What is the bridge made of?
The bridge is made of metal.
    src        edge_attr  dst
0     0             near   16
1     1  to the right of    7
2     2   to the left of    5
3     3  to the right of    4
4     3      standing on   12
5     4   to the left of    3
6     4      floating in   15
7     5  to the right of   13
8     5  to the right of    2
9     5      floating in   15
10    5  to the right of   12
11    6  to the right of   16
12    6  to the right of    9
13    7   to the left of   10
14    7   to the left of   11
15    7   to the left of    1
16    7   to the left of    9
17    8   to the left of   17
18    9  to the right of    7
19    9   to the left of    6
20   10   to the left of   11
21   10   to the left of   16
22   10  to the right of    7
23   11  to the right of   10
24   11  to the right of    7
25   11   to the left of   16
26   12   to the left of    5
27   13   to the left of    5
28   16  to the right of   10
29   16   to the left of    6
30   16          next to    0
31   16  to the right of   11
32   17  to the right of    8