This detector block will detect any Minecart that passes adjacent to them. They can be placed under or beside rails. They will only provide power in the direction of the light. If you are using it for the turnpike in the picture, FACE it toward the Switch Motor. Or else, it will trigger the track.
Detector - Storage
Triggers only on Chest Carts.
Detector - Player
Triggers only if cart has a player in it.
Detector - Empty
Triggers on detecting an empty cart.
Detector - Mob
Triggers only on a cart with a monster in them.
Detector - Animal
Detector - Growth
Triggers only with an adult animal in them, does not trigger with a baby animal.
Detector - Explosive
Triggers only if a TNT cart passes.
Detector - Advanced
Uses a GUI to select which carts it triggers.
Detector - Tank
Triggers only on Tank Carts.
Detector - Energy
Detector - Powered
Detector - Train
Detector - Sheep
Only activates when a Sheep that is in a cart passes.