What is the train on?
The train is on the train tracks.
    src        edge_attr  dst
0     0   to the left of    3
1     2   to the left of    7
2     3  to the right of    0
3     6   to the left of    9
4     6   to the left of   11
5     7               on    5
6     7  to the right of    2
7     7               in    4
8     8   to the left of   11
9     9   to the left of   11
10    9  to the right of    6
11   10  to the right of   12
12   11  to the right of    9
13   11  to the right of    6
14   11  to the right of    8
15   12   to the left of   10