What is the train on?
The train is on the bridge.
     src        edge_attr  dst
0      0   to the left of    5
1      0   to the left of    4
2      0               on   18
3      0        on top of   18
4      0   to the left of   24
..   ...              ...  ...
132   27   to the left of   24
133   27  to the right of   15
134   28  to the right of   24
135   28  to the right of    4
136   28  to the right of    5

[137 rows x 3 columns]