I'm going to shamelessly necro this thread, firstly because it's a treasure trove of info not very well documented elsewhere, and also because I have something to report myself.
It
has been noted before that track ramps with only one upwards exit behave a bit oddly, not imparting deceleration on carts using them to travel upwards. This has been interpreted as the cart treating the ramp as essentially flat track, but I have good reasons to believe that's not quite or at least not entirely true, and that the minecart is in fact sent very slightly
airborne.
To demonstrate this, here's a quick experiment - send a cart up a ramp that's only connected to the upper z-level at below derail speed, then tweak your setup and observe again.
- Place a corner shortly behind the ramp; two tiles behind should be ideal. The minecart will ignore this corner and fly off the track.
- Put a wall tile behind the corner, in a way that would stop the derail. The cart will now stop completely on the corner tile.
- Replace the corner with a ramp (can be impulse). The cart will start flashing after a while (presumably indicating a landing) and react to the ramp with a delay. (at least that's how it looks in ASCII)
This was tested on an older version, but I don't think minecart physics had been updated much since. Also, it seems true such ramps produce no downward acceleration the other way at least.