And the Coaster was planned to exceed 200 MPH, and dip underwater!
Could you even survive roller coaster turns & dips, at 200 mph?
“The car would also briefly be submerged under water in the San Francisco Bay.” (from the article, for the proposed coaster on the Bay Bridge)
That’s nuts!
That’s a wild idea. As for 200 mph, there’d have to be a windscreen, or the cars would have to be enclosed.
I don’t think there’s ever been a roller coaster on a highly-trafficked bridge. Although in Japan the Eshima Ohashi Bridge is nicknamed the “roller coaster bridge” because it is quite steep (images here).
As noted, speed only matters as to wind blast. Given a cabin, speed becomes immaterial. But you are onto something else …
Short version is you don’t make very sharp turns at 200mph. So a faster coaster would need to be proportionally larger to maintain fun rather than miserable, or even fatal, levels of acceleration
Longer version is the relevant equation is
centripetal acceleration = speed^2 / turn radius.
Which in English says that when you are going fast, you either pull big Gs turning or have a big turn radius or some of each. Those last two factors trade off directly.
200mph is roughly 300 feet per second. And WAG 3G is about all that an untrained customer would find fun if sustained for more than a couple seconds. 1G = 32 ft/sec/sec, so 3G ~= 100 ft/sec/sec. So rearranging our equation and assuming a 3G turn at the max speed we’d get:
turn radius = speed ^2 / centripetal acceleration
turn radius = ~300^2 / ~100 = ~90,000 / ~100 = ~900 ft. radius. That’s big. If you made a Ferris wheel of the same radius, it’d stand 1800 feet tall, so ~ 3/8 mile. Roughly as tall as the replacement One World Trade Center building in NYC. Big. Really really big.
Well, the main span of the GGB would be appropriate for such a radius. It’s a catenary, not a segment of a circle, but just eyeballing it, I’d guess it’s close to a circle with a radius of about 4500 feet. I’d be more concerned about the vehicle applying forces on the cables in directions that the they were not designed to handle.
Before the coaster got built somebody would do those calcs. Whether in 2025 as a retrofit, or in 1930ish as part of the initial construction.
Looking at those blueprints, the dude was seriously optimistic about how much energy would be lost to air resistance and other frictional effects. There’s barely any height difference at all between those hills.