Do you see both a train and a bridge?
No, there is a bridge but no trains.
   src        edge_attr  dst
0    2  to the right of    6
1    4               on    7
2    4   to the left of   10
3    5               on    7
4    6            below    7
5    6   to the left of    2
6    7            above    6
7   10  to the right of    4