What vehicle is on top of the bridge?
The vehicle is a bus.
    src        edge_attr  dst
0     0  to the right of   14
1     1               on   12
2     1   to the left of    8
3     1   to the left of   14
4     2  to the right of   13
5     2               in   15
6     2  to the right of    6
7     3            above   10
8     4        on top of   13
9     5               in   10
10    5               on   10
11    6   to the left of    2
12    6        on top of    9
13    6   to the left of   13
14    7        on top of    0
15    8        on top of    3
16    8               on    3
17    8  to the right of    1
18    9   to the left of   13
19   10               by    0
20   13  to the right of    9
21   13  to the right of    6
22   13   to the left of    2
23   14   to the left of    0
24   14  to the right of    1