What vehicle is the ground in front of, a truck or a train?
The ground is in front of a truck.
    src        edge_attr  dst
0     2  to the right of    3
1     2               on   19
2     3   to the left of   12
3     3   to the left of   14
4     3   to the left of    2
5     3   to the left of   19
6     3   to the left of    5
7     4             near   16
8     4  to the right of   12
9     5   to the left of   18
10    5  to the right of    3
11    6   to the left of   12
12    6               on   11
13    7               on   16
14    7   to the left of   12
15    8  to the right of   14
16    8   to the left of   18
17   10      in front of   18
18   11      in front of   18
19   11      in front of   15
20   12   to the left of   16
21   12   to the left of   13
22   12          holding   13
23   12  to the right of    3
24   12   to the left of   18
25   12   to the left of    4
26   12  to the right of    6
27   12  to the right of    7
28   13  to the right of   17
29   13  to the right of   12
30   14  to the right of    3
31   14   to the left of    8
32   14   to the left of   18
33   16  to the right of   12
34   16             near    4
35   17   to the left of   13
36   18           behind   10
37   18  to the right of   12
38   18  to the right of   14
39   18  to the right of    8
40   18  to the right of    5
41   19  to the right of    3