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