# What would happen if you cut the cables on the Golden Gate Bridge? **URL:** \ **Category:** Factual Questions\ **Created:** [August 14, 2012, 2:05am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428 "2012-08-14T02:05:16Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\ **Post date:** [August 14, 2012, 2:05am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/1 "2012-08-14T02:05:16Z")
Would it collapse? Are those vertical cables used to actually hold up the road portion or are they just for decoration? If they’re actually structural, does that mean those two horizontal cables actually hold up the entire bridge? That’s amazing… ---
**Author:** ![AndrewL](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@AndrewL](https://boards.straightdope.com/u/AndrewL)\ **Post date:** [August 14, 2012, 2:09am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/2 "2012-08-14T02:09:44Z")
Yes, the cables hold up the entire roadway. If you cut the cables anywhere along their length, the entire roadway will fall into the water. (This is something that movies nearly always get wrong). ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [August 14, 2012, 2:46am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/3 "2012-08-14T02:46:02Z")
> [@AndrewL](#): > > Yes, the cables hold up the entire roadway. If you cut the cables anywhere along their length, the entire roadway will fall into the water. (This is something that movies nearly always get wrong). Are you claiming that if one vertical cable were cut the entire roadway would collapse? Unless the cables are looped so there’s really only one (which I doubt), this sounds liek a sever under-design on the bridge. It’s been a long time since I studied engineering, but as I recall bridges are designed with safety factors over 2. Certainly one missing cable wold be more than adequately compensated for by its neighbors. ---
**Author:** ![Morgenstern](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@Morgenstern](https://boards.straightdope.com/u/Morgenstern)\ **Post date:** [August 14, 2012, 2:57am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/4 "2012-08-14T02:57:23Z")
> [@OldGuy](#): > > Are you claiming that if one vertical cable were cut the entire roadway would collapse? Unless the cables are looped so there’s really only one (which I doubt), this sounds liek a sever under-design on the bridge. It’s been a long time since I studied engineering, but as I recall bridges are designed with safety factors over 2. Certainly one missing cable wold be more than adequately compensated for by its neighbors. I think he was referring to the long, horizontal cables that run from shore to shore. Not the vertical ones that hang the roadway from the cables. ---
**Author:** ![The\_Second\_Stone](https://avatars.discourse-cdn.com/v4/letter/t/bbe5ce/32.png) [@The\_Second\_Stone](https://boards.straightdope.com/u/The_Second_Stone)\ **Post date:** [August 14, 2012, 3:15am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/5 "2012-08-14T03:15:43Z")
The east and west sides have horizontal cables that run from one end of the bridge to the other. They are not really horizontal, but curved. Two of them. They are about 3 feet in diameter. There are lots of vertical cables about 2 inches in diameter from the roadbed to the thick cables. The loss of a few vertical cables would not be catastrophic. The loss of either of the 3 foot cables would pull apart the whole bridge. ---
**Author:** ![Fubaya](https://avatars.discourse-cdn.com/v4/letter/f/c2a13f/32.png) [@Fubaya](https://boards.straightdope.com/u/Fubaya)\ **Post date:** [August 14, 2012, 3:51am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/6 "2012-08-14T03:51:58Z")
The two horizontal main cables hold up everything. What you see is actually a casing, [inside](http://usa.amateurtraveler.com/2012/01/05/golden-gate-bridge-cable-cross-section-san-francisco-california-daily-photo/) are 27,000 smaller cables. They were made by spinning cable from one end to the other, over and over again, for six months. The vertical cables which connect the road to the main cables are called suspender cables, and they more or less just connect the road to the main cables. You could probably cut a few of them and not collapse the roadway. They’ve all been replaced before, one at a time I’d imagine. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [August 14, 2012, 7:05am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/7 "2012-08-14T07:05:06Z")
> [@Fubaya](#): > > The two horizontal main cables hold up everything. What you see is actually a casing, [inside](http://usa.amateurtraveler.com/2012/01/05/golden-gate-bridge-cable-cross-section-san-francisco-california-daily-photo/) are 27,000 smaller cables. They were made by spinning cable from one end to the other, over and over again, for six months… Can you rephrase this? _One_ cable, like a humongous spider’s web thread? That can’t be, so I’m totally misunderstanding the technique. Great photo, BTW. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [August 14, 2012, 8:42am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/8 "2012-08-14T08:42:57Z")
> [@Leo\_Bloom](#): > > Can you rephrase this? _One_ cable, like a humongous spider’s web thread? That can’t be, so I’m totally misunderstanding the technique. > > Great photo, BTW. Think of a thick hemp rope – a thick rope made of thinner strands twisted around each other for the length of the rope. The huge thick catenary cables (the curved ones) actually consist of a bundle of thinner cables. (And I’m not sure any more, if the thinner cables each consist of a bundle of even thinner wires, or if they are solid.) At the south end of the bridge (the San Francisco end) is a small park and visitor center. There is a section of the cable on public display there. ETA: [Link to some pictures](http://media.photobucket.com/image/golden%20gate%20bridge%20cable/rodrounds/12-06-08%20Ride/P1030164.jpg) ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [August 14, 2012, 9:22am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/9 "2012-08-14T09:22:35Z")
> [@Reply](#): > > Are those vertical cables used to actually hold up the road portion or are they just for decoration? > > If they’re actually structural, does that mean those two horizontal cables actually hold up the entire bridge? That’s amazing… If just decoration, it was mighty expensive decoration as a significant portion of the world’s steel production those years went for just those cables! The horizontal cables are anchored at each end in concrete boxes, whose dimensions are also amazing. I watched a TV documentary (History Channel?) about the bridge with several interesting topics. I’d guess there are excerpts on Youtube, but the first to turn up for me is [an old 26-minute Bethlehem Steel film](http://www.youtube.com/watch?v=FKU1PTyHtbM) which, I’ll guess, contains some of the same footage as the documentary I watched. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [August 14, 2012, 11:12am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/10 "2012-08-14T11:12:47Z")
> [@Reply](#): > > Would it collapse? Are those vertical cables used to actually hold up the road portion or are they just for decoration? > > If they’re actually structural, does that mean those two horizontal cables actually hold up the entire bridge? That’s amazing… How else would the bridge be held up? The roadway is certainly not rigid enough to be cantilevered out from the bridge supports. [Suspension bridges](http://en.wikipedia.org/wiki/Suspension_bridge) are a rather elegant and efficient design, taking advantage of the high tensile strength of steel cables. The weight of the bridge is ultimately held by the anchors where the cables are attached at either end. (In many bridges these go directly into the bedrock, but the Golden Gate bridge has massive [concrete anchor towers](http://mw2.google.com/mw-panoramio/photos/medium/63085755.jpg).) ---
**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\ **Post date:** [August 14, 2012, 8:48pm UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/11 "2012-08-14T20:48:30Z")
I guess I just never really thought about it. Like skyscrapers, bridges are just one of those feats of engineering that I’ve taken for granted, but when I really pause and consider how they were built… nothing short of astonishing. I’ll probably check out one of those documentaries 🙂 ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [August 14, 2012, 8:52pm UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/12 "2012-08-14T20:52:11Z")
If you cut all the vertical cables, the horizontal cables would change from a (mostly) parabolic shape to a (mostly) catenary shape. And of course, the roadway would fall and drown the motorists, but that’s of little consequence compared to the mathmatics! ---
**Author:** ![chacoguy](https://avatars.discourse-cdn.com/v4/letter/c/50afbb/32.png) [@chacoguy](https://boards.straightdope.com/u/chacoguy)\ **Post date:** [August 14, 2012, 11:58pm UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/13 "2012-08-14T23:58:05Z")
You would be arrested for terrorism. ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [August 15, 2012, 12:08am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/14 "2012-08-15T00:08:30Z")
> [@chacoguy](#): > > You would be arrested for terrorism. But how would they get to you? ---
**Author:** ![Mdcastle](https://avatars.discourse-cdn.com/v4/letter/m/958977/32.png) [@Mdcastle](https://boards.straightdope.com/u/Mdcastle)\ **Post date:** [August 15, 2012, 12:49am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/15 "2012-08-15T00:49:38Z")
It has happened that a horizontal cable (or rather in this case an eyebar rather than a cable) failed. The Silver Bridge wound up in the Ohio River along with 46 people in 1967. ---
**Author:** ![Fubaya](https://avatars.discourse-cdn.com/v4/letter/f/c2a13f/32.png) [@Fubaya](https://boards.straightdope.com/u/Fubaya)\ **Post date:** [August 15, 2012, 3:45am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/16 "2012-08-15T03:45:44Z")
> [@Leo\_Bloom](#): > > Can you rephrase this? _One_ cable, like a humongous spider’s web thread? That can’t be, so I’m totally misunderstanding the technique. > > Great photo, BTW. I’m not sure what you’re asking. Are you asking whether they spun one cable back and forth 27,000 times? I should have worded is differently, I think it was 27,000 different cables. Then they took a machine that wrapped itself around the cables and squeezed, compacting them really tight and forming them into a near perfect circle. Then then they put a casing around it, which you can see in the [photo](http://usa.amateurtraveler.com/2012/01/05/golden-gate-bridge-cable-cross-section-san-francisco-california-daily-photo/) I posted earlier. ---
**Author:** ![zombywoof](https://avatars.discourse-cdn.com/v4/letter/z/9e8a1a/32.png) [@zombywoof](https://boards.straightdope.com/u/zombywoof)\ **Post date:** [August 15, 2012, 3:59am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/17 "2012-08-15T03:59:41Z")
For anyone REALLY interested in this stuff I recommend [this book](http://www.amazon.com/The-Great-Bridge-Building-Brooklyn/dp/067145711X) about the construction of the Brooklyn Bridge - which goes into great detail about not only the way the cables were laid but the (perhaps even more technically interesting) underwater construction of the tower bases - as well as the dramatic personal stories of the family the family that designed and built the bridge, the politics of the time and the questionable wheeling and dealing involved in the planning and financing, etc. ---
**Author:** ![Koxinga](https://avatars.discourse-cdn.com/v4/letter/k/4af34b/32.png) [@Koxinga](https://boards.straightdope.com/u/Koxinga)\ **Post date:** [August 15, 2012, 4:05am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/18 "2012-08-15T04:05:50Z")
> [@Mdcastleman](#): > > It has happened that a horizontal cable (or rather in this case an eyebar rather than a cable) failed. The Silver Bridge wound up in the Ohio River along with 46 people in 1967. That was all down the Mothman, though, wasn’t it? ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [August 15, 2012, 5:58am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/19 "2012-08-15T05:58:39Z")
> [@Leo\_Bloom](#): > > _One_ cable, like a humongous spider’s web thread? That can’t be, so I’m totally misunderstanding the technique. Here’s the Bethlehem video, [fast-forwarded to the cable spinning](http://www.youtube.com/watch?v=FKU1PTyHtbM#t=895). (The History Channel documentary is much more interesting than the Bethlehem video, IMO.) ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [August 15, 2012, 8:39am UTC](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428/20 "2012-08-15T08:39:57Z")
> [@Colophon](#): > > How else would the bridge be held up? The roadway is certainly not rigid enough to be cantilevered out from the bridge supports. [Suspension bridges](http://en.wikipedia.org/wiki/Suspension_bridge) are a rather elegant and efficient design, taking advantage of the high tensile strength of steel cables. I think it was on an episode of _Dirty Jobs_ where Mike was painting the Mackinac Bridge that he showed that the roadway is not even connected to the towers. The towers hold up the main cables, the main cables hold up the suspender cables, the suspender cables hold up the road. It’s not all just for looks. > [@](#): > > The weight of the bridge is ultimately held by the anchors where the cables are attached at either end. (In many bridges these go directly into the bedrock, but the Golden Gate bridge has massive [concrete anchor towers](http://mw2.google.com/mw-panoramio/photos/medium/63085755.jpg).) I did a web search for a good diagram of the cable anchorage and found [this one](http://www.brantacan.co.uk/AnchorageA2.gif) that shows how the strands of cable spread out so they can withstand the tension. Where did I find that link? [straightdope.com](http://straightdope.com), in [this thread](http://boards.straightdope.com/sdmb/showthread.php?t=580313) about whether the Brooklyn Bridge could collapse if one of the cables failed. [Next page](https://boards.straightdope.com/t/what-would-happen-if-you-cut-the-cables-on-the-golden-gate-bridge/631428.md?page=2)