CTA Bell

At CTA stations, the end of the track should be terminated with a pressure plate to trigger note blocks. Here's how you do it:

Step 1: Prepare tracks

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Starting tracks
Break 2 sections of track. Place a stone pressure plate on the first empty block, and another block (any type) on the second empty block.
Directly underneath the block containing the stone pressure plate, place redstone dust (for both tracks). This marks where your pressure plate is once you dig the room under the tracks.

Step 2: Dig bell room

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Dig down 3 blocks, so the roof is the same level as the tracks. The block containing the redstone should be 2 blocks above the floor of the room.
Dig out a room that contains both of the redstone "towers", and make it large enough (at least 10x20 blocks)

Step 3: Lay redstone

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Connect the two pieces of redstone into a single wire.
Create a fork partway through the wire, and fork it out to two pieces of wool. The wool is important, as it will make a bell noise. The redstone must be directed at the wool, otherwise, the bell will not work.
Do the same on the other side, except make the wool at least 5 blocks away from the wire. A delay circuit will go here, and it needs a little bit more room.
Place 2 blocks halfway in the wire you just made. Ideally, to get the most delay, the two blocks should be facing north-south.
Place redstone torches as shown.
Place redstone wire on the last block.
Place a block on top of the redstone torch as shown.

Step 4: Note blocks

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Place note blocks on each of the 4 wool blocks.
Tune the two note blocks not connected to the delay circuit to A (15 clicks) and E (10 clicks) as shown.
Tune the two note blocks connected to the delay circuit to F# (12 clicks) and C# (7 clicks) as shown.