Development of a Speeding-Related Crash Typology
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RESULTS FOR SINGLE-VARIABLE ANALYSES
WHEN SR CRASHES ARE MOST LIKELY TO OCCUR
This section presents tables showing when SR crashes are most likely to occur. It shows the percentage of SR crashes by light condition, road surface, atmospheric condition, season, and day of the week.
Light Condition
Surface Condition
Weather
Season
Day of the Week
Light Condition
Table 42. Frequency and number/percentage of SR crashes regarding light condition.
Light Condition |
FARS |
GES |
All Crashes |
SR Crashes |
All Crashes |
SR Crashes |
n |
n |
Percent |
n |
n |
Percent |
Daylight |
18,973 |
4,950 |
26.09 |
3,978,106 |
805,809 |
20.26 |
Dark |
11,215 |
4,124 |
36.77 |
671,326 |
168,480 |
25.10 |
Dark but lighted |
5,564 |
1,963 |
35.28 |
813,033 |
169,334 |
20.83 |
Dawn |
710 |
219 |
30.85 |
86,112 |
20,785 |
24.14 |
Dusk |
848 |
263 |
31.01 |
131,615 |
27,809 |
21.13 |
Unknown |
277 |
34 |
12.27 |
32,548 |
3,353 |
10.30 |
Total |
37,587 |
11,553 |
30.74 |
5,712,740 |
1,195,570 |
20.93 |
Note: n represents frequency of crashes. |
Table 43. Frequency and number/percentage of SR crashes regarding light condition in North Carolina.
Category |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Daylight |
6,416 |
2.34 |
30,270 |
11.04 |
36,686 |
13.38 |
237,423 |
86.62 |
274,109 |
100.00 |
Dark |
4,956 |
5.83 |
15,348 |
18.06 |
20,304 |
23.89 |
64,691 |
76.11 |
84,995 |
100.00 |
Dark but lighted |
878 |
2.95 |
1,866 |
6.27 |
2,744 |
9.22 |
27,026 |
90.78 |
29,770 |
100.00 |
Dawn |
254 |
3.61 |
1,237 |
17.57 |
1,491 |
21.17 |
5,551 |
78.83 |
7,042 |
100.00 |
Dusk |
267 |
2.77 |
1,115 |
11.58 |
1,382 |
14.35 |
8,249 |
85.65 |
9,631 |
100.00 |
Unknown |
31 |
4.63 |
108 |
16.12 |
139 |
20.75 |
531 |
79.25 |
670 |
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 44. Frequency and number/percentage of SR crashes regarding light condition in Ohio.
Category |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Daylight |
16,918 |
5.78 |
11,895 |
4.07 |
28,813 |
9.85 |
263,681 |
90.15 |
292,494 |
100.00 |
Dark |
6,007 |
8.33 |
6,875 |
9.53 |
12,882 |
17.86 |
59,259 |
82.14 |
72,141 |
100.00 |
Dark but lighted |
6,031 |
10.62 |
1,207 |
2.12 |
7,238 |
12.74 |
49,567 |
87.26 |
56,805 |
100.00 |
Dawn |
648 |
6.79 |
627 |
6.57 |
1,275 |
13.35 |
8,273 |
86.65 |
9,548 |
100.00 |
Dusk |
700 |
6.41 |
443 |
4.06 |
1,143 |
10.46 |
9,781 |
89.54 |
10,924 |
100.00 |
Unknown |
373 |
6.09 |
182 |
2.97 |
555 |
9.06 |
5,574 |
90.94 |
6,129 |
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. |
With minor exceptions, all databases and definitions in table 42 through table 44 indicated that crashes at night had the highest percentage of SR crashes. The findings in the "Dark but lighted" category varied between databases.
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Surface Condition
Table 45. Frequency and number/percentage of SR crashes regarding surface condition.
Surface Condition |
FARS |
GES |
All Crashes |
SR Crashes |
All Crashes |
SR Crashes |
n |
n |
Percent |
n |
n |
Percent |
Dry |
31,241 |
9,196 |
29.44 |
4,401,379 |
774,151 |
17.59 |
Wet |
4,768 |
1,627 |
34.12 |
866,361 |
234,023 |
27.01 |
Snow or slush |
569 |
299 |
52.55 |
209,910 |
103,822 |
49.46 |
Ice |
547 |
317 |
57.95 |
153,079 |
69,146 |
45.17 |
Sand, dirt, or oil |
48 |
28 |
58.33 |
7,336 |
2,114 |
28.82 |
Other |
|
|
|
9,231 |
3,738 |
40.49 |
Unknown |
|
|
|
65,444 |
8,575 |
13.10 |
Total |
37,587 |
11,553 |
30.74 |
5,712,740 |
1,195,569 |
20.93 |
Note: n represents frequency of crashes. |
Table 46. Frequency and number/percentage of SR crashes regarding surface condition in North Carolina.
Surface Condition |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Dry |
10,791 |
3.50 |
15,558 |
5.04 |
26,349 |
8.54 |
282,322 |
91.46 |
308,671 |
100.00 |
Wet |
1,868 |
2.38 |
21,025 |
26.75 |
22,893 |
29.13 |
55,703 |
70.87 |
78,596 |
100.00 |
Snow or slush |
24 |
0.30 |
5,845 |
73.30 |
5,869 |
73.60 |
2,105 |
26.40 |
7,974 |
100.00 |
Ice |
73 |
0.73 |
7,304 |
73.34 |
7,377 |
74.07 |
2,582 |
25.93 |
9,959 |
100.00 |
Sand, dirt, oil, or other |
20 |
4.36 |
170 |
37.04 |
190 |
41.39 |
269 |
58.61 |
459 |
100.00 |
Unknown |
26 |
4.66 |
42 |
7.53 |
68 |
12.19 |
490 |
87.81 |
558 |
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 47. Frequency and number/percentage of SR crashes regarding surface condition in Ohio.
Surface Condition |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Dry |
22,418 |
7.39 |
4,231 |
1.40 |
26,649 |
8.79 |
276,565 |
91.21 |
303,214 |
100.00 |
Wet |
6,768 |
6.66 |
6,388 |
6.28 |
13,156 |
12.94 |
88,517 |
87.06 |
101,673 |
100.00 |
Snow or slush |
753 |
2.91 |
6,398 |
24.72 |
7,151 |
27.63 |
18,734 |
72.37 |
25,885 |
100.00 |
Ice |
359 |
3.22 |
3,259 |
29.26 |
3,618 |
32.48 |
7,521 |
67.52 |
11,139 |
100.00 |
Sand, dirt, oil, or other |
211 |
6.26 |
900 |
26.72 |
1,111 |
32.99 |
2,257 |
67.01 |
3,368 |
100.00 |
Unknown |
168 |
6.08 |
53 |
1.92 |
221 |
8.00 |
2,541 |
92.00 |
2,762 |
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. |
The surface condition variable was the first of two variables (the second being weather) in which the findings from the combined versus over speed limit definitions consistently differed (see table 45 through table 47). The combined definition for all databases indicated higher SR crash percentages for snow and ice conditions. In contrast, the over speed limit definition for both States showed that the dry condition had the highest percentage of SR crashes. This is not unexpected, as an investigating officer may be likely to conclude that most drivers go too fast for conditions even without speeding per se in snowy and icy conditions. One conclusion that might be drawn is that SR crashes in snowy and icy conditions might be better treated by roadway (e.g., snow and ice removal) or vehicles treatments rather than by enforcement or education efforts.
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Weather
Table 48. Frequency and number/percentage of SR crashes regarding weather.
Weather |
FARS |
GES |
All Crashes |
SR Crashes |
All Crashes |
SR Crashes |
n |
n |
Percent |
n |
n |
Percent |
No adverse atmospheric conditions |
33,036 |
9,907 |
29.99 |
4,808,369 |
899,217 |
18.70 |
Rain |
2,805 |
992 |
35.37 |
547,389 |
156,006 |
28.50 |
Sleet |
131 |
71 |
54.20 |
17,339 |
7,019 |
40.48 |
Snow |
616 |
307 |
49.84 |
230,049 |
115,887 |
50.37 |
Fog |
420 |
145 |
34.52 |
22,127 |
4,862 |
21.97 |
Rain and fog |
31 |
13 |
41.94 |
1,819 |
359 |
19.74 |
Sleet and fog |
10 |
7 |
70.00 |
503 |
241 |
47.91 |
Other; smog, smoke, blowing sand, snow, dust, crosswind, etc. |
184 |
50 |
27.17 |
31,065 |
6,962 |
22.41 |
Unknown |
354 |
61 |
17.23 |
54,079 |
5,017 |
9.28 |
Total |
37,587 |
11,553 |
30.74 |
5,712,739 |
1,195,570 |
20.93 |
Note: n represents frequency of crashes. |
Table 49. Frequency and number/percentage of SR crashes regarding weather in North Carolina.
Weather |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
No adverse atmospheric conditions |
11,410 |
3.44 |
22,922 |
6.91 |
34,332 |
10.34 |
297,589 |
89.66 |
331,921 |
100.00 |
Rain |
1,164 |
2.01 |
17,773 |
30.67 |
18,937 |
32.68 |
39,003 |
67.32 |
57,940 |
100.00 |
Sleet |
21 |
0.58 |
2,528 |
69.55 |
2,549 |
70.12 |
1,086 |
29.88 |
3,635 |
100.00 |
Snow |
26 |
0.32 |
5,636 |
70.04 |
5,662 |
70.36 |
2,385 |
29.64 |
8,047 |
100.00 |
Fog |
151 |
4.18 |
799 |
22.14 |
950 |
26.32 |
2,659 |
73.68 |
3,609 |
100.00 |
Rain and fog |
11 |
2.60 |
170 |
40.19 |
181 |
42.79 |
242 |
57.21 |
423 |
100.00 |
Sleet and fog |
3 |
9.68 |
18 |
58.06 |
21 |
67.74 |
10 |
32.26 |
31 |
100.00 |
Other; smoke, dust, or wind |
16 |
2.62 |
98 |
16.04 |
114 |
18.66 |
497 |
81.34 |
611 |
100.00 |
Unknown |
|
|
|
|
|
|
|
|
|
|
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. Blank cells indicate that the code was not present in this database. |
Table 50. Frequency and number/percentage of SR crashes regarding weather in Ohio.
Weather |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
No adverse atmospheric conditions |
24,925 |
7.23 |
8,027 |
2.33 |
32,952 |
9.56 |
311,655 |
90.44 |
344,607 |
100.00 |
Rain |
3,691 |
6.69 |
3,670 |
6.65 |
7,361 |
13.35 |
47,794 |
86.65 |
55,155 |
100.00 |
Sleet |
|
|
|
|
|
|
|
|
|
|
Snow |
1,285 |
3.73 |
7,671 |
22.28 |
8,956 |
26.01 |
25,480 |
73.99 |
34,436 |
100.00 |
Fog |
259 |
7.11 |
281 |
7.71 |
540 |
14.81 |
3,105 |
85.19 |
3,645 |
100.00 |
Rain and fog |
|
|
|
|
|
|
|
|
|
|
Sleet and fog |
|
|
|
|
|
|
|
|
|
|
Other; smoke, dust, or wind |
278 |
4.47 |
1,489 |
23.94 |
1,767 |
28.41 |
4,453 |
71.59 |
6,220 |
100.00 |
Unknown |
239 |
6.01 |
91 |
2.29 |
330 |
8.30 |
3,648 |
91.70 |
3,978 |
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. |
The findings from table 48 through table 50 support those from table 45 through table 47. Using the combined definition of SR (predominantly too fast for conditions), adverse weather conditions had a higher SR crash percentage. Using the over speed limit definition, nonadverse conditions had a higher SR crash percentage.
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Season
Table 51. Frequency and number/percentage of SR crashes regarding season.
Season |
FARS |
GES |
All Crashes |
SR Crashes |
All Crashes |
SR Crashes |
n |
n |
Percent |
n |
n |
Percent |
Winter |
8,269 |
2,540 |
30.72 |
1,484,529 |
355,032 |
23.92 |
Spring |
9,085 |
2,813 |
30.96 |
1,395,434 |
278,033 |
19.92 |
Summer |
10,224 |
3,153 |
30.84 |
1,379,243 |
275,118 |
19.95 |
Fall |
10,009 |
3,047 |
30.44 |
1,453,533 |
287,387 |
19.77 |
Total |
37,587 |
11,553 |
30.74 |
5,712,739 |
1,195,570 |
20.93 |
Note: n represents frequency of crashes. |
Table 52. Frequency and number/percentage of SR crashes regarding season in North Carolina.
Season |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Winter |
2,684 |
2.61 |
19,791 |
19.24 |
22,475 |
21.85 |
80,405 |
78.15 |
102,880 |
100.00 |
Spring |
3,438 |
3.57 |
9,085 |
9.42 |
12,523 |
12.99 |
83,889 |
87.01 |
96,412 |
100.00 |
Summer |
3,463 |
3.53 |
11,077 |
11.28 |
14,540 |
14.80 |
83,695 |
85.20 |
98,235 |
100.00 |
Fall |
3,217 |
2.96 |
9,991 |
9.19 |
13,208 |
12.15 |
95,482 |
87.85 |
108,690 |
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 53. Frequency and number/percentage of SR crashes regarding season in Ohio.
Season |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Winter |
7,049 |
5.78 |
11,304 |
9.27 |
18,353 |
15.05 |
103,560 |
84.95 |
121,913 |
100.00 |
Spring |
7,584 |
7.31 |
4,101 |
3.95 |
11,685 |
11.26 |
92,061 |
88.74 |
103,746 |
100.00 |
Summer |
7,803 |
7.53 |
2,545 |
2.46 |
10,348 |
9.99 |
93,233 |
90.01 |
103,581 |
100.00 |
Fall |
8,241 |
6.94 |
3,279 |
2.76 |
11,520 |
9.70 |
107,281 |
90.30 |
118,801 |
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. |
While GES and FARS data in table 51 showed essentially no differences between seasons for total SR, the State data using the same definition in table 52 and table 53 showed that winter had a higher SR percentage. This could result from the States having more snowy and icy conditions in winter and thus more SR crashes resulting from driving too fast for the condition than the average State represented in FARS and GES. The over speed limit category showed slight differences between seasons.
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Day of the Week
Table 54. Frequency and number/percentage of SR crashes regarding day of the week.
Day of the Week |
FARS |
GES |
All Crashes |
SR Crashes |
All Crashes |
SR Crashes |
n |
n |
Percent |
n |
n |
Percent |
Weekend |
12,842 |
4,492 |
34.98 |
1,320,236 |
289,867 |
21.96 |
Weekday |
24,735 |
7,059 |
28.54 |
4,392,503 |
905,703 |
20.62 |
Unknown |
10 |
2 |
20.00 |
0 |
0 |
0.00 |
Total |
37,587 |
11,553 |
30.74 |
5,712,739 |
1,195,570 |
20.93 |
Note: n represents frequency of crashes. |
Table 55. Frequency and number/percentage of SR crashes regarding day of the week in North Carolina.
Day of the Week |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Weekend |
4,583 |
4.60 |
14,938 |
15.00 |
19,521 |
19.60 |
80,097 |
80.40 |
99,618 |
100.00 |
Weekday |
8,219 |
2.68 |
35,006 |
11.42 |
43,225 |
14.10 |
263,374 |
85.90 |
306,599 |
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 56. Frequency and number/percentage of SR crashes regarding day of the week in Ohio.
Day of the Week |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Weekend |
9,065 |
8.75 |
6,728 |
6.50 |
15,793 |
15.25 |
87,790 |
84.75 |
103,583 |
100.00 |
Weekday |
21,612 |
6.27 |
14,501 |
4.21 |
36,113 |
10.48 |
308,345 |
89.52 |
344458 |
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. |
As seen in table 54 through table 56, the percentage of SR crashes was highest on the weekends except for GES in which no difference was seen.
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FHWA-HRT-10-024
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