Why are train tracks flat?

I’m not so sure. Modern trains are the result of a lot of development and there’s a huge manufacture base to support them, which gives an unfair advantage over any completely new technology, but there are a lot of specially developed solutions out there where a lot of money has been thrown at the problem of moving people and/or goods efficiently and they haven’t really resulted in anything that can rival the basic concept of trains.

In what way?

New rail lines are still being built. And many of them are independent systems (light rail and subways) that don’t connect to an existing network, so compatibility isn’t an issue. Which shows that we haven’t invented anything that’s different and better.

Of course, there are new systems that work better in some situations. Monorails can be cheaper to build through densely populated cities. Automated guideway transit systems work well for small people-mover systems, like those at airports. But there seems to be nothing that can beat the efficiency and capacity of a conventional railway. (The linear motor propelled trains seem to work well for subways and light rail, but that’s still a railway, albeit with a new propulsion method.)

Huh, I had always thought “rolling resistance” meant friction in the wheel bearing and/or the drive train, but it seems that (a) the resistance due to deformations of the wheels is usually included in this as well, and (b) some sources take “rolling resistance” to mean only the resistive forces due to deformations of the wheels. Ignorance fought.

Here’s a list of the steepest gradients on adhesion railways: https://en.wikipedia.org/wiki/List_of_steepest_gradients_on_adhesion_railways

Thanks a lot for the link. Now I know what I’ll be doing for the next few days! :slight_smile:

I watched the video about how mirrors work and I realized how simple the explanation really is. Well worth the time spent.

For one, the tracks might be wider (speed on curves). Or worldwide, the width of all tracks would be the same.

Speed is not the only consideration. Track gauge is a trade-off between speed, construction cost, availability of space, curve radius, carrying capacity, and other factors. Even after the “standard gauge” (4’8.5") became a widespread standard, many regions chose non-standard gauges to fit specific needs. Such as the entire country of Japan, which chose a narrower gauge better suited for the mountainous terrain. Logging railroads in the US used narrow gauge for the same reason. Russia has a lot of wide-open expanses, so the 5ft gauge became standard. Australia uses an even wider 5’3" gauge in some long-distance routes.

Here’s Snoop’s debunking of the urban legend that current standard railroad gauge is based on the width of Roman chariots. I heard the legend in the form that this width actually came from prehistory, the Romans fit their chariots to the existing roads.

The connection to the Space Shuttle is a new one to me … the size of the SRB is based on the width of a horse’s ass … go on …

Rolling trains are so efficient that one company plans on using them to store excess wind energy. Move heavy things up a track to store the energy, down to release it.

Contrast with using a dam and pumping water back up to the reservoir during surplus times.

I was about to correct you, because I assumed you were referring to the famous Budapest Castle Funicular, which is not a cog railway. I am familiar with it because I rode it on a visit back in 2010.

But I decided to check out Wikipedia’s list of cog railways, and you are right: there is a true cog railway in Budapest, Tram line number 60, that I didn’t know about. Now I’m peeved I didn’t ride it when I was there.

I’ve ridden on one cog railway, the Snowdon Mountain Railway in Wales. Beautiful ride, with a 1 in 5 climb at its steepest point. I’ve also ridden on the Cass Scenic Railway, number 3 on Anaglyph’s list of steepest adhesion railways.

The rail storage technique is actually pretty close to pumped hydro in terms of efficiency. But the rail system has the advantage that you don’t need a river nearby. And building it is significantly less disruptive than building a dam.

And 5’ 6" for Bay Area Rapid Transit (for some incomprehensible reason, and which is now biting them in the ass).

Yeah, it’s an excellent series. I also recommend the one on how magnets work (spoiler: you don’t actually find out how magnets work).

But you do realize that you never actually knew, either.

Synchronicity: just two days ago I saw a weird-looking train parked in Livingston Montana. Over the din I asked a guy climbing around it what it was. “RAIL GRINDER! ROUNDS OFF THE RAILS!” he shouted. “EIGHTY-EIGHT OF THESE RUNNING ALL THE TIME!” He pointed to the round things under the handrails here.

Also, when it fails, you only release (at most) a single train’s worth of energy instead of an entire lake’s worth.

Quite comprehensible. To help resist crosswinds on the Golden Gate Bridge. The gauge was chosen before Marin decided not to be part of the BART District.

The story I’d heard is something-something passenger comfort. The crosswind story is no more believable; although the GG can have high winds, they aren’t ridiculously high, and other places do just fine on standard gauge. And anyway, they can close the crossing if winds get too crazy (which they already do for passenger vehicles). Worst-case, put up some static wind barriers.

You’re essentially saying that they gave up gauge compatibility (which was obviously a stupid choice even then, and has become only more obviously stupid given the recent component supply problems) to solve a worst-case environmental condition that had several alternative solutions, and which ended up not being an issue anyway.

Worst idea since putting wings on the Shuttle. Though maybe not a surprise since BART was also developed by an aerospace company.

And has significantly less capacity.