Impacts of Fog Characteristics, Forward Illumination, and Warning Beacon Intensity Distribution on Roadway Hazard Visibility

Table 1

Hazard target luminance, contrast, and RVP value for each modeled scenario, assuming an observer age of 60 years. Negative values of RVP correspond to hazard targets that could be detected but not identified; the lowest RVP values were truncated to a value of −2.0.

Forward light source intensity (cd)	Fog visibility range (m)	Warning beacon intensity (cd)	Warning beacon distribution	Position 1: target luminance (cd/m^2)	Position 1: luminance contrast	Position 1: RVP	Position 2: target luminance (cd/m^2)	Position 2: luminance contrast	Position 2: RVP
30,000	50	150	Unshielded	0.65	0.07	<−2.0	0.64	0.08	<−2.0
			Baffle	0.64	0.08	<−2.0	0.64	0.08	<−2.0
			Beam	0.63	0.09	<−2.0	0.63	0.09	<−2.0
		750	Unshielded	0.78	0.06	<−2.0	0.72	0.07	<−2.0
			Baffle	0.74	0.07	<−2.0	0.70	0.07	<−2.0
			Beam	0.64	0.08	<−2.0	0.64	0.08	<−2.0
	200	150	Unshielded	0.65	0.09	<−2.0	0.59	0.12	−0.525
			Baffle	0.64	0.09	<−2.0	0.58	0.12	−0.496
			Beam	0.50	0.12	−0.849	0.49	0.14	−0.155
		750	Unshielded	1.58	0.04	<−2.0	1.23	0.06	<−2.0
			Baffle	1.52	0.04	<−2.0	1.20	0.06	<−2.0
			Beam	0.86	0.07	<−2.0	0.73	0.10	−1.479
	600	150	Unshielded	0.53	0.32	0.689	0.44	0.39	0.717
			Baffle	0.49	0.35	0.701	0.42	0.40	0.721
			Beam	0.37	0.46	0.738	0.35	0.49	0.745
		750	Unshielded	1.36	0.13	0.328	1.01	0.17	0.509
			Baffle	1.26	0.14	0.386	0.93	0.18	0.542
			Beam	0.65	0.26	0.647	0.55	0.31	0.683
		0	Any	0.22	0.99	0.823	0.22	0.99	0.823
		150	Any	0.20	0.76	0.763	0.20	0.77	0.766
		750	Any	0.23	0.68	0.760	0.23	0.69	0.763
100,000	50	150	Unshielded	3.11	0.02	<−2.0	3.11	0.02	<−2.0
			Baffle	3.11	0.02	<−2.0	3.10	0.02	<−2.0
			Beam	3.10	0.02	<−2.0	3.09	0.02	<−2.0
		750	Unshielded	3.24	0.02	<−2.0	3.19	0.02	<−2.0
			Baffle	3.20	0.02	<−2.0	3.17	0.02	<−2.0
			Beam	3.12	0.02	<−2.0	3.10	0.02	<−2.0
	200	150	Unshielded	1.63	0.13	0.462	1.57	0.15	0.530
			Baffle	1.61	0.13	0.467	1.56	0.15	0.532
			Beam	1.48	0.15	0.512	1.47	0.16	0.559
		750	Unshielded	2.56	0.08	−0.021	2.21	0.10	0.295
			Baffle	2.49	0.09	0.027	2.18	0.11	0.307
			Beam	1.83	0.12	0.382	1.71	0.13	0.484
	600	150	Unshielded	1.27	0.46	0.861	1.19	0.50	0.866
			Baffle	1.24	0.48	0.863	1.17	0.50	0.867
			Beam	1.11	0.53	0.869	1.10	0.54	0.871
		750	Unshielded	2.11	0.28	0.818	1.76	0.34	0.838
			Baffle	2.01	0.29	0.824	1.68	0.35	0.842
			Beam	1.40	0.42	0.855	1.30	0.46	0.861
		0	Any	0.67	0.99	0.901	0.67	0.99	0.901
		150	Any	0.67	0.79	0.880	0.66	0.80	0.881
		750	Any	0.70	0.71	0.873	0.69	0.72	0.873