What happens after a collision at a crossing?
A long investigation involving the railroad, the signals, the sightlines and possibly a public authority. Fault is genuinely complicated and slow. None of that pays a medical bill in the meantime, which is why your own medical payments and health cover carry the first period.
Are my state minimum limits enough?
Not remotely, for this kind of injury. Minimum limits were never designed for catastrophic harm. Raising them is inexpensive relative to the exposure, and underinsured motorist cover is the piece that protects you rather than other people.
What should I carry specifically?
Medical payments at a meaningful figure, underinsured motorist matched to your liability, and collision so the vehicle is dealt with immediately. Those three are the ones you control and the ones that function while everything else is argued about.