Development of a Speeding-Related Crash Typology
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RESULTS FOR SINGLE-VARIABLE ANALYSES
WHERE SR CRASHES OCCUR
In this section, tables are presented that show the frequencies and percentages of SR crashes for variables related to the location of crashes. They show the percentage of SR crashes by location of the first harmful event, relationship to junction, functional class, speed limit, number of travel lanes, AADT per lane, roadway alignment, roadway profile, and work zone.
Location of First Harmful Event
Relationship to Junction
Functional Class
Speed Limit
Number of Travel Lanes
AADT Per Lane
Roadway Alignment
Roadway Profile
Work Zone
Location of First Harmful Event
Table 16. Frequency and number/percentage of SR crashes regarding the location of the first harmful event.
Location of First Harmful Event |
FARS |
GES |
All Crashes |
SR Crashes |
All Crashes |
SR Crashes |
n |
n |
Percent |
n |
n |
Percent |
On roadway |
20,936 |
4,241 |
20.26 |
4,628,618 |
790,870 |
17.09 |
Treated roadside |
3,922 |
1,552 |
39.57 |
195,702 |
74,028 |
37.83 |
Untreated roadside |
12,534 |
5,751 |
45.88 |
881,274 |
329,272 |
37.36 |
Unknown |
195 |
9 |
4.62 |
7,145 |
1,400 |
19.59 |
Total |
37,587 |
11,553 |
30.74 |
5,712,739 |
1,195,570 |
20.93 |
Note: n represents frequency of crashes. |
Table 17. Frequency and number/percentage of SR crashes regarding the location of the first harmful event in North Carolina.
Location of 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 |
On roadway |
5,394 |
1.66 |
17,162 |
5.28 |
22,556 |
6.94 |
302,407 |
93.06 |
324,963 |
100.00 |
Off roadway |
|
|
|
|
|
|
|
|
|
|
Treated roadside |
4,561 |
8.54 |
22,195 |
41.55 |
26,756 |
50.09 |
26,658 |
49.91 |
53,414 |
100.00 |
Untreated roadside |
2,846 |
10.24 |
10,578 |
38.06 |
13,424 |
48.30 |
14,370 |
51.70 |
27,794 |
100.00 |
Unknown |
1 |
2.17 |
9 |
19.57 |
10 |
21.74 |
36 |
78.26 |
46 |
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. Blank cells indicate that the code was not present in this database. |
Table 18. Frequency and number/percentage of SR crashes regarding the location of the first harmful event in Ohio.
Location of 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 |
On roadway |
22,646 |
6.00 |
4,882 |
1.29 |
27,528 |
7.29 |
349,884 |
92.71 |
377,412 |
100.00 |
Off roadway |
6,627 |
11.21 |
15,106 |
25.56 |
21,733 |
36.77 |
37,370 |
63.23 |
59,103 |
100.00 |
Treated roadside |
|
|
|
|
|
|
|
|
|
|
Untreated roadside |
|
|
|
|
|
|
|
|
|
|
Unknown |
1,404 |
12.18 |
1,241 |
10.77 |
2,645 |
22.95 |
8,881 |
77.05 |
11,526 |
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 |
These tables again support the trend that off–roadway crashes (which are predominantly single vehicle) are more related to speed than on–roadway crashes.
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Relationship to Junction
Table 19. Frequency and number/percentage of SR crashes regarding the relationship to the junction.
Relationship to Junction |
FARS |
GES |
All Crashes |
SR Crashes |
All Crashes |
SR Crashes |
n |
n |
Percent |
n |
n |
Percent |
Not related to junction |
26,966 |
9,354 |
34.69 |
2,491,891 |
672,697 |
27.00 |
Intersection related |
8,078 |
1,510 |
18.69 |
2,340,179 |
383,900 |
16.40 |
Other junctions |
1,347 |
291 |
21.60 |
601,811 |
66,438 |
11.04 |
Interchange area |
1,007 |
391 |
38.83 |
210,542 |
64,248 |
30.52 |
Unknown |
189 |
7 |
3.70 |
68,316 |
8,286 |
12.13 |
Total |
37,587 |
11,553 |
30.74 |
5,712,739 |
1,195,569 |
20.93 |
Note: n represents frequency of crashes. |
Table 20. Frequency and number/percentage of SR crashes regarding the relationship to the junction in North Carolina.
Relationship to Junction |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Not related to junction |
9,387 |
3.96 |
40,788 |
17.20 |
50,175 |
21.16 |
186,962 |
78.84 |
237,137 |
100.00 |
Intersection related |
1,580 |
1.64 |
3,873 |
4.03 |
5,453 |
5.67 |
90,709 |
94.33 |
96,162 |
100.00 |
Interchange area |
160 |
1.69 |
1,071 |
11.31 |
1,231 |
13.00 |
8,237 |
87.00 |
9,468 |
100.00 |
Other |
1,206 |
4.26 |
2,384 |
8.41 |
3,590 |
12.67 |
24,750 |
87.33 |
28,340 |
100.00 |
Unknown |
469 |
1.34 |
1,828 |
5.21 |
2,297 |
6.54 |
32,813 |
93.46 |
35,110 |
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 21. Frequency and number/percentage of SR crashes regarding the relationship to the junction in Ohio.
Relationship to Junction |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Not related to junction |
22,028 |
8.39 |
19,722 |
7.51 |
41,750 |
15.90 |
220,871 |
84.10 |
262,621 |
100.00 |
Intersection related |
6,845 |
5.03 |
956 |
0.70 |
7,801 |
5.74 |
128,203 |
94.26 |
136,004 |
100.00 |
Interchange area |
802 |
2.94 |
366 |
1.34 |
1,168 |
4.28 |
26,148 |
95.72 |
27,316 |
100.00 |
Other |
851 |
4.32 |
143 |
0.73 |
994 |
5.05 |
18,705 |
94.95 |
19,699 |
100.00 |
Unknown |
151 |
6.29 |
42 |
1.75 |
193 |
8.04 |
2,208 |
91.96 |
2,401 |
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. |
Both the North Carolina and Ohio data indicated that the "Not related to junction" category had the highest percentage of SR crashes. Since these crashes would be predominately run–off–road crashes, this supports the earlier findings showing high SR percentages and frequencies in off–roadway crashes. Interestingly, both the FARS and GES data indicated that the "Interchange area" category had the highest percentage of SR crashes. As noted previously, the category in both FARS and GES with the second highest percentage was "Not related to junction," which represented crashes occurring on roadway sections between intersections or interchanges and would contain off–roadway crashes. This category contained 10 times the number of interchange crashes in the GES file and 23 times the number of interchange crashes in the FARS data.
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Functional Class
Table 22. Frequency and number/percentage of SR crashes regarding functional class.
Functional Class |
FARS |
GES |
All Crashes |
SR Crashes |
All Crashes |
SR Crashes |
n |
n |
Percent |
n |
n |
Percent |
Interstate |
|
|
|
476,336 |
168,336 |
35.34 |
Noninterstate |
|
|
|
5,234,875 |
1,027,500 |
19.63 |
Rural interstate |
2,600 |
803 |
30.88 |
|
|
|
Rural principal arterial other |
3,866 |
901 |
23.31 |
|
|
|
Rural minor arterial |
3,736 |
1,052 |
28.16 |
|
|
|
Rural major collector |
5,008 |
1,767 |
35.28 |
|
|
|
Rural minor collector |
1,375 |
549 |
39.93 |
|
|
|
Rural local road |
3,754 |
1,490 |
39.69 |
|
|
|
Unknown rural |
240 |
117 |
48.75 |
|
|
|
Urban interstate |
2,231 |
711 |
31.87 |
|
|
|
Urban freeway/
expressway |
1,446 |
485 |
33.54 |
|
|
|
Urban other principal arterial |
4,400 |
1,003 |
22.80 |
|
|
|
Urban minor arterial |
3,206 |
915 |
28.54 |
|
|
|
Urban collector |
1,193 |
454 |
38.06 |
|
|
|
Urban local street |
2,884 |
994 |
34.47 |
|
|
|
Unknown urban |
72 |
30 |
41.67 |
|
|
|
Unknown |
1,576 |
282 |
17.89 |
|
|
|
Total |
37,587 |
11,553 |
30.74 |
5,711,211 |
1,195,836 |
20.94 |
Note: n represents frequency of crashes. Blank cells indicate that the code was not present in this database. |
Table 23. Frequency and number/percentage of SR crashes regarding functional class in North Carolina.
Functional Class |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Rural principal arterial interstate |
500 |
4.02 |
4 |
0.03 |
4,224 |
33.96 |
8,214 |
66.04 |
12,438 |
100.00 |
Rural principal arterial other |
931 |
4.08 |
3,661 |
16.04 |
4,592 |
20.12 |
18,235 |
79.88 |
22,827 |
100.00 |
Rural minor arterial |
703 |
3.13 |
2,454 |
10.93 |
3,157 |
14.06 |
19,296 |
85.94 |
22,453 |
100.00 |
Rural major collector |
1,826 |
4.14 |
6,520 |
14.78 |
8,346 |
18.92 |
35,774 |
81.08 |
44,120 |
100.00 |
Rural minor collector |
1,429 |
6.01 |
5,156 |
21.69 |
6,585 |
27.70 |
17,191 |
72.30 |
23,776 |
100.00 |
Rural local road or street |
2,458 |
6.63 |
9,156 |
24.70 |
11,614 |
31.33 |
25,454 |
68.67 |
37,068 |
100.00 |
Urban principal arterial interstate |
796 |
2.40 |
5,770 |
17.36 |
6,566 |
19.76 |
26,662 |
80.24 |
33,228 |
100.00 |
Urban principal arterial other freeway or expressway |
235 |
2.05 |
1,338 |
11.70 |
1,573 |
13.75 |
9,863 |
86.25 |
11,436 |
100.00 |
Urban principal arterial other |
862 |
1.02 |
2,770 |
3.29 |
3,632 |
4.32 |
80,504 |
95.68 |
84,136 |
100.00 |
Urban minor arterial |
1,200 |
1.76 |
3,560 |
5.21 |
4,760 |
6.96 |
63,591 |
93.04 |
68,351 |
100.00 |
Urban collector |
646 |
3.68 |
1,826 |
10.40 |
2,472 |
14.08 |
15,080 |
85.92 |
17,552 |
100.00 |
Urban local road or street |
1,149 |
4.39 |
3,741 |
14.30 |
4,890 |
18.69 |
21,270 |
81.31 |
26,160 |
100.00 |
Unknown |
67 |
2.51 |
268 |
10.03 |
335 |
12.54 |
2,337 |
87.46 |
2,672 |
100.00 |
Total |
12,802 |
3.15 |
46,224 |
11.38 |
62,746 |
15.45 |
343,471 |
84.55 |
406,217 |
100.00 |
Note: n represents frequency of crashes. |
Table 24. Frequency and number/percentage of SR crashes regarding functional class in Ohio.
Functional Class |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Rural principal arterial interstate |
3,591 |
16.65 |
3,606 |
16.72 |
7,197 |
33.37 |
14,369 |
66.63 |
21,566 |
100.00 |
Rural principal arterial other |
2,280 |
7.97 |
2,262 |
7.91 |
4,542 |
15.89 |
24,051 |
84.11 |
28,593 |
100.00 |
Rural minor arterial |
1,692 |
5.36 |
2,431 |
7.70 |
4,123 |
13.06 |
27,440 |
86.94 |
31,563 |
100.00 |
Rural major collector |
3,165 |
5.62 |
6,299 |
11.19 |
9,464 |
16.82 |
46,815 |
83.18 |
56,279 |
100.00 |
Rural minor collector |
188 |
5.15 |
582 |
15.94 |
770 |
21.09 |
2,881 |
78.91 |
3,651 |
100.00 |
Rural local road or street |
4 |
7.55 |
9 |
16.98 |
13 |
24.53 |
40 |
75.47 |
53 |
100.00 |
Urban principal arterial interstate |
7,525 |
10.48 |
3,153 |
4.39 |
10,678 |
14.87 |
61,142 |
85.13 |
71,820 |
100.00 |
Urban principal arterial other freeway or expressway |
1,500 |
8.09 |
925 |
4.99 |
2,425 |
13.08 |
16,110 |
86.92 |
18,535 |
100.00 |
Urban principal arterial other |
6,930 |
4.83 |
1,059 |
0.74 |
7,989 |
5.57 |
135,464 |
94.43 |
143,453 |
100.00 |
Urban minor arterial |
3,358 |
5.22 |
662 |
1.03 |
4,020 |
6.2% |
60,289 |
93.75 |
64,309 |
100.00 |
Urban collector |
269 |
4.98 |
216 |
4.00 |
485 |
8.97 |
4,921 |
91.03 |
5,406 |
100.00 |
Urban local road or street |
11 |
7.53 |
5 |
3.42 |
16 |
10.96 |
130 |
89.04 |
146 |
100.00 |
Unknown |
164 |
6.15 |
20 |
0.75 |
184 |
6.90 |
2,483 |
93.10 |
2,667 |
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. |
There was some inconsistency in the findings in table 22 through table 24. GES did not have a functional class variable, but when all interstates were compared to all noninterstates, the interstates had a higher percentage of SR crashes than noninterstates (35 percent versus 20 percent). This differed from the FARS data in which the detailed functional classes were presented and in which higher SR crash percentages were found in the minor collector and local roads classes. In general, higher SR percentages were seen for rural roads versus urban roads when comparing similar rural and urban classes in both State databases and with both definitions. A much smaller difference was seen in the FARS data when all rural classes were combined and compared to the total SR for all urban classes combined (30 percent versus 28 percent). This could be because the State data did not include the local urban streets and thus included more rural roads in nature. For the State systems in table 23 and table 24, the combined definition showed that rural interstates had the highest percentage of SR crashes. However, the over speed limit definition of SR illustrated a difference between North Carolina and Ohio, which may reflect true differences in speeding. North Carolina data indicated that speeding over the posted limit was a bigger problem on local and minor roads, while in Ohio, speeding was a bigger problem on interstates and arterials. One possible explanation is that Ohio has lower posted speed limits than North Carolina (i.e., 65 mi/h versus 70 mi/h on rural roads and 55 mi/h versus 60 mi/h on urban roads), which might lead to more speeding over the posted limit.
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Speed Limit
Table 25. Frequency and number/percentage of SR crashes regarding to speed limit.
Speed Limit (mi/h) |
FARS |
GES |
All Crashes |
SR Crashes |
All Crashes |
SR Crashes |
n |
n |
Percent |
n |
n |
Percent |
£ |
1,684 |
630 |
37.41 |
627,227 |
104,256 |
16.62 |
30–35 |
5,878 |
2,075 |
35.30 |
1,454,310 |
269,951 |
18.56 |
40–45 |
7,932 |
2,492 |
31.42 |
1,308,034 |
294,008 |
22.48 |
50–60 |
14,514 |
4,197 |
28.92 |
1,041,497 |
241,486 |
23.19 |
≥ 65 |
6,503 |
1,885 |
28.99 |
421,216 |
140,836 |
33.44 |
No limit |
118 |
39 |
33.05 |
34,984 |
2,298 |
6.57 |
Unknown |
953 |
231 |
24.24 |
823,860 |
142,735 |
17.33 |
Total |
37,582 |
11,549 |
30.73 |
5,711,128 |
1,195,570 |
20.93 |
Note: n represents frequency of crashes. |
Table 26. Frequency and number/percentage of SR crashes regarding speed limit in North Carolina.
Speed Limit (mi/h) |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
£ 25 |
114 |
2.41 |
195 |
4.12 |
309 |
6.53 |
4,423 |
93.47 |
4,732 |
100.00 |
30–35 |
1,723 |
1.95 |
4,289 |
4.86 |
6,012 |
6.82 |
82,156 |
93.18 |
88,168 |
100.00 |
40–45 |
1,522 |
1.84 |
4,849 |
5.85 |
6,371 |
7.69 |
76,449 |
92.31 |
82,820 |
100.00 |
50–60 |
8,425 |
4.25 |
32,984 |
16.64 |
41,409 |
20.88 |
156,870 |
79.12 |
198,279 |
100.00 |
≥ 65 |
1,018 |
3.16 |
7,627 |
23.67 |
8,645 |
26.83 |
23,573 |
73.17 |
32,218 |
100.00 |
Unknown |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0.00 |
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 27. Frequency and number/percentage of SR crashes regarding speed limit in Ohio.
Speed Limit (mi/h) |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
£ 25 |
2928 |
7.75 |
106 |
0.28 |
3034 |
8.03 |
34,752 |
91.97 |
37786 |
100.00 |
30–35 |
5488 |
4.76 |
743 |
0.64 |
6231 |
5.41 |
108,970 |
94.59 |
115201 |
100.00 |
40–45 |
1951 |
3.81 |
1,319 |
2.58 |
3270 |
6.39 |
47,931 |
93.61 |
51201 |
100.00 |
50–60 |
11156 |
6.80 |
11,476 |
7.00 |
22632 |
13.80 |
141,373 |
86.20 |
164005 |
100.00 |
≥ 65 |
8986 |
11.64 |
7,565 |
9.80 |
16551 |
21.45 |
60,617 |
78.55 |
77168 |
100.00 |
Unknown |
168 |
6.27 |
20 |
0.75 |
188 |
7.01 |
2,492 |
92.99 |
2,680 |
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. |
There is some inconsistency in the findings found in table 25 through table 27. In general, there was agreement between GES, North Carolina, and Ohio when the combined definition was used–the percentage of SR crashes increased as speed limit increased. The fatal crashes were different with FARS, showing a less clear trend and a slightly higher percentage of SR crashes for the lower limits (i.e., 35 mi/h and below). The over speed limit definition produced different results in the two States, with North Carolina showing a higher percentage of SR crashes for the 50–60 mi/h speed limits and Ohio showing a higher percentage of SR crashes for the ≥ 65 mi/h speed limits.
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Number of Travel Lanes
Table 28. Frequency and number/percentage of SR crashes regarding number of travel lanes.
Number of Travel Lanes |
FARS |
GES |
All Crashes |
SR Crashes |
All Crashes |
SR Crashes |
n |
n |
Percent |
n |
n |
Percent |
One lane |
455 |
201 |
44.18 |
140,060 |
36,464 |
26.03 |
Two lanes |
21,922 |
7,286 |
33.24 |
1,905,333 |
430,387 |
22.59 |
Three lanes |
510 |
136 |
26.67 |
253,311 |
48,508 |
19.15 |
Four lanes |
8,840 |
2,352 |
26.61 |
949,315 |
216,818 |
22.84 |
Five lanes |
196 |
65 |
33.16 |
403,429 |
100,090 |
24.81 |
Six lanes |
2,367 |
626 |
26.45 |
453,888 |
101,775 |
22.42 |
Seven or more lanes |
2,806 |
777 |
27.69 |
345,821 |
92,127 |
26.64 |
Unknown lanes |
491 |
110 |
22.40 |
1,261,582 |
169,399 |
13.43 |
Total |
37,587 |
11,553 |
30.74 |
5,712,739 |
1,195,568 |
20.93 |
Note: n represents frequency of crashes. |
Table 29. Frequency and number/percentage of SR crashes regarding number of travel lanes in North Carolina.
Number of Travel Lanes |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
£ Two lanes |
9,354 |
4.20 |
4 |
0.00 |
42,085 |
18.90 |
180,563 |
81.10 |
222,648 |
100.00 |
Three lanes |
45 |
1.21 |
178 |
4.80 |
223 |
6.01 |
3,487 |
93.99 |
3,710 |
100.00 |
Four lanes |
2,798 |
1.95 |
12,824 |
8.95 |
15,622 |
10.91 |
127,610 |
89.09 |
143,232 |
100.00 |
Five lanes |
14 |
0.87 |
74 |
4.60 |
88 |
5.48 |
1,519 |
94.52 |
1,607 |
100.00 |
Six lanes |
419 |
1.53 |
2,512 |
9.16 |
2,931 |
10.68 |
24,506 |
89.32 |
27,437 |
100.00 |
Seven lanes |
20 |
3.11 |
185 |
28.77 |
205 |
31.88 |
438 |
68.12 |
643 |
100.00 |
≥ Eight lanes |
152 |
2.19 |
1,440 |
20.75 |
1,592 |
22.94 |
5,348 |
77.06 |
6,940 |
100.00 |
Unknown |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0.00 |
Total |
12,802 |
3.15 |
17,217 |
4.24 |
62,746 |
15.45 |
343,471 |
84.55 |
406,217 |
100.00 |
Note: n represents frequency of crashes. |
Table 30. Frequency and number/percentage of SR crashes regarding number of travel lanes in Ohio.
Number of Travel Lanes |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
£ Two lanes |
9,206 |
5.30 |
11,129 |
6.40 |
20,335 |
11.70 |
153,431 |
88.30 |
173,766 |
100.00 |
Three lanes |
194 |
5.19 |
61 |
1.63 |
255 |
6.82 |
3,484 |
93.18 |
3,739 |
100.00 |
Four lanes |
14,002 |
7.10 |
7,249 |
3.67 |
21,251 |
10.77 |
176,006 |
89.23 |
197,257 |
100.00 |
Five lanes |
334 |
6.49 |
118 |
2.29 |
452 |
8.78 |
4,694 |
91.22 |
5,146 |
100.00 |
Six lanes |
5,325 |
10.84 |
2,418 |
4.92 |
7,743 |
15.76 |
41,385 |
84.24 |
49,128 |
100.00 |
Seven lanes |
190 |
7.78 |
30 |
1.23 |
220 |
9.01 |
2,221 |
90.99 |
2,441 |
100.00 |
≥ Eight lanes |
1,258 |
9.06 |
204 |
1.47 |
1,462 |
10.53 |
12,422 |
89.47 |
13,884 |
100.00 |
Unknown |
168 |
6.27 |
20 |
0.75 |
188 |
7.01 |
2,492 |
92.99 |
2,680 |
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 findings in table 28 through table 30 were not consistent across databases. FARS and GES data showed little difference between lane counts. FARS had a slightly higher percentage of SR crashes for two–lane roads, and GES had a slightly higher percentage of SR crashes for seven or more lanes (see table 28). The State data paralleled what was seen in functional class. In North Carolina, using the combined definition of SR, the multilane roads had a higher percentage of SR crashes. However, when using the over speed limit definition of SR, two–lane roads had a higher percentage of SR crashes. In Ohio, the highest percentage of SR crashes was on multilane roads.
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AADT Per Lane
Table 31. Frequency and number/percentage of SR crashes regarding AADT per lane in North Carolina.
AADT Per Lane |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
0–2,000 |
6,693 |
5.72 |
4 |
0.00 |
30,392 |
25.99 |
86,535 |
74.01 |
116,927 |
100.00 |
2,001–4,000 |
2,201 |
2.88 |
7,674 |
10.05 |
9,875 |
12.93 |
66,480 |
87.07 |
76,355 |
100.00 |
4,001–5,500 |
1,206 |
2.09 |
4,197 |
7.28 |
5,403 |
9.37 |
52,249 |
90.63 |
57,652 |
100.00 |
5,501–9,000 |
1,359 |
1.60 |
6,097 |
7.17 |
7,456 |
8.77 |
77,597 |
91.23 |
85,053 |
100.00 |
9,001–13,000 |
670 |
1.86 |
4,310 |
11.98 |
4,980 |
13.84 |
30,990 |
86.16 |
35,970 |
100.00 |
13,001–20,000 |
458 |
1.93 |
2,886 |
12.15 |
3,344 |
14.08 |
20,411 |
85.92 |
23,755 |
100.00 |
> 20,000 |
183 |
1.83 |
990 |
9.89 |
1,173 |
11.72 |
8,834 |
88.28 |
10,007 |
100.00 |
Unknown |
32 |
6.43 |
91 |
18.27 |
123 |
24.70 |
375 |
75.30 |
498 |
100.00 |
Total |
12,802 |
3.15 |
26,249 |
6.46 |
62,746 |
15.45 |
343,471 |
84.55 |
406,217 |
100.00 |
Note: n represents frequency of crashes. |
Table 32. Frequency and number/percentage of SR crashes regarding AADT per lane in Ohio.
AADT per Lane |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
0 – 2,000 |
3,861 |
5.77 |
7,445 |
11.12 |
11,306 |
16.89 |
55,616 |
83.11 |
66,922 |
100.00 |
2,001–4,000 |
6,597 |
6.37 |
4,272 |
4.13 |
10,869 |
10.50 |
92,677 |
89.50 |
103,546 |
100.00 |
4,001–5,500 |
4,365 |
5.68 |
1,964 |
2.56 |
6,329 |
8.24 |
70,506 |
91.76 |
76,835 |
100.00 |
5,501–9,000 |
6,129 |
6.35 |
3,531 |
3.66 |
9,660 |
10.01 |
86,846 |
89.99 |
96,506 |
100.00 |
9,001–13,000 |
3,851 |
8.86 |
2,356 |
5.42 |
6,207 |
14.29 |
37,241 |
85.71 |
43,448 |
100.00 |
13,001–20,000 |
4,221 |
9.94 |
1,412 |
3.32 |
5,633 |
13.26 |
36,842 |
86.74 |
42,475 |
100.00 |
> 20,000 |
1,485 |
9.50 |
229 |
1.47 |
1,714 |
10.97 |
13,915 |
89.03 |
15,629 |
100.00 |
Unknown |
168 |
6.27 |
20 |
0.75 |
188 |
7.01 |
2,492 |
92.99 |
2,680 |
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. |
Since FARS and GES do not include AADT data, this traffic density–related variable can only be examined with State data. Table 31 and table 32 show that the findings from the two States differed. In North Carolina, while using both definitions of SR, the results showed that the lower the AADT, the higher the percentage of SR crashes. This may well reflect road type because lower volume, rural roads experience higher SR percentages. In Ohio, using the combined definition of SR, the same finding as North Carolina was found; however, the over speed limit definition showed the opposite finding–a higher percentage of SR crashes was found for roads with high AADTs. This may reflect the earlier Ohio finding concerning a higher percentage of SR crashes on interstates.
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Roadway Alignment
Table 33. Frequency and number/percentage of SR crashes regarding roadway alignment.
Roadway Alignment |
FARS |
GES |
All Crashes |
SR Crashes |
All Crashes |
SR Crashes |
n |
n |
Percent |
n |
n |
Percent |
Straight |
27,286 |
6,877 |
25.20 |
4,585,418 |
886,794 |
19.34 |
Curve |
9,930 |
4,610 |
46.42 |
644,542 |
215,821 |
33.48 |
Unknown |
371 |
66 |
17.79 |
482,779 |
92,955 |
19.25 |
Total |
37,587 |
11,553 |
30.74 |
5,712,739 |
1,195,570 |
20.93 |
Note: n represents frequency of crashes. |
Table 34. Frequency and number/percentage of SR crashes regarding roadway alignment 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 |
Straight |
6,989 |
2.18 |
4 |
0.00 |
35,415 |
11.04 |
285,322 |
88.96 |
320,737 |
100.00 |
Curve |
5,705 |
9.73 |
21,081 |
35.95 |
26,786 |
45.68 |
31,852 |
54.32 |
58,638 |
100.00 |
Unknown |
108 |
0.40 |
437 |
1.63 |
545 |
2.03 |
26,297 |
97.97 |
26,842 |
100.00 |
Total |
12,802 |
3.15 |
21,522 |
5.30 |
62,746 |
15.45 |
343,471 |
84.55 |
406,217 |
100.00 |
Note: n represents frequency of crashes. |
Table 35. Frequency and number/percentage of SR crashes regarding roadway alignment 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 |
Straight |
26,270 |
6.52 |
13,717 |
3.40 |
39,987 |
9.93 |
362,903 |
90.07 |
402,890 |
100.00 |
Curve |
4,279 |
9.90 |
7,421 |
17.16 |
11,700 |
27.06 |
31,538 |
72.94 |
43,238 |
100.00 |
Unknown |
128 |
6.69 |
91 |
4.76 |
219 |
11.45 |
1,694 |
88.55 |
1,913 |
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. |
Regardless of database or definition, curves exhibit SR crash percentages that are three to four times higher than tangents. It is important to recognize that the curve percentage remains higher even using the over speed limit definition of SR.
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Roadway Profile
Table 36. Frequency and number/percentage of SR crashes regarding roadway profile.
Roadway Profile |
FARS |
GES |
All Crashes |
SR Crashes |
All Crashes |
SR Crashes |
n |
n |
Percent |
n |
n |
Percent |
Level |
26,803 |
7,734 |
28.85 |
3,044,997 |
494,713 |
16.25 |
Grade |
9,072 |
3,313 |
36.52 |
799,678 |
190,204 |
23.79 |
Hillcrest |
841 |
278 |
33.06 |
77,082 |
17,499 |
22.70 |
Sag |
112 |
49 |
43.75 |
8,874 |
3,858 |
43.48 |
Unknown |
759 |
179 |
23.58 |
1,782,109 |
489,297 |
27.46 |
Total |
37,587 |
11,553 |
30.74 |
5,712,740 |
1,195,571 |
20.93 |
Note: n represents frequency of crashes. |
Table 37. Frequency and number/percentage of SR crashes regarding roadway profile in North Carolina.
Roadway Profile |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Level |
8,421 |
3.00 |
4 |
0.00 |
39,386 |
14.03 |
241,333 |
85.97 |
280,719 |
100.00 |
Grade |
3,455 |
4.36 |
5 |
0.01 |
18,971 |
23.93 |
60,296 |
76.07 |
79,267 |
100.00 |
Hillcrest |
533 |
3.81 |
6 |
0.04 |
2,353 |
16.82 |
11,636 |
83.18 |
13,989 |
100.00 |
Sag |
285 |
5.28 |
1,206 |
22.33 |
1,491 |
27.61 |
3,909 |
72.39 |
5,400 |
100.00 |
Unknown |
108 |
0.40 |
437 |
1.63 |
545 |
2.03 |
26,297 |
97.97 |
26,842 |
100.00 |
Total |
12,802 |
3.15 |
1,658 |
0.41 |
62,746 |
15.45 |
343,471 |
84.55 |
406,217 |
100.00 |
Note: n represents frequency of crashes. |
Table 38. Frequency and number/percentage of SR crashes regarding regarding roadway in Ohio.
Roadway Profile |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Level |
23,046 |
6.67 |
12,008 |
3.47 |
35,054 |
10.14 |
310,656 |
89.86 |
345,710 |
100.00 |
Grade |
7,503 |
7.47 |
9,130 |
9.09 |
16,633 |
16.56 |
83,785 |
83.44 |
100,418 |
100.00 |
Hillcrest |
|
|
|
|
|
|
|
|
|
|
Sag |
|
|
|
|
|
|
|
|
|
|
Unknown |
128 |
6.69 |
91 |
4.76 |
219 |
11.45 |
1,694 |
88.55 |
1,913 |
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. |
Regardless of database or definition used, there was a higher percentage of SR crashes on grades than on level roadway sections as seen in table 36 through table 38. In addition, in the three databases (FARS, GES, and North Carolina) that included categories for "Sags" and "Hillcrest" (i.e., the two ways that two grades can join), sags showed an even higher percentage of SR crashes than grades. This is logical because sags are often located at the bottom of a downgrade where speeds might be highest.
Top
Work Zone
Table 39. Frequency and number/percentage of SR crashes regarding to work zone.
Work Zone |
FARS |
GES |
All Crashes |
SR Crashes |
All Crashes |
SR Crashes |
n |
n |
Percent |
n |
n |
Percent |
Construction |
721 |
214 |
29.68 |
56,367 |
14,297 |
25.36 |
Maintenance |
86 |
23 |
26.74 |
|
|
|
Utility |
16 |
3 |
18.75 |
|
|
|
Unknown work zone |
80 |
14 |
17.50 |
|
|
|
Unknown |
|
|
|
40,582 |
7,242 |
17.85 |
Yes, first harmful event related to but not in work/ construction zone |
|
|
|
5,407 |
1,493 |
27.61 |
Unknown if first harmful event in 4 or related to work/construction zone |
|
|
|
30,297 |
8,426 |
27.81 |
None |
36,684 |
11,299 |
30.80 |
5,580,085 |
1,164,113 |
20.86 |
Total |
37,587 |
11,553 |
30.74 |
5,712,738 |
1,195,571 |
20.93 |
Note: n represents frequency of crashes. Blank cells indicate that the code was not present in this database. |
Table 40. Frequency and number/percentage of SR crashes regarding work zone in North Carolina.
Work Zone |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Construction/maintenance |
|
|
|
|
|
|
|
|
|
|
Construction |
211 |
2.01 |
930 |
8.87 |
1,141 |
10.88 |
9,347 |
89.12 |
10,488 |
100.00 |
maintenance |
20 |
2.06 |
102 |
10.52 |
122 |
12.58 |
848 |
87.42 |
970 |
100.00 |
Utility |
2 |
0.73 |
11 |
4.01 |
13 |
4.74 |
261 |
95.26 |
274 |
100.00 |
Intermittent/moving |
4 |
1.38 |
19 |
6.55 |
23 |
7.93 |
267 |
92.07 |
290 |
100.00 |
Not work zone |
12,565 |
3.19 |
48,882 |
12.40 |
61,447 |
15.59 |
332,748 |
84.41 |
394,195 |
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. Blank cells indicate that the code was not present in this database. |
Table 41. Frequency and number/percentage of SR crashes regarding work zone in Ohio.
Work Zone |
Over Speed Limit |
Too Fast for Conditions |
Total SR |
Not SR |
Total |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
n |
Percent |
Construction/maintenance |
1435 |
11.71 |
355 |
2.90 |
1790 |
14.61 |
10,465 |
85.39 |
12255 |
100.00 |
Construction |
|
|
|
|
|
|
|
|
|
|
Maintenance |
|
|
|
|
|
|
|
|
|
|
Utility |
|
|
|
|
|
|
|
|
|
|
Intermittent/moving |
|
|
|
|
|
|
|
|
|
|
Not work zone |
29,242 |
6.71 |
20,874 |
4.79 |
50,116 |
11.50 |
385,670 |
88.50 |
435,786 |
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. |
There was no consistent pattern in the results in table 39 through table 41. FARS showed essentially no difference between work and nonwork zones, GES showed only a slightly higher percentage of SR crashes in the work zones (25 percent versus 21 percent), and the State findings differed from each other. North Carolina showed a lower percentage while Ohio showed a higher percentage of SR crashes for work zones under both definitions of SR.
Top
FHWA-HRT-10-024
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