Development of a Speeding-Related Crash Typology
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RESULTS FOR SINGLE-VARIABLE ANALYSES
The following sections describe the results of the single–variable analyses for the set of variables selected in the GES, FARS, North Carolina, and Ohio databases. For each variable, tables containing data from these four databases (and two definitions for the State data) are presented first, followed by a brief description of findings. It is noted that even though GES and FARS data are presented in the same table (with the State data in separate tables), the percentages of SR crashes within a given category should not be compared across databases. For example, FARS category percentages are likely to be higher than the same GES category percentages since, in general, the FARS data have a higher percentage of SR crashes (30 percent versus 20 percent).
Type of Collision
First Harmful Event
Nonmotorist Involvement
TYPES OF CRASHES MOST LIKELY DUE TO SPEEDING
In this section, tables are presented to examine the types of crashes that are most likely a result of speeding as well as the basic nature of SR crashes. The tables show the percentage of SR crashes by type of collision, first harmful event, and nonmotorist involvement.
Type of Collision
Table 7. Frequency and number/percentage of SR crashes regarding type of collision.
Type of Collision |
FARS |
GES |
All Crashes |
SR Crashes |
All Crashes |
SR Crashes |
n |
n |
Percent |
n |
n |
Percent |
Collision with motor vehicle |
Rear–end |
2,253 |
927 |
41.15 |
1,730,195 |
603,805 |
34.90 |
Head–on |
3,959 |
655 |
16.54 |
116,689 |
13,456 |
11.53 |
Angle |
|
|
|
1,681,286 |
97,530 |
|
Front–to–side, same direction |
484 |
131 |
27.07 |
|
|
|
Front–to–side, opposite direction |
2,243 |
611 |
27.24 |
|
|
|
Front–to–side, right angle |
5,024 |
828 |
16.48 |
|
|
|
Front–to–side, unknown direction |
289 |
33 |
11.42 |
|
|
|
Sideswipe, same direction |
473 |
141 |
29.81 |
350,816 |
23,243 |
6.63 |
Sideswipe, opposite direction |
469 |
85 |
18.12 |
58,714 |
9,278 |
15.80 |
Rear–to–side |
88 |
45 |
51.14 |
|
|
|
Rear–to–rear |
6 |
3 |
50.00 |
3,788 |
686 |
18.11 |
Other |
75 |
18 |
24.00 |
|
|
|
Total |
15,363 |
3,477 |
22.63 |
3,941,488 |
747,998 |
18.98 |
No collision with motor vehicle |
22,048 |
8,063 |
36.57 |
1,762,624 |
447,073 |
25.36 |
Unknown |
176 |
13 |
7.39 |
8,626 |
499 |
5.78 |
Total |
37,587 |
11,553 |
30.74 |
5,712,738 |
1,195,570 |
20.93 |
Note: n represents frequency of crashes. Blank cells indicate that the code was not present in this database. |
Table 8. Frequency and number/percentage of SR crashes regarding type of collision in North Carolina.
Type of Collision |
FARS |
GES |
All Crashes |
SR Crashes |
All Crashes |
SR Crashes |
n |
n |
Percent |
n |
n |
Percent |
Collision with motor vehicle |
Rear–end |
2,253 |
927 |
41.15 |
1,730,195 |
603,805 |
34.90 |
Head–on |
3,959 |
655 |
16.54 |
116,689 |
13,456 |
11.53 |
Angle |
|
|
|
1,681,286 |
97,530 |
|
Front–to–side, same direction |
484 |
131 |
27.07 |
|
|
|
Front–to–side, opposite direction |
2,243 |
611 |
27.24 |
|
|
|
Front–to–side, right angle |
5,024 |
828 |
16.48 |
|
|
|
Front–to–side, unknown direction |
289 |
33 |
11.42 |
|
|
|
Sideswipe, same direction |
473 |
141 |
29.81 |
350,816 |
23,243 |
6.63 |
Sideswipe, opposite direction |
469 |
85 |
18.12 |
58,714 |
9,278 |
15.80 |
Rear–to–side |
88 |
45 |
51.14 |
|
|
|
Rear–to–rear |
6 |
3 |
50.00 |
3,788 |
686 |
18.11 |
Other |
75 |
18 |
24.00 |
|
|
|
Total |
15,363 |
3,477 |
22.63 |
3,941,488 |
747,998 |
18.98 |
No collision with motor vehicle |
22,048 |
8,063 |
36.57 |
1,762,624 |
447,073 |
25.36 |
Unknown |
176 |
13 |
7.39 |
8,626 |
499 |
5.78 |
Total |
37,587 |
11,553 |
30.74 |
5,712,738 |
1,195,570 |
20.93 |
Note: n represents frequency of crashes. |
Table 9. Frequency and number/percentage of SR crashes regarding type of collision in Ohio.
Type of Collision |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Collision with motor vehicle |
Rear–end |
1,236 |
0.90 |
4,530 |
3.29 |
5,766 |
4.19 |
131,817 |
95.81 |
137,583 |
100.00 |
Head–on |
205 |
2.88 |
714 |
10.03 |
919 |
12.91 |
6,202 |
87.09 |
7,121 |
100.00 |
Backing up |
10 |
0.11 |
70 |
0.80 |
80 |
0.91 |
8,668 |
99.09 |
8,748 |
100.00 |
Angle |
626 |
0.66 |
6,725 |
7.11 |
7,351 |
7.77 |
87,299 |
92.23 |
94,650 |
100.00 |
Sideswipe, same direction |
453 |
1.43 |
3,573 |
11.27 |
4,026 |
12.70 |
27,675 |
87.30 |
31,701 |
100.00 |
Sideswipe, opposite direction |
208 |
3.83 |
344 |
6.33 |
552 |
10.16 |
4,882 |
89.84 |
5,434 |
100.00 |
Left turn |
|
|
|
|
|
|
|
|
|
|
Right turn |
|
|
|
|
|
|
|
|
|
|
Other |
|
|
|
|
|
|
|
|
|
|
Total |
2,738 |
0.96 |
15,956 |
5.59 |
18,694 |
6.55 |
266,543 |
93.45 |
285,237 |
100.00 |
No collision with motor vehicle |
9,410 |
6.45 |
21,885 |
14.99 |
31,295 |
21.44 |
114,654 |
78.56 |
145,949 |
100.00 |
Unknown |
8 |
0.05 |
1,909 |
11.33 |
1,917 |
11.37 |
14,938 |
88.63 |
16,855 |
100.00 |
Total |
12,156 |
2.71 |
39,750 |
8.87 |
51,906 |
11.59 |
396,135 |
88.41 |
448,041 |
100.00 |
Note: n represents frequency of crashes. Blank cells indicate that the code was not present in this database |
As can be seen, regardless of the database or the definition used, SR crashes are primarily single–vehicle crashes. The only exception is in the over speed limit definition used in Ohio where sideswipe same direction crashes had a higher SR percentage but a much lower frequency. This finding would infer multilane highways. The databases differed with respect to which vehicle–to–vehicle crashes were most likely to be SR. GES and FARS data indicated rear–end crashes, while the State data indicated both types of sideswipe and head–on crashes.
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First Harmful Event
Table 10. Frequency and number/percentage of SR crashes regarding first harmful events.
First Harmful Event |
FARS |
GES |
All Crashes |
SR Crashes |
All Crashes |
SR Crashes |
n |
n |
Percent |
n |
n |
Percent |
Rollover/overturn |
4,243 |
1,772 |
41.76 |
134,466 |
58,419 |
43.45 |
Jackknife |
10 |
4 |
40.00 |
6,317 |
1,996 |
31.60 |
Other noncollision |
529 |
117 |
22.12 |
51,431 |
3,091 |
6.01 |
Collision with nonmotorist |
4,375 |
376 |
8.59 |
104,323 |
2,569 |
2.46 |
Collision with motor vehicle |
15,458 |
3,490 |
22.58 |
4,170,075 |
776,635 |
18.62 |
Collision with animal |
172 |
19 |
11.05 |
270,053 |
1,461 |
0.54 |
Collision with other nonfixed objects |
363 |
66 |
18.18 |
44,868 |
5,259 |
11.72 |
Collision with ground, ditch, culvert, embankment or boulder |
4,114 |
1,893 |
46.01 |
190,667 |
70,848 |
37.16 |
Collision with building, fence, wall, etc. |
658 |
324 |
49.24 |
121,563 |
42,527 |
34.98 |
Collision with bush or tree |
3,210 |
1,559 |
48.57 |
142,500 |
63,633 |
44.65 |
Collision with other fixed objects |
4,399 |
1,932 |
43.92 |
470,975 |
166,728 |
35.40 |
Unknown |
56 |
1 |
1.79 |
5,502 |
2,402 |
43.66 |
Total |
37,587 |
11,553 |
30.74 |
5,712,740 |
1,195,568 |
20.93 |
Note: n represents frequency of crashes. |
Table 11. Frequency and number/percentage of SR crashes regarding first harmful events in North Carolina.
First Harmful Event |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Rollover/
overturn |
1,055 |
11.36 |
3,933 |
42.37 |
4,988 |
53.73 |
4,295 |
46.27 |
9,283 |
100.00 |
Jackknife |
12 |
2.86 |
150 |
35.71 |
162 |
38.57 |
258 |
61.43 |
420 |
100.00 |
Other noncollision |
87 |
2.10 |
343 |
8.29 |
430 |
10.39 |
3,709 |
89.61 |
4,139 |
100.00 |
Collision with nonmotorist |
30 |
1.13 |
35 |
1.31 |
65 |
2.44 |
2,598 |
97.56 |
2,663 |
100.00 |
Collision with motor vehicle |
3,466 |
1.34 |
9,572 |
3.70 |
13,038 |
5.04 |
245,603 |
94.96 |
258,641 |
100.00 |
Collision with animal |
44 |
0.13 |
23 |
0.07 |
67 |
0.19 |
34,905 |
99.81 |
34,972 |
100.00 |
Collision with other nonfixed objects |
69 |
1.25 |
259 |
4.71 |
328 |
5.96 |
5,172 |
94.04 |
5,500 |
100.00 |
Ran off road |
1,901 |
8.84 |
7,254 |
33.73 |
9,155 |
42.57 |
12,350 |
57.43 |
21,505 |
100.00 |
Collision with other fixed objects |
6,130 |
8.93 |
28,359 |
41.30 |
34,489 |
50.22 |
34,182 |
49.78 |
68,671 |
100.00 |
Not coded |
8 |
1.89 |
16 |
3.78 |
24 |
5.67 |
399 |
94.33 |
423 |
100.00 |
Total |
12,802 |
3.15 |
49,944 |
12.29 |
62,746 |
15.45 |
343,471 |
84.55 |
406,217 |
100.00 |
Note: n represents frequency of crashes. |
Table 12. Frequency and number/percentage of SR crashes regarding first harmful events in Ohio.
First Harmful Event |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Rollover/
overturn |
127 |
10.03 |
257 |
20.30 |
384 |
30.33 |
882 |
69.67 |
1,266 |
100.00 |
Jackknife |
|
|
|
|
|
|
|
|
|
|
Other noncollision |
1,451 |
10.99 |
893 |
6.77 |
2,344 |
17.76 |
10,855 |
82.24 |
13,199 |
100.00 |
Collision with nonmotorist |
263 |
4.76 |
22 |
0.40 |
285 |
5.16 |
5,237 |
94.84 |
5,522 |
100.00 |
Collision with motor vehicle |
15,642 |
5.48 |
3,063 |
1.07 |
18,705 |
6.55 |
266,834 |
93.45 |
285,539 |
100.00 |
Collision with animal |
2,738 |
5.49 |
17 |
0.03 |
2,755 |
5.52 |
47,151 |
94.48 |
49,906 |
100.00 |
Collision with other nonfixed objects |
562 |
11.21 |
129 |
2.57 |
691 |
13.78 |
4,323 |
86.22 |
5,014 |
100.00 |
Ran off road |
|
|
|
|
|
|
|
|
|
|
Collision with other fixed objects |
8,301 |
11.73 |
16,524 |
23.36 |
24,825 |
35.09 |
45,915 |
64.91 |
70,740 |
100.00 |
Not coded |
1,593 |
9.45 |
324 |
1.92 |
1,917 |
11.37 |
14,938 |
88.63 |
16,855 |
100.00 |
Total |
30,677 |
6.85 |
21,229 |
4.74 |
51,906 |
11.59 |
396,135 |
88.41 |
448,041 |
100.00 |
Note: n represents frequency of crashes. Blank cells indicate that the code was not present in this database. |
Reinforcing the findings from table 7 through table 9, table 10 through table 12 show that regardless of database or definition, there was a consistent pattern indicating higher SR percentages and frequencies for various types of single–vehicle, off–roadway crashes. The SR percentage was much lower for vehicle–to–vehicle crashes and even lower for collisions with nonmotorists, which will be further examined in the next section.
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Nonmotorist Involvement
Table 13. Frequency and number/percentage of SR crashes regarding nonmotorist involvement.
Nonmotorist Involvement |
FARS |
GES |
All Crashes |
SR Crashes |
All Crashes |
SR Crashes |
n |
n |
Percent |
n |
n |
Percent |
No pedestrians/bicycles |
32,937 |
11,065 |
33.59 |
5,605,824 |
1,192,053 |
21.26 |
1+ pedestrians/bicycles |
4,646 |
486 |
10.46 |
|
|
|
Pedestrian accident |
|
|
|
59,483 |
3,084 |
5.18 |
Bicycle accident |
|
|
|
47,255 |
388 |
0.82 |
Wheelchair involved |
|
|
|
177 |
45 |
25.42 |
Total |
37,583 |
11,551 |
30.73 |
5,712,739 |
1,195,570 |
20.93 |
Note: n represents frequency of crashes. Blank cells indicate that the code was not present in this database. |
Table 14. Frequency and number/percentage of SR crashes regarding nonmotorist involvement in North Carolina.
Nonmotorist Involvement |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
No pedestrians/
bicycles |
12,761 |
3.17 |
49,860 |
12.37 |
62,621 |
15.53 |
340,492 |
84.47 |
403,113 |
100.00 |
1+ pedestrians/
bicycles |
41 |
1.32 |
84 |
2.71 |
125 |
4.03 |
2,979 |
95.97 |
3,104 |
100.00 |
Total |
12,802 |
3.15 |
49,944 |
12.29 |
62,746 |
15.45 |
343,471 |
84.55 |
406,217 |
100.00 |
Note: n represents frequency of crashes. |
Table 15. Frequency and number/percentage of SR crashes regarding nonmotorist involvement in North Carolina.
Nonmotorist Involvement |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
No pedestrians/
bicycles |
30,549 |
6.88 |
21,205 |
4.78 |
51,754 |
11.66 |
392,027 |
88.34 |
443,781 |
100.00 |
1+ pedestrians/
bicycles |
128 |
3.00 |
24 |
0.56 |
152 |
3.57 |
4,108 |
96.43 |
4,260 |
100.00 |
Total |
30,677 |
6.85 |
21,229 |
4.74 |
51,906 |
11.59 |
396,135 |
88.41 |
448,041 |
100.00 |
Note: n represents frequency of crashes. |
All databases and definitions of SR crashes indicated that the pedestrian and bicycle crashes were less likely to be SR than other types of crashes. The no pedestrians/bicycles crashes had two to five times the SR percentage. Note that in table 13, the GES and FARS data were probably more meaningful since the State–based findings were more rural; they did not include urban streets where many of the pedestrian and bicycle crashes would occur.
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FHWA-HRT-10-024
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