Are there either cars or buses?
Yes, there is a bus.
     src        edge_attr  dst
0      0  to the right of    8
1      0  to the right of   22
2      0  to the right of   19
3      0  to the right of   15
4      0  to the right of   12
..   ...              ...  ...
503   47   to the left of    7
504   47   to the left of    2
505   47   to the left of   45
506   47   to the left of   17
507   47   to the left of   20

[508 rows x 3 columns]