What kind of vehicle is sitting on the train tracks?
The vehicle is a train.
    src        edge_attr  dst
0     1               at   11
1     1   to the left of   12
2     2  to the right of    9
3     2           behind   12
4     5           beside   12
5     6          beneath   12
6     6            below   12
7     9   to the left of    2
8    12       sitting on    6
9    12  to the right of    1
10   12               on    6
11   12            above    6
12   12      in front of    2