^^Yes, the shape is obviously extremely important (just look up the basic drag law, the force is proportional to velocity, air density, viscosity, area, all sorts), but the point is that the air resistance makes a HUGE difference to the speed reached.
Let's just assume, for one second, that the train does reach 100mph at the bottom of the drop. In a vacuum, so with NO air resistance, lets look how fast the lift would have to be to reach the big 100mph.
Final Speed - v - 100mph (44.44m/s)
Acceleration - a - 9.81m/s^2
Distance - s - 305ft (92.964m)
Initial Speed - u - unknown
Using the constant acceleration formula:
(v^2)=(u^2)+2as
Then:
(u^2)=(v^2)-2as
So:
(u^2)=(44.44^2)-(2x9.81x92.964)
(u^2)=150.96
u=12.3m/s
So the lift has to move at 12.3m/s (27mph) to reach the 100mph speed. Don't forget this is in a vacuum, so with NO air resistance. I just somehow don't see how this will reach 100mph... I'm pretty sure you won't actually care about the sums, but at least they show that it's unlikely. Provided, of course, that I haven't ****ed something up on the way!