What is beneath the tracks?
The gravel is beneath the tracks.
   src        edge_attr  dst
0    0   on the side of    2
1    2      in front of    8
2    2               on    3
3    3            above    7
4    6  to the right of    9
5    7          beneath    3
6    8           behind    2
7    9   to the left of    6
8   10  to the right of   11
9   11   to the left of   10