What is the vehicle that the passengers are on?
The vehicle is a train.
    src        edge_attr  dst
0     0      in front of   17
1     0      in front of   19
2     0   to the left of   10
3     0  to the right of   11
4     0  to the right of   16
..  ...              ...  ...
65   18  to the right of   11
66   18  to the right of    5
67   18               on    6
68   19           around    0
69   19           behind    0

[70 rows x 3 columns]