1 Introduction
2 Literature review
3 Data preparation
Categorical variables | Single-truck crashes | Multiple-vehicle, truck-involved crashes | |||
---|---|---|---|---|---|
Variable type | Variable/categories | Frequency | Percent | Frequency | Percent |
Crash severity |
Response
| ||||
Fatal/incapacitating injury | 35 | 3 | 108 | 7 | |
Injury/possible injury | 169 | 12 | 307 | 20 | |
Property damage only (PDO) | 1166 | 85 | 1127 | 73 | |
Crash characteristics |
Driver ejection
| ||||
Ejected | 27 | 2 | 1516 | 98 | |
No ejections | 1340 | 98 | 26 | 2 | |
Driver characteristics/factor |
Alcohol
| ||||
Alcohol involved | 3 | 0.22 | 26 | 2 | |
Alcohol not involved | 1397 | 99 | 1516 | 98 | |
Gender
| |||||
Male | 1290 | 95 | 1247 | 84 | |
Female | 75 | 5 | 234 | 16 | |
Driver conditions
| |||||
Normal | 1243 | 93 | – | – | |
Others | 100 | 7 | – | – | |
Speed compliance
| |||||
Speed was complied | 1008 | 74 | 1388 | 90 | |
Speed was not complied | 362 | 26 | 154 | 10 | |
Vehicle characteristics |
Distraction in the cabin
| ||||
Distracted cabin | 167 | 12 | – | – | |
Non-distracted cabin | 1203 | 88 | – | – | |
Environment/road |
Road condition
| ||||
Dry | 450 | 33 | 681 | 44 | |
Other (slush, ice, frost, snow, etc.) | 920 | 67 | 861 | 56 | |
Hours of crashes
| |||||
Off-peak hours | 366 | 73 | 251 | 16 | |
Peak hours | 1004 | 27 | 1291 | 84 | |
Speed characteristics |
Posted speed limit
| ||||
Speed limit greater than or equal to 65 mph | 1008 | 74 | 293 | 20 | |
Speed limit less than 65 mph | 362 | 26 | 1191 | 80 |
Categorical variables | Single-truck crashes (truck violations) | Multiple-vehicle, truck-involved crashes (all violations) | |||
---|---|---|---|---|---|
Variable type | Variable/categories | Frequency | Percent | Frequency | Percent |
Type of violations |
Response
| ||||
Speeding too fast for conditions | 297 | 2 | 1392 | 1 | |
Following too close | 288 | 2 | 1427 | 1 | |
Improper lane change | 989 | 5 | 3541 | 2 | |
Others | 18,296 | 91 | 153,010 | 86 | |
Driver characteristics/factor |
Gender
| ||||
Male | 19,243 | 97 | 117,582 | 74 | |
Female | 580 | 3 | 41,341 | 26 | |
Residency
| |||||
Resident of Wyoming | 2392 | 12 | 40,663 | 26 | |
Nonresident of Wyoming | 17,478 | 88 | 118,707 | 74 | |
Environment/road |
Hours of violation
| ||||
Off-peak hours | 4005 | 20 | 31,286 | 20 | |
Peak hours | 15,865 | 80 | 128,084 | 80 | |
Day of violation
| |||||
Week days | 7721 | 39 | 56,230 | 35 | |
Weekends | 12,149 | 61 | 103,140 | 65 |
4 Methods
5 Results
5.1 Ordinal logistics regression, crash data
Variable | Categories | Reference category | Estimates | Standard error | Wald chi-square | p value | OR |
---|---|---|---|---|---|---|---|
Single-truck crashes
| |||||||
Intercept 2 | – | – | − 2.9993 | 0.5379 | 31.0895 | < 0.0001 | |
Intercept 1 | – | – | − 0.8904 | 0.4914 | 3.2838 | 0.0700 | |
Driver condition | Non-normal driver mental condition at the time of crash | Drivers were under normal conditions | 1.2842 | 0.3581 | 12.8639 | 0.0003 | 3.612 |
Road condition | Non-dry-road condition | Dry-road condition | − 1.5563 | 0.2589 | 36.1273 | < 0.0001 | 0.211 |
Gender | Male truck driver gender | Female | − 1.1222 | 0.4364 | 6.6115 | 0.0101 | 0.326 |
Vehicle point of impact | Rollover/jackknife | Others | 1.1098 | 0.3099 | 12.8292 | 0.0003 | 3.034 |
Driver ejection | Truck driver is ejected | No ejection | 1.3752 | 0.5822 | 5.5798 | 0.0182 | 3.956 |
Truck driver distraction | Distraction exists in the cabin | No distraction in the cabin | 0.6388 | 0.3002 | 4.5270 | 0.0334 | 1.894 |
Multiple-vehicle, truck-involved crashes
| |||||||
Intercept 2 | – | – | − 2.8867 | 0.2110 | 187.2554 | < 0.0001 | |
Intercept 1 | – | – | − 1.2410 | 0.1915 | 41.9893 | < 0.0001 | |
Alcohol | Alcohol involved | Alcohol not involved | 1.2133 | 0.3837 | 9.9972 | 0.0016 | 3.365 |
Day of crash | Weekend | Weekday | 0.2565 | 0.1232 | 4.3359 | 0.0373 | 1.292 |
Hours of crash | Peak hours | Off-peak hours | 0.3787 | 0.1568 | 5.8324 | 0.0157 | 1.460 |
Gender | Female | Male | − 0.4643 | 0.1531 | 9.2005 | 0.0024 | 0.629 |
Speed compliance | Speed limit was not complied | Speed limit was complied | 0.8740 | 0.2236 | 15.2723 | < 0.0001 | 2.396 |
Speed limit | Less than 65 mph | Greater/equal than 65 mph | 0.5323 | 0.1439 | 13.6749 | 0.0002 | 1.703 |
5.2 Multinomial logistics regression, violation data
Variable | Categories | Reference category | Estimates | Standard error | Wald chi-square | p value | OR |
---|---|---|---|---|---|---|---|
Single-truck crashes, truck violations
| |||||||
Intercept 3 | – | – | − 4.3041 | 0.2176 | 391.2580 | < .0001 | |
Intercept 2 | – | – | − 4.9629 | 0.2808 | 312.4577 | < 0.0001 | |
Intercept 1 | – | – | − 3.3826 | 0.1356 | 622.2756 | < 0.0001 | |
Hours of day [off-peak vs. peak hours (reference)] | Follow too close (3) | Other violations | 0.2868 | 0.1462 | 3.8502 | 0.0497 | 1.332 |
Too fast (2) | Other violations | 0.6098 | 0.1336 | 20.8246 | < 0.0001 | 1.840 | |
Failed to keep proper lane (1) | Other violations | 0.4985 | 0.0770 | 41.9406 | < 0.0001 | 1.646 | |
Day of week [weekend vs. week days (reference)] | Follow too close (3) | Other violations | − 0.3276 | 0.1239 | 6.9940 | 0.0082 | 0.721 |
Too fast (2) | Other violations | − 0.2676 | 0.1239 | 4.6621 | 0.0308 | 0.765 | |
Failed to keep proper lane (1) | Other violations | − 0.3584 | 0.0685 | 27.3562 | < 0.0001 | 0.699 | |
Residency [not resident vs. resident of Wyoming (reference)] | Follow too close (3) | Other violations | 0.3174 | 0.2129 | 2.2214 | 0.1361 | 1.373 |
Too fast (2) | Other violations | 0.9195 | 0.2765 | 11.0559 | 0.0009 | 2.508 | |
Failed to keep proper lane (1) | Other violations | 0.6151 | 0.1334 | 21.2652 | < 0.0001 | 1.850 | |
Multiple-vehicle, truck-involved crashes, all types of violations
| |||||||
Intercept 3 | – | – | 4.4419 | 0.0750 | 3507.7364 | < 0.0001 | 4.4419 |
Intercept 2 | – | – | 4.7518 | 0.0810 | 3437.7049 | < 0.0001 | 4.7518 |
Intercept 1 | – | – | − 3.7502 | 0.0507 | 5461.0159 | < 0.0001 | − 3.7502 |
Hours of day [off-peak vs. peak hours (reference)] | Follow too close (3) | Other violations | 0.1982 | 0.0667 | 8.8321 | 0.0030 | 1.219 |
Too fast (2) | Other violations | 0.1786 | 0.0674 | 7.0224 | 0.0080 | 1.196 | |
Failed to keep proper lane (1) | Other violations | 0.6012 | 0.0394 | 232.6564 | < 0.0001 | 1.824 | |
Day of week [weekend vs. week days (reference)] | Follow too close (3) | Other violations | 0.0242 | 0.0576 | 0.1765 | 0.6744 | 0.976 |
Too fast (2) | Other violations | − 0.0286 | 0.0582 | 0.2409 | 0.6235 | 0.972 | |
Failed to keep proper lane (1) | Other violations | − 0.1837 | 0.0366 | 25.1311 | < 0.0001 | 0.832 | |
Type of vehicle [Truck vs other vehicles (reference)] | Follow too close (3) | Other violations | 0.7227 | 0.0697 | 107.4619 | < 0.0001 | 2.060 |
Too fast (2) | Other violations | 0.6989 | 0.0690 | 102.5285 | < 0.0001 | 2.012 | |
Failed to keep proper lane (1) | Other violations | 1.1102 | 0.0407 | 745.0988 | < 0.0001 | 3.035 | |
Gender [female vs. male (reference)] | Follow too close (3) | Other violations | 0.0414 | 0.0639 | 0.4192 | 0.5174 | 0.959 |
Too fast (2) | Other violations | 0.1156 | 0.0676 | 2.9242 | 0.0873 | 1.123 | |
Failed to keep proper lane (1) | Other violation | 0.1185 | 0.0444 | 7.1287 | 0.0076 | 1.126 | |
Residency [not resident vs. resident of Wyoming (reference)] | Follow too close (3) | Other violation | − 0.4855 | 0.0585 | 68.8361 | < 0.0001 | 0.615 |
Too fast (2) | Other violation | − 0.2341 | 0.0622 | 14.1890 | 0.0002 | 0.791 | |
Failed to keep proper lane (1) | Other violation | − 0.4910 | 0.0387 | 161.3121 | < 0.0001 | 0.612 |