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Federal Highway Administration Research and Technology
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This report is an archived publication and may contain dated technical, contact, and link information
Publication Number: FHWA-HRT-10-024
 Date:April 2010

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.

 

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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.

 

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FHWA-HRT-10-024

 

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