Table 1.
Descriptive statistics of dependent and independent variables.
| Variable Name | Category/Explanation | Mean/Percentage | Standard Deviation |
|---|---|---|---|
| Dependent Variable | |||
| Crash severity | Severe | 33.1% | |
| Non-severe | 66.9% | ||
| Independent Variables | |||
| Environmental factors: | |||
| Speed limit | km/h | 116.1 | 11.7 |
| Number of lanes | 2.1 | 0.3 | |
| Traffic volume | 106 | 2.2 | 0.8 |
| Weekend | Yes | 30.5% | |
| No † | 69.5% | ||
| Weather | Rainy | 38.7% | |
| Cloudy | 52.1% | ||
| Sunny † | 9.2% | ||
| Location | Tunnel | 21.4% | |
| Bridge | 2.4% | ||
| Others † | 76.2% | ||
| Crash attributes: | |||
| Secondary CC | Yes | 61.2% | |
| No † | 38.8% | ||
| Truck involvement | Truck involved | 19.0% | |
| No truck involved † | 81.0% | ||
| Trailer truck involvement | Yes | 4.3% | |
| No † | 95.7% | ||
| Bus involvement | Yes | 2.1% | |
| No † | 97.9% | ||
| Crash type | Rear-end | 62.0% | |
| Rollover | 6.4% | ||
| Side-swipe | 2.7% | ||
| Hitting objects † | 28.9% | ||
| Number of vehicles involved | Single-vehicle | 42.2% | |
| Double-vehicle | 34.0% | ||
| Multi-vehicle † | 23.8% | ||
| Attributes of the primary crash in the CC series: | |||
| Crash type of the primary crash | Rear-end | 59.6% | |
| Rollover | 6.4% | ||
| Side-swipe | 0.6% | ||
| Hitting objects † | 33.4% | ||
| Number of vehicles involved in the primary crash | Single-vehicle | 52.4% | |
| Double-vehicle | 30.2% | ||
| Multi-vehicle † | 17.4% | ||
| Truck involvement in the primary crash | Yes | 20.9% | |
| No † | 79.1% | ||
| Trailer truck involvement in the primary crash | Yes | 6.1% | |
| No † | 95.9% | ||
| Bus involvement in the primary crash | Yes | 2.4% | |
| No † | 97.6% | ||
† Reference group.