What is the name of the vehicle that drives on the road that looks gray?
The vehicle is a truck.
    src         edge_attr  dst
0     0  parked alongside   11
1     0    to the left of    3
2     0    to the left of    7
3     0         parked on   11
4     0        driving on   11
5     1    to the left of    5
6     1    to the left of   13
7     1    to the left of    8
8     1    to the left of    9
9     1    to the left of    4
10    2    on the side of   11
11    3   to the right of    0
12    3   to the right of   13
13    3   to the right of    8
14    4   to the right of   13
15    4   to the right of    9
16    4   on the front of    0
17    4   to the right of    1
18    4                of    0
19    4   to the right of    5
20    5    to the left of   12
21    5   to the right of    1
22    5    on the side of    0
23    5    to the left of    4
24    6    to the left of   10
25    7   to the right of   13
26    7   to the right of   12
27    7    on the side of   11
28    7   to the right of    0
29    7   to the right of    9
30    7   to the right of    8
31    8                of    0
32    8    to the left of    7
33    8   to the right of    1
34    8    to the left of    3
35    9       standing in    0
36    9   to the right of    1
37    9       standing in    8
38    9    to the left of    7
39    9    to the left of    4
40    9    to the left of   12
41   10                of    0
42   10   to the right of    6
43   12   to the right of   13
44   12    to the left of    7
45   12   to the right of    9
46   12   to the right of    5
47   12          stuck on    4
48   13                of    0
49   13    to the left of    4
50   13    to the left of    3
51   13   to the right of    1
52   13    to the left of   12
53   13    to the left of    7