this post was submitted on 16 Aug 2026
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It's not as difficult as you might think. Or, more precisely, it's a lot more difficult to destroy a bridge than you might expect. Look at how much trouble Ukraine has had trying to keep the Kerch Strait bridge out of commission. Or look at the hundreds of bombing runs the US did in Vietnam to try and knock out one stupid bridge.
It's easy enough to temporarily shut a bridge down. Bombing its road deck is pretty easy. The deck is usually exposed to the sky, so bombs can be dropped right on it from above. And the deck is thin enough to be fairly vulnerable to bombing.
The problem is that bombing a bridge deck doesn't actually destroy the bridge. At best you create a hole in the bridge deck a meter or two across. That can shut a bridge down temporarily, but it doesn't actually damage the bridge's structure. To repair the deck you do something like:
This can be done in a day or two. And on a multi-lane-bridge, traffic can continue to flow around the bomb site at reduced capacity.
If you actually want to destroy a bridge, you can't just hit a random spot on the bridge deck. If it's a big truss bridge, a direct hit on a key truss member could cause the entire bridge to collapse. But those are very precise targets to hit. And if it's just a bridge deck sitting on beams sitting on piers, the only way to destroy the bridge will be to knock out the support piers.
The problem with destroying them is that bridge piers are both hard to hit and extremely resilient. They're protected from above by the bridge deck, so to hit them you'll have to glide a bomb in horizontally. And even if you manage to hit them, they're utterly massive. They have to support the entire weight of the bridge above. Plus they're often directly in a river's channel. This means they're built to survive the forces of water current and ice collision if the bridge is in a temperate climate. Plus they're built extra thick to resist the corrosive effects of the river water. Now, if you do actually manage to knock out a support pier, replacing it will be a nightmare. But that's a very difficult thing to do.
It's actually a lot more difficult to destroy a bridge than people realize. Knocking a hole in a bridge deck is easy. But bridge decks are easily and quickly repairable.
This is kina dumb. Seeing how they can precisely land a missile on a car going 100kph on the other side of the world.
And yet, your gut feelings are incorrect. As has been clearly demonstrated by the well documented difficulties militaries have in keeping bridges down through air power alone. But sure, tell the literal structural engineer you know more about bridges than she does.
Now that we caught an actual structural engineer, here's a question from a fellow engineer (but the wrong kind to know this):
I'm thinking of the top of my head that the forces and dynamics of a suspension bridge are very different from those of a more traditional bridge and thus that if the actual cables holding it are blown up at the anchor points, the whole suspended span just brings itself down as a whole leaving just the pillars.
Further, suspension bridges tend to be used for longer lengths of bridge were you can't really have pillars in the middle (in this example in the US, the suspended spawn being there so that ships can cross under the bridge)
Note/Dislaimer: the information here is purely hypothetical and educational, discussing the limits of Air Power as a means of severing enemy transportation links. The Golden Gate Bridge is used as a familiar example when discussing the vulnerability of suspension bridges. But the author of this post has zero desire or intention to damage the infrastructure of the US or any other country. Nothing in this post should be taken as a threat or warning of any kind.
Your instincts are correct. The forces are very different. If one of the main cables on a suspension bridge is severed, the entire bridge deck will come down. You would be able to reuse the towers, foundations, and maybe some of the vertical cables supported by the main cable that wasn't hit, but repairing such damage would be similar in difficulty to rebuilding the bridge from scratch. Demolition and restoring that bridge deck probably represents about 50% of the work of building a whole new bridge from scratch.
However, actually severing one of the main cables is lot more difficult than you might think. They're not a giant rod of solid steel; they're thousands of individual pencil-sized wires bundled together. At the anchorages, these individual wires spread out and embed themselves into a giant block of concrete. Here are the Golden Gate Bridge's anchorages under construction.
Those steel elements are only a portion of the total, and after they were built, the entire volume was filled with concrete. The Golden Gate Bridge's anchorages are giant hunks of heavily reinforced concrete. Imagine a cube of super-reinforced concrete 12 stories to a side. That's the scale of what we're talking about.
You can absolutely forget about destroying one of the anchorages directly. They would be trivial to hit. They're giant hunks of concrete. But anything short of an atomic bomb would have trouble doing significant damage to them. While bunker-buster bombs exist, those are made to punch a hole through many feet of concrete and then explode in the air below the concrete. They're not designed to turn a massive 30 meter cube of solid concrete into gravel. It takes a minimum amount of energy to pulverize something that large. And that amount of explosives just can't be delivered by a plane or missile. And even if a bomb takes out a chunk of an anchorage, you've only managed to sever a few dozen of the thousands of wires holding up the bridge. Destroying the anchorages themselves would be even more impractical than destroying regular bridge piers.
So that leaves the cables themselves. You mentioned severing them at the anchorages, but it actually doesn't matter where they're severed. Imagine hanging a rope between two walls in the room you're in now. It doesn't matter where you cut that rope; anything hanging from that rope is going to fall. However, the best point to target would be right where the cables hang from the supporting towers. That is where the tensile forces in the cables are at their maximum.
I'm no expert in military ordnance. I have no doubt the Air Force has studied the problem extensively, but I really don't know how effective bombs are at taking out suspension bridge cables. I don't know exactly how precise the US Air Force is nowadays with their precision bombing, but I'll take it for a given that they have the ability to reliably get a direct hit on one a 1-meter wide bridge cable. Unlike in Vietnam, I'll assume we can actually hit the thing reliably.
You're talking about a cable that is made of thousands of individual wires. The Golden Gate Bridge's main cables are a meter thick. They look like this.
This isn't the type of target most military bombs are designed to destroy. Broadly speaking, there are two main types of bombs. There are area weapons and penetrators. The area bombs subject a large area of ground to heat, shock wave, and high speed debris. Some bombs are designed to say, kill every unarmored person and any lightly armored vehicle within a hundred meter radius. These area weapons would be completely useless on bridge cables. Even with a direct hit, most of the explosive force would bounce off the cable and into the air. You'll probably sever a few of the surface wires, but the vast majority of the cable's capacity will remain intact. And those things are built with a factor of safety. The Golden Gate Bridge was built with a factor of safety of about 2.5. Which means in theory you could cut through more than half of both of each main cable's cross-sectional area, at the point of maximum cable tension, and the thing would still stand.
That leaves the penetrators. Bunker buster bombs have already been mentioned. But what I'm thinking of are the shaped charge weapons designed to punch through things like tank armor. These weapons work by using an explosion to create a pencil-sized jet of superheated molten metal. This instantly drills a small hole through the armor of a tank. This is effective at destroying tanks, as that superheated stream of metal enters the tank cabin, rapidly expands, ricochets off the walls, and pastes everyone inside. And the resulting rapidly expanding gases can blow the turret right off some tanks.
But where my knowledge fails is how effective these shaped charges would be against a meter-thick bundle of steel wires. A shaped charge would certainly be capable of punching a hole, but if you want to sever the cable, you need to sever the entire cross section. A shaped charge may not have enough energy for that, or the stream of vaporized metal might just pass right through the cable, in one side and right out the other. I won't say it's impossible, especially if you designed a bomb specifically for targets like this. But whether a shaped charge that is designed to puncture tank armor can sever a big suspension bridge cable? I'm sure the Air Force knows, but that's beyond my expertise. I'm sure it's been thoroughly studied, and I'm sure those studies are classified to all hell and back. It's possible there may be information on this publicly available, but I feel dicey enough posting about severing suspension bridge cables on a public forum like this. Even if such info is publicly available, I would rather not have some angry men in black suits show up on my front porch asking why I've been reading numerous papers on how to effectively sever the cables of giant suspension bridges. I don't need that in my life right now. 😅
On the plus side, this actually makes big suspension bridges very resilient to terrorist attacks. A specialized shaped charge missile built by Lockheed Martin specifically to sever large suspension bridge cables could do the job. But you can't destroy the Golden Gate Bridge by setting off a home-made truck bomb on it a al Oklahoma City. You would blow a hole in the bridge deck, kill a lot of people, maybe sever some of the support cables, and maybe damage some of the outer layers of the main cables. But if you set of a truck bomb right next one of the main cables, again most of the explosive force would just bounce off. A meter thick steel element is pretty damn resilient. I'm not aware of any incidents of a major long-span suspension bridge being taken down by terrorist bombs like this.
Thank for taking the time to write such a through explanation.
I had some awareness that suspension bridge cables were actually bundles of cables, but had no idea just how many there as in it and how tick it is. Also I had no idea they were made with such a large safety factors.
I'm from Lisbon in Portugal were there is a bridge pretty much like the golden gate bridge (photos), designed by the same people, so I've always been curious about how it.
That said, my question was more coming from the side of "maybe that's the explanation for why that suspended span in that US bridge isn't repaired" rather than "how easy it is to bring it down with air power" (though I found the points you made on that angle very interesting) - I was thinking that if the thing has a tendency to fail as a whole, it would be more costly to repair if it did than a traditional bridge.
I have extensively worked in Demolition. Salvage, and Scrap. Breaking shit is only hard when you are using the wrong tool for the job.
And unfortunately for the US Air Force, planes and bombs are the wrong tool to take down a bridge.
I'm going to assume that with a simple jackhammer or a few small shaped charges, some time to work, and a lack of concern for your own life, you could "proper tool" a bridge to the ground pretty easily.
Exactly. Give me a couple days and a big enough angle grinder and I can take the Golden Gate Bridge down. (Assuming I have no regard for my own safety.) But the big steel cables holding the bridge up can be cut just like any other steel. Of course, I don't actually want to take down the Golden Gate Bridge. But even if I did, it wouldn't be having the right tools that would prevent me from doing it. It would be the fact that if I tried it, I would probably be beaten to death by a crowd of angry people before the police could even arrive. You show up with a giant cut off disk and start going to town on the cables supporting a bridge holding up thousands of cars? You probably won't even live long enough to see those terrorism charges.
That's the problem with taking bridges out from the air. You can't get up close and use the proper tools. You have bombs, missiles, and that's it.
Blowing up a car is way easier than blowing up a bridge.