What is the road made of?
The road is made of concrete.
    src        edge_attr  dst
0     0  to the right of   10
1     0   to the left of    2
2     0  to the right of   14
3     0  to the right of   13
4     1   to the left of    9
5     2  to the right of    0
6     2               of    1
7     2  to the right of   10
8     2  to the right of    5
9     2  to the right of   14
10    2  to the right of   13
11    5   to the left of    2
12    5  to the right of   12
13    5  to the right of   10
14    5  to the right of   14
15    5  to the right of   13
16    6               on    9
17    8  to the right of   12
18    9  to the right of    1
19   10  to the right of   12
20   10   to the left of   13
21   10   to the left of   14
22   10   to the left of    0
23   10   to the left of    2
24   10   to the left of    5
25   11           beside    1
26   12   to the left of    8
27   12   to the left of    5
28   12   to the left of   14
29   12   to the left of   13
30   12   to the left of   10
31   13   to the left of    5
32   13   to the left of    2
33   13   to the left of    0
34   13  to the right of   10
35   13  to the right of   12
36   14   to the left of    0
37   14   to the left of    2
38   14  to the right of   10
39   14  to the right of   12
40   14   to the left of    5