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153 APPENDIX D Roadside Hazard Rating Category Descriptions The following is an excerpt from Prediction of the Expected May have guardrail (1.5 to 2 m [5 to 6.5 ft] from pavement Safety Performance of Rural Two-Lane Highways (67), describ- edgeline). ing the distinguishing characteristics of the 7 roadside hazard May have exposed trees, poles, or other objects (about 3 m rating categories. The final set of photos comes from the or 10 ft from pavement edgeline). FHWA IHSDM website. Marginally forgiving, but increased chance of a reportable The accident prediction algorithm uses a roadside hazard roadside collision. rating system developed by Zegeer et al. (66) to characterize the accident potential for roadside designs found on two-lane Rating = 5 roads. Roadside hazard is ranked on a seven-point categori- Clear zone between 1.5 and 3 m (5 to 10 ft) from pavement cal scale from 1 (best) to 7 (worst). The seven categories of edgeline. roadside hazard rating are defined as follows: Sideslope about 1:3. May have guardrail (0 to 1.5 m [0 to 5 ft] from pavement Rating = 1 edgeline). May have rigid obstacles or embankment within 2 to 3 m Wide clear zones greater than or equal to 9 m (30 ft) from the pavement edgeline. (6.5 to 10 ft) of pavement edgeline. Virtually nonrecoverable. Sideslope flatter than 1:4. Recoverable. Rating = 6 Clear zone less than or equal to 1.5 m (5 ft). Rating = 2 Sideslope about 1:2. Clear zone between 6 and 7.5 m (20 and 25 ft) from pave- No guardrail. ment edgeline. Exposed rigid obstacles within 0 to 2 m (0 to 6.5 ft) of the Sideslope about 1:4. pavement edgeline. Recoverable. Non-recoverable. Rating = 3 Rating = 7 Clear zone about 3 m (10 ft) from pavement edgeline. Clear zone less than or equal to 1.5 m (5 ft). Sideslope about 1:3 or 1:4. Sideslope 1:2 or steeper. Rough roadside surface. Cliff or vertical rock cut. Marginally recoverable. No guardrail. Nonrecoverable with high likelihood of severe injuries Rating = 4 from roadside collision. Clear zone between 1.5 and 3 m (5 to 10 ft) from pavement edgeline. Figures D-1 through D-7 present photographs illustrating Sideslope about 1:3 or 1:4. the seven roadside hazard rating categories.

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154 Figure D-1. Typical roadway with roadside hazard Figure D-4. Typical roadway with roadside hazard rating equal to 1. rating equal to 4. Figure D-2. Typical roadway with roadside hazard Figure D-5. Typical roadway with roadside hazard rating equal to 2. rating equal to 5. Figure D-3. Typical roadway with roadside hazard Figure D-6. Typical roadway with roadside hazard rating equal to 3. rating equal to 6.

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155 Figure D-7. Typical roadway with roadside hazard rating equal to 7.

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