During a recent trip on an Amtrak train, I boarded the train (which was train 506), sat in my seat (which was in car 8), and waited for departure. As I sat in my seat, I noticed one man come into my car, only to realize he was in car 8 instead of car 7. Shortly there after, a couple boarded my car. The man and the woman were discussing which way they should go to find their seats. The man said, "Here are our seats: 19 and 20." The woman responded, "I don't think these are ours, I think our car is down one." All three of these people had entered the wrong car. They meant to enter car 7, but instead entered car 8. Why was this happening?

The reason has to do with the electronic panels that display the train number and the car number. They are displayed on your right as you enter the train, but the number on the panel refers to the car that is to your left.

Figure 2: After stepping onto the train, the car number on the electronic panel is to your left.

Imagine that we are assigned to car 8. Figure 1 shows the view from the outside of the train where the electronic panel to our right tells us that this train is 506 and this car is 008. If we step up onto the train (as in Figure 2), there is a small number on the wall showing us that the car to our right is car 9. The actual car we want (car 8) is to our left. If we had not seen that small sign, we would likely think that car 8 is to the right. This would be logical since the panel was to our right as we entered (see Figure 3).

The Design Tradeoff
So, why was this confusing design chosen? The sliding door is the root of all the problems.

The doorway resides on one end of the car. The sliding door must slide toward the middle of the car because if it slid the other way, it would cover the connection between its car and the next, making it impossible for the door to open on a curvy track. If the electronic panel was on the other side, then it would not be visible when the door is open.

Design Alternatives
There are many potential solutions. A simple and inexpensive solution would be to place an arrow next to or on the panel indicating the direction of the car in question.

Or the doorway could be positioned so that it is just far enough away from the end of the car to open the door in that direction, placing the electronic panel on the other side. This would increase the length of the hallway between cars and would decrease the seating area, perhaps decreasing the number of seats available.

The door could slide into to wall of the car instead of outside the wall, and a thin electronic panel could be placed on the appropriate side of the door (so that both door and panel are on the same side).

Finally, if there is room, the panel could appear above the door.