Are there either any buses or trains that are not black?
No, there is a train but it is black.
    src        edge_attr  dst
0     0   to the left of   21
1     0   to the left of   16
2     1  to the right of   12
3     1  to the right of    9
4     2   to the left of   23
..  ...              ...  ...
92   23  to the right of    2
93   23  to the right of   13
94   23   to the left of   20
95   24   to the left of   21
96   24  to the right of   14

[97 rows x 3 columns]