Why This Bridge Disappeared in Seconds? - Sunshine Skyway Bridge

Ajouté : 2026-05-30

[00:00:00]A journey over the beautiful [music] and curvy Sunshine Skyway Bridge was any motorist's dream.

[00:00:05]However, on May 9th, 1980, early morning, a strange sequence of collapses and what the car passengers experienced was Rewind just 10 minutes back. This ship, which is approaching the bridge, is supposed to pass between the main piers.

[00:00:24]Unfortunately, what will happen if this pier is not passed? Obviously, this junction has to go down.

[00:00:34]What happens afterward?

[00:00:36]Look at the strong hinges at the other end. Can they resist the bridge failure?

[00:00:43]The biggest surprise is in this photograph. You can see both the columns are collapsed, but the base structure is intact. How can a ship collision damage both the columns without damaging the base? The answer lies in the way the captain navigated the ship. These buoys are crucial for the captain. Navigating the ship under the bridge was a difficult task and still is.

[00:01:06]Look at the sharp turn the captain had to take.

[00:01:09]The most crucial buoys in this whole task are 1A and 2A.

[00:01:13]The captain is all prepared to navigate the ship from Mullet Key Channel to Cut A Channel.

[00:01:18]But, a sudden burst of rain and wind caused the captain to lose visual on these two most crucial buoys.

[00:01:26]The ship was still on radar.

[00:01:28]Unfortunately, the wind strength increased further and the ship disappeared from radar, too. This is something every sailor is terrified of.

[00:01:36]A microburst of adverse effects at the most crucial moment.

[00:01:40]He even ordered the ship's leader to be ready to drop anchors.

[00:01:44]The captain was obviously making clever decisions at this time.

[00:01:48]The captain's only hope was the lookout at the starboard side.

[00:01:52]The lookout reported a sighting of a buoy to the captain, but with no details of angle or distance. the lookout had a brief sighting of buoy 2A, and this was the position of the ship at that moment.

[00:02:03]The ship is outside the Mullet Key Channel. With no information of angle and distance, what the captain perceived was this position. Ship's bow 15 m from buoy and perfectly inside the Mullet Key Channel.

[00:02:17]Based on this perception, the captain decided to turn the ship. At 7:31 a.m., he even reduced the engine speed further.

[00:02:27]Please pause the video here to analyze these two situations.

[00:02:31]If the presumed position of the ship was correct, this is the effect of the ship's turning. In reality, the starting position was totally [music] different, and most importantly, the ship was at an angle. You know what will happen if the ship is angled.

[00:02:46]It will change [music] the course of travel completely.

[00:02:49]You can even notice the captain took the right amount of turn. Due to the wrong starting, the ship was at an offset from the channel. This offset kept on increasing as the ship approached the bridge. Now, let's pause the video here and analyze an imaginary condition.

[00:03:05]What if the ship was straight at the beginning?

[00:03:08]To answer this, you just need to rotate the ship path like this.

[00:03:13]Wow, the ship is perfectly between the main piers of the bridge.

[00:03:18]Anyway, this didn't happen, and at roughly one ship length away, the crew was terrified to see a bridge pier in front of the ship. It was too late. The captain immediately ordered full power [music] and reverse of the engine. The anchors were also quickly released and began dragging the ship in the shallow water.

[00:03:38]The ship speed was slightly reduced.

[00:03:41]A ship with such a huge [music] momentum cannot be stopped easily.

[00:03:46]At 7:34 a.m., the ship slammed into one of the main piers of the bridge.

[00:03:52]To understand the nature of this impact, let's rewind this crash in the top view.

[00:03:59]It was not a head-on collision.

[00:04:02]The ship was angled.

[00:04:05]And the ship's starboard side hit column one of the pier. The starboard side of the ship had a huge impact with the protection barrier.

[00:04:13]This portion being too strong didn't move or develop any crack.

[00:04:18]Look at the geometry of the bridge pier.

[00:04:20]It is rugged.

[00:04:21]First, a protection barrier. After that, piles traveling through the ocean bed until they reach the hard strata.

[00:04:29]The strong protection barrier deformed the ship's body, and with a reduced speed, it moved forward and hit column two as well.

[00:04:37]Eventually, column two as well was destroyed.

[00:04:41]With this hit, the ship lost all momentum and came to arrest.

[00:04:46]If it were a head-on collision, what would have happened?

[00:04:49]We already know about the strength of the protection barrier. [music] In this case, the first column would definitely collapse.

[00:04:56]Most importantly, the ship's front region would have suffered heavy damage, possibly cracks and water leakage, too.

[00:05:04]But there was no way the ship would hit the second column. Even though slightly [music] twisted, the bridge would have stayed upright, and tragedy could have been avoided. Unfortunately, the pier of the [music] bridge destroyed was an important structural element of the cantilever bridge known as the anchor pier.

[00:05:23]The cantilever bridge has an interesting science behind it.

[00:05:27]The bearing on the main piers are crucial. If you observe an image of a cantilever bridge during construction, you can see two cantilevers approaching each other.

[00:05:37]These are the main piers of the bridge.

[00:05:39]These cantilevers are not permanently fixed with the main pier.

[00:05:43]Instead, they are connected with the main pier via a rocker bearing.

[00:05:48]This structure is obviously not stable.

[00:05:51]What makes them stable is the connection between the cantilever sections, the suspended arm.

[00:05:57]The connection here is interesting. It's a type of hinge that allows for slight bending of the bridge and in the meantime maintaining the stability of the bridge. The gap caused by this connection is filled with finger expansion joints.

[00:06:12]When a vehicle weight acts on this bridge, the bridge will flex slightly down.

[00:06:17]You may observe the role of rocker bearings and hinges during this flex.

[00:06:21]The big question is, what will happen to this bridge without the support from this pier?

[00:06:26]To understand this, I would like to introduce you to professional-grade mechanical design software. A simplified model of this bridge was built using 3DEXPERIENCE SOLIDWORKS for makers, a new affordable way to use SOLIDWORKS for personal projects and more, now available for just $36 US per year.

[00:06:45]Check out the discount link in the description below or visit solidworks.com/lessex to It is obvious that without the support of the pier, the bridge will bend as shown.

[00:07:02]What about the hinges on the other side?

[00:07:04]The SOLIDWORKS simulation predicts that the hinge will go up. It's counterintuitive, right?

[00:07:11]Due to the lost support, the hinge wants to move up.

[00:07:15]The question is, can the hinges resist this upward motion?

[00:07:20]No. The load the hinges had to carry was tremendous and the hinges broke. This portion of the bridge disappeared into the water.

[00:07:30]Without the support of the right portion, a cantilever bridge is not stable.

[00:07:35]The left portion of the bridge also collapsed eventually.

[00:07:40]The Sunshine Skyway Bridge was in fact a pair of bridges which are parallel. The ship didn't hit the other bridge and it remained intact.

[00:07:50]The first vehicle to fall into the water was the 1974 blue Ford Courier pickup truck driven by Wesley McIntyre.

[00:07:59]When he was in the middle of the bridge, he felt the pickup started to bob up and down.

[00:08:04]While the pickup was in the descending phase of the bridge, the roadway effectively vanished with His truck fell approximately 46 m.

[00:08:15]Immediately after McIntyre's truck fell, the other vehicles followed.

[00:08:19]The next was a Greyhound bus.

[00:08:22]Because of the blinding rain, the driver could not see that the bridge was gone until it was too late.

[00:08:29]Five other cars followed, essentially driving into a hole in the storm.

[00:08:35]The famous yellow Buick Skylark driven by Richard Hornbuckle was next in line.

[00:08:40]He managed to slam on the brakes and skidded to a stop just 14 in from the jagged edge.

[00:08:47]The collapse resulted in the deaths of 35 people.

[00:08:51]Only one person survived the fall from the bridge, the first car which fell into the ocean.

[00:08:57]After the 150-ft fall, his truck struck the hull of the MV Summit Venture before sinking into the water. He managed to crawl out of his window and was pulled from the water by the ship's crew.

[00:09:10]The story of Captain John Lerro, the harbor pilot at the helm of the MV Summit Venture during the 1980 Sunshine [music] Skyway Bridge collapse, is often described by historians as a collision of guilt. Immediately following the disaster on May 9th, 1980, Lerro faced intense public scrutiny and the suspension of his pilot license.

[00:09:31]However, the legal outcomes were in his favor.

[00:09:35]After a 2-week trial, a judge ruled that Lera was not negligent. The disaster was officially deemed an act of God due to the sudden freak microburst storm that blinded the ship's radar and navigation.

[00:09:49]His state pilot license was eventually returned to him, and he briefly returned to work on the water. Less than a year after the collapse, John Lera was diagnosed with multiple sclerosis.

[00:10:00]A cruel illness that forced him to abandon the career he'd spent a lifetime building.

[00:10:07]Stripped of the sea and the work [music] he loved, Lera chose not to turn inward.

[00:10:16]>> [music] >> Instead, he spent the remainder of his life trying to transform tragedy into purpose. [music] He taught maritime cadets, warning them with hard-earned [music] wisdom, "If you misjudge, you'll have hell to pay."

[00:10:33]>> [music] >> He also became a counselor for convicts and victims of crime, hoping that his own suffering might help others find a path toward healing. Those closest to him, including his lawyer and long-time friends, [music] believed the extreme stress and trauma of the disaster accelerated the onset of his disease.

[00:10:52]>> [music] >> Lera lived with profound survivor's guilt. He once reflected, "It was all over [music] in two minutes, and those two minutes are all that mattered."

[00:11:02]For him, time never softened the weight of the 35 lives lost. He carried that burden for the rest [music] of his life.

[00:11:10]As his health steadily declined, he was ultimately forced to retire completely from maritime work.

[00:11:17]>> [music] >> John Lera passed away on August 31st, 2002, at the age of 59 due [music] to complications from multiple sclerosis.

[00:11:26]As author Bill DeYoung later wrote, "John went through hell. He felt guilty for the rest of his life.

[00:11:33]The MV Summit Venture actually suffered minor damage compared to the catastrophic destruction it caused to the bridge. The ship was repaired shortly after the accident, while the bridge was estimated at $30 million at the time, the repairs for the Summit Venture cost approximately $1 million. The work primarily involved was patching and reinforcing the crumpled steel on the bow. They also had to repair anchor systems that were deployed and damaged during the desperate attempt to stop the ship. The ship returned to service later in 1980 and continued to operate under its original name, MV Summit Venture, for over a decade.

[00:12:11]In fact, with a change of ownership and name, the ship continued its service for 30 more years.

[00:12:18]On November 9th, 2010, while sailing off the coast of Vietnam, it began taking on water and sank.

[00:12:27]Fortunately, all 26 crew members were rescued.

[00:12:31]The collapse of the Sunshine Skyway Bridge was a watershed moment in civil engineering, leading to a complete overhaul of how bridges are designed to withstand ship impacts. When they inaugurated new bridges in 1987, the authorities and engineers applied several critical lessons.

[00:12:48]The original Sunshine Bridge was the vital connecting link between St. Petersburg to [music] the Terra Ceia in Florida, with a total length of 6.7 km.

[00:12:58]This image illustrates the position of the new bridge. Note that they didn't have to demolish the entire old bridge for the construction of the new bridge.

[00:13:08]This portion of the approach ramp became a part of the new bridge.

[00:13:12]The most significant lesson while constructing the new bridge was that a bridge's support piers must be physically isolated from ship traffic.

[00:13:20]In 1980, there was nothing between the ship and the bridge pier. Engineers surrounded the new bridge's main piers with 36 massive concrete dolphins.

[00:13:30]These are circular rock-filled structures that act as bumpers.

[00:13:35]If a ship veers off course today, it will strike a sacrificial stone and concrete dolphin, grounding the ship long before it can touch the bridge itself.

[00:13:45]The original bridge had a relatively narrow opening for ships. It was 244 m, which left very little margin for error.

[00:13:53]For the new bridge, this clearance is 366 m. Engineers moved away from the old cantilever steel truss to cable-stayed bridges.

[00:14:02]The cantilever bridge works on balance.

[00:14:05]When one major piece was hit, a large section of the roadway became unstable and fell.

[00:14:11]Cable-stayed bridges have high redundancy.

[00:14:16]Moreover, the old bridge was located in a spot where the shipping channel took a difficult turn.

[00:14:22]The new bridge was built about half a mile east of the original site.

[00:14:26]This repositioning allowed the shipping channel to be straightened, reducing the number of complex maneuvers a pilot has to make while passing under the span.

[00:14:36]>> You can enjoy the construction sequence of the original Sunshine Skyway Bridge, the cantilever bridge, behind me.

[00:14:44]>> [music] >> It's fun to watch the protruding cantilever arms.

[00:14:50]Now, they're going to close this gap >> [music] >> using the suspended arm.

[00:14:57]>> The original Sunshine Skyway Bridge was a beloved icon of Florida's mid-century growth.

[00:15:03]The bridge had a very abrupt steep incline that peaked at 46 m.

[00:15:09]On clear days, tourists and thrill-seekers loved the ascent.

[00:15:14]For daily commuters, the steepness created an optical illusion where the road seemed to disappear into the sky, making it feel like you were driving off a cliff until you reach the crest.

[00:15:26]The bridge offered a spectacular view from its very top.

[00:15:31]>> Hi, the use of SolidWorks was crucial in understanding how the Sunshine Bridge behaved once one of its piers lost.

[00:15:39]Please check out the description and check this amazing software SolidWorks for makers.

[00:15:45]Take care. Bye-bye.