Research Article
Influence of Multiple Freeway Design Features on Freight Traffic Safety
| Variable | Mean | S.D. | Min. | Max. |
| Total crashes | 5.153 | 7.472 | 0 | 49 | Truck-involved crashes | 1.765 | 3.550 | 0 | 16 | Natural logarithm of AADT (veh/day) | 11.066 | 0.666 | 9.250 | 12.453 | Section length (mile) | 0.731 | 0.931 | 0.101 | 6.972 | Number of lanes | 2.683 | 0.795 | 2 | 5 | Maximum speed limit (mph) | 64.981 | 5.843 | 50 | 70 | Horizontal curve (1 = yes, 0 = no) | 1 = 739 sites, 0 = 1402 sites | Inside shoulder rumble strips (1 = yes, 0 = no) | 1 = 1494 sites, 0 = 647 sites | Outside shoulder rumble strips (1 = yes, 0 = no) | 1 = 1534 sites, 0 = 607 sites | Lane width (ft) | 12.034 | 0.199 | 11 | 15 | Inside shoulder width (ft) | 7.718 | 3.611 | 2 | 17 | Outside shoulder width (ft) | 9.922 | 1.741 | 2 | 17 |
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