What is the color of the bridge the train is on?
The bridge is blue.
    src        edge_attr  dst
0     0   to the left of    6
1     1               on    4
2     1            above    6
3     1  to the right of    5
4     2   to the left of   10
5     5   to the left of    1
6     6            below    1
7     6  to the right of    0
8     7  to the right of    9
9     7   to the left of   11
10    9   to the left of    7
11   10  to the right of    2
12   11               in    1
13   11  to the right of    7