Chinese engineer Song Youzhou has been trying to get traction for his straddling bus, a huge elevated bus that goes over, rather than through, traffic, since 2010.
Most recently, he presented it at the 2016 19th China Beijing International High-Tech Expo. The videos look amazing and exciting and promise a way for public transit to comprehensively beat private vehicles (albeit only ones with low clearance!).
But as Core 77's Rain Noe points out, the bus poses an intractable problem: its turning radius (early videos faked this by making the bus bend when it cornered). Without avenues as wide as Beijing's biggest boulevards, you'd have to make some serious materials and mechanical breakthrough to get it around even modest corners on most cities' widest streets.
In those shots, you can clearly see he's got the vehicle bending, as if it's made of rubber rather than steel.
This physics problem means that the vehicle either needs to be articulated every few feet along its length, or have articulating points with an extreme differential where the carriages meet. That will be tricky to execute given the vehicle's width–at seven meters it is nearly three times as wide as your average 2.5-meter-wide articulating bus–but not impossible to accomplish. Indeed, at the Beijing International High-Tech Expo, where Song presented a working scale model earlier this month, he has opted for the latter approach:
The Glaring Flaw in That "Land Airbus" Concept Everyone's Talking About
[Rain Noe/Core 77]
These Futuristic Elevated Buses Can't Arrive Soon Enough [Sarah Emerson/Motherboard]