Table A1.
Model estimation results for truck-involved rear-end crashes (ALL).
| Variable | Fixed Parameters Model | Random Parameters Model | ||
|---|---|---|---|---|
| Coefficient | t-stat | Coefficient | t-stat | |
| Constant | 0.8045 *** | 0.0859 | 1.1960 *** | 0.0904 |
| Person Characteristics | ||||
| Male | −0.1610 *** | 0.0297 | −0.2875 *** | 0.0321 |
| • Standard deviation of parameter density function | 0.6950 *** | 0.0226 | ||
| Driver | −0.1048 *** | 0.0348 | −0.1444 *** | 0.0371 |
| Use of restraint system | −0.8249 *** | 0.0729 | −1.0177 *** | 0.0742 |
| Age under 25 | 0.1219 *** | 0.0337 | −0.1354 *** | 0.0360 |
| Vehicle Characteristics | ||||
| Truck | −1.1121 *** | 0.0486 | −1.4758 *** | 0.0549 |
| Vehicle with one or more trailing units | −0.4815 *** | 0.0736 | −0.6423 *** | 0.0805 |
| Driver drinking in vehicle | 0.4337 *** | 0.0771 | 0.5799 *** | 0.0788 |
| Roadway and Environment | ||||
| Icy or snowy road surface | −0.2256 *** | 0.0869 | −0.2395 ** | 0.0961 |
| Dark | 0.2258 *** | 0.0374 | 0.2865 *** | 0.0398 |
| Dawn or dusk | 0.2350 *** | 0.0846 | 0.2659 *** | 0.0891 |
| Crash Mechanism | ||||
| Collision order with passenger-car as leading vehicle | 0.2136 *** | 0.0349 | 0.1708 *** | 0.0379 |
| Going straight before crash | 0.1909 *** | 0.0342 | 0.1108 *** | 0.0371 |
| • Standard deviation of parameter density function | 0.7211 *** | 0.0235 | ||
| Critical event-other vehicle stopped in lane | −0.3177 *** | 0.0413 | −0.6448 *** | 0.0493 |
| • Standard deviation of parameter density function | 0.8951 *** | 0.0405 | ||
| Critical event-other vehicle in lane traveling in same direction while decelerating | −0.3147 *** | 0.0473 | −0.6994 *** | 0.0587 |
| • Standard deviation of parameter density function | 1.0258 *** | 0.0517 | ||
| Temporal Characteristics | ||||
| Summer | 0.1034 *** | 0.0318 | 0.1262 *** | 0.0344 |
| Mu(01) | 0.7886 *** | 0.0157 | 1.0179 *** | 0.0211 |
| Mu(02) | 1.5887 *** | 0.0256 | 2.0633 *** | 0.0343 |
| Number of observations | 8506 | 8506 | ||
| Restricted log likelihood | −8459.0357 | −8459.0357 | ||
| Log likelihood function | −7366.5881 | −7297.9798 | ||
| Akaike Information Criterion (AIC) | 14,769.2 | 14,640.0 | ||
Note: ***, **, * refer to Significance at 1%, 5%, 10% level.