Even if you insist on going through the cities in the valley they chose a construction sequence that takes the longest time to show any process. If they fast tracked LA-Bakersfield they could have extended the Amtrak San Joaquin service to LA by now. Concentrat on the SF-Merced section next and then you can work on the Merced-Bakersfield piece meal.
I thought they were unclear if LA-Bakerfield is even possible.
My understanding comes from a podcast that wasn't about the rail at all, it was about how to make decisions. In the podcast they gave the example that if you decide to have a music box and a dancing monkey at a fair to make money, which do you do first, make the music box or train the monkey. The answer is, train the monkey, because if you can't train the monkey there is no point in making the music box (something you know can be made).
Her point was people delude themselves into thinking they're making progress on a project by starting with the easy stuff. But the easy stuff is pointless if the hard stuff is impossible.
She gave the example of the California high-speed rail. They're building the flat easy part first but engineers have not figured out how they're going to build the train between Bakersfield and Los Angeles through the Tehachapi Mountains. Until they've figured that out the flat part is a waste of time and a false example of progress.
Depending on the depth of the tunnel and the construction of the structure, you can get vibrations through the ground and foundations of the structure transmitted such that they are noticeable.
e.g. If you live above a tube line in London (London Underground) then you may hear/feel rumbling every time a train passes under you.
which is used at 300kph by electric multiple units like the german Inter City Expres.
I've rode over this at about 330kph shortly after opening, it's slightly noticable, but not like a roller-coaster at all, as one might think.
Meanwhile this is also used by more conventional electrical engines for passenger trains up to 250kph, also in 'pusher' mode,
and short freight trains, no longer than 700m, at anything between 160 to 200kph during nights.
According to Wikipedia 'the Bakersfield–Palmdale section of the line will cross Tehachapi Pass, roughly parallelling the Union Pacific Railroad's Mojave Subdivision. Due to its heavy freight traffic and sharp curves (including the famous Tehachapi Loop), there is no current passenger service through the pass. While the proposed high-speed rail alignment will not include any long tunnels comparable to those in Pacheco Pass, it has nine shorter tunnels and several viaducts more than 200 feet (61 m) high. The maximum grade through the pass would be - 2.8 - percent, making it the steepest portion of the Phase 1 route.'
Okay, but the I-5 doesn't bother with loops and tunnels. It just barrels right over the top of the mountains, including a 5-mile section of 6% grade according to the sign (https://www.crashforensics.com/tejonpass.cfm). Trucks struggle to crawl over the top at like 30 mph, with tires. It's not exactly a roller coaster hill to be overcome with inertia.
They have distributed traction, meaning powered bogies in every second wagon for the current variants. There is no 'engine/locomotive' in the classical sense. All of these also have electronic anti-slip/traction control.
Edit: Even if a quarter of the powered bogies are defect for whichever reason, the remaining ones still suffice to accelerate from full stop at 4% grade. By design. For current variants. It's a variable platform. They could use more powered bogies. Stronger motors. Whatever.
