Are the railroad tracks dark brown?
Yes, the railroad tracks are dark brown.
    src        edge_attr  dst
0     1   to the left of    6
1     1             near    7
2     2               in    3
3     4   to the left of    9
4     4   to the left of    6
5     4  to the right of    5
6     5   to the left of    4
7     6  to the right of    1
8     6  to the right of    4
9     6  to the right of    7
10    7          next to    1
11    7               by    1
12    7   to the left of    6
13    7   to the left of    9
14    9  to the right of    4
15    9  to the right of    7
16   10  to the right of   11
17   11   to the left of   10