Columbia River Crossing legislation and funding package that they are sitting on to get that I-5 bridge done.....
I'd like to respond to this in detail but it would qualify as P&R. Let me just say that if simply replacing the bridge was all that was proposed it would be done already.
How A Single Oversize Load Collapses A Bridge
The above link should bring up a picture of the span next to the collapsed span (photo 31 of 43 after a pause). Take a look at the third vertical member on the right side. It is damaged and kinked about 1 foot. Above it the horizontal brace has a piece chopped out on the curve to the vertical.
The load was a part of a drilling rig 12' wide and 14' high, and was of steel. The lanes appear to be 14' wide with no shoulder. The truck carrying the load had a permit and an escort. The Jersey barrier along the side appears close enough that an overhanging side load could contact the vertical steel. The vertical clearance was 14.6' but that most likely was not measured at the edge of the traveled lane.
It is reported that the top right corner of the load caught the cross brace. On the collapsed span that would be at the second vertical. Since the collapsed span did not have a vertical at the end per the posted photo, the damage would be similar to that visible on the third vertical in the photo link. With the load being of substantial steel and the truck at speed the contact would have been sufficient to kink/tear the horizontal and/or kink/tear the vertical. The vertical in this position carries no load but braces the top chord. Once the top chord is no longer braced in the middle it has an unbraced length twice the design. That means it would take a lot less than the design load to collapse it. If the top chord became kinked it would hasten the collapse. The dead weight of the bridge is sufficient to complete the collapse.
Paul in PA
Surveillance Video Of I-5 Bridge Collapse
An offsite surveillance camera shows the collapse.
There should also be Homeland Security cameras on the bridge, whether the video gets released is another story.
Paul in PA
Permits And Clearance
"State officials approved the trucking company to carry a load as high as 15 feet, 9 inches, according to the permit released by the state. However, the southbound vertical clearance on the Skagit River bridge is as little as 14 feet, 5 inches, state records show. That lowest clearance is outside of the bridge's vehicle traveling lanes, Transportation Department communications director Lars Erickson said Friday. The bridge's curved overhead girders are higher in the center of the bridge but sweep lower toward a driver's right side."
"The bridge has a maximum clearance of about 17 feet, but there is no signage to indicate how to safely navigate the bridge with a tall load."
The high/wide load can easily extend outside of the traveling lane.
As to higher clearance in the center, I have crossed bridges that are "signed" to keep vehicles out of the right lane.
If the load was any where near the permitted 15'9" and in the truck in right lane contact was almost a certainty.
Was the escort vehicle fitted with a pole?
I saw a broadcast portion of the above posted video that points out the escort vehicle. It was well ahead of the truck and even with a pole the load driver may not have seen any pole contact.
Paul in PA
Permits And Clearances
"State officials approved the trucking company to carry a load as high as 15 feet, 9 inches, according to the permit released by the state. However, the southbound vertical clearance on the Skagit River bridge is as little as 14 feet, 5 inches, state records show. That lowest clearance is outside of the bridge's vehicle traveling lanes, Transportation Department communications director Lars Erickson said Friday. The bridge's curved overhead girders are higher in the center of the bridge but sweep lower toward a driver's right side."
"The bridge has a maximum clearance of about 17 feet, but there is no signage to indicate how to safely navigate the bridge with a tall load."
The high/wide load can easily extend outside of the traveling lane.
As to higher clearance in the center, I have crossed bridges that are "signed" to keep vehicles out of the right lane.
If the load was any where near the permitted 15'9" and in the truck in right lane contact was almost a certainty.
Was the escort vehicle fitted with a pole?
I saw a broadcast portion of the above posted video that points out the escort vehicle. It was well ahead of the truck and even with a pole the load driver may not have seen any pole contact.
Paul in PA
