Do the barrier and the sign have a different colors?
Yes, the barrier is red and the sign is green.
    src        edge_attr  dst
0     0  to the right of   15
1     0  to the right of   18
2     0  to the right of   13
3     0   to the left of   11
4     0   to the left of    9
..  ...              ...  ...
71   19  to the right of   20
72   20   to the left of   19
73   20   to the left of    1
74   20   to the left of   17
75   20   to the left of    4

[76 rows x 3 columns]