Proposing New Methods to Estimate the Safety Level in Different Parts of Freeway Interchanges

Table 6

Results of statistical analysis between means of the NCPIs estimated by the two safety estimator models versus the NCPIs achieved by field studies.

Part	Location	ANN-based model		PSO-based model		Field study		Statistical pooled t-test
		µm	σm	µm	σm	µs	σs	Sp-ANN	Sp-PSO	tANN	tPSO	t value (t-dist. table)
Waving area	Hemmat W-E: Yadegar ON and Yadegar OFF	43.34	2.23	47.9	5.90	44.88	5.53	4.22	5.72	0.93	1.35	1.711
	Hemmat Freeway W-E: Asharfi ON and Yadegar OFF	28.94	2.89	33.42	6.68	30.54	6.10	4.77	6.39	0.97	1.31	1.695
	Hakim Freeway E-W: Sheikh Bahaee ON and Chamran OFF	29.75	2.58	27.44	7.35	30.43	8.16	6.05	7.77	0.34	1.16	1.694
	Karbala Freeway E-W: Sahne ON and Hamedan OFF	21.87	1.07	19.69	2.76	21.19	2.97	2.23	2.86	1.00	1.69	1.684
	Imam Ali Freeway S-N: N-N U-turn ON and Sabalan OFF	38.02	1.08	37.31	6.64	39.28	6.99	5.00	6.82	0.78	0.89	1.692
	Imam Ali Freeway S-N: Khavaran ON and Khavaran OFF	37.38	4.74	38.8	10.67	38.03	10.46	8.12	10.57	0.23	0.21	1.695
Merge area	Hemmat Freeway W-E: Merge Asharfi N	16.3381	2.18	18.85	4.21	17.20	2.12	2.15	3.33	0.94	1.16	1.725
	Niayesh Freeway E-W: Merge Chamran S	14.7116	3.09	17.06	5.11	15.59	3.12	3.10	4.23	0.75	0.92	1.706
	Tehran-Qom Freeway N-S: Merge Vahnabad E	16.1305	4.48	14.41	5.30	15.73	4.21	4.35	4.79	0.33	0.97	1.687
	Tehran-Qom Freeway S-N: Merge Vahnabad W	15.2322	2.28	13.01	3.12	14.53	2.03	2.16	2.64	1.00	1.78	1.692
	Tehran-Saveh Freeway W-E: Merge Shahriar W	18.1533	3.41	15.17	4.22	17.24	3.07	3.25	3.69	0.85	1.68	1.694
Diverge area	Hakim Freeway W-E: Diverge Sheikh Bahaee S	1.6394	0.18	1.61	0.20	1.65	0.20	0.19	0.20	0.18	0.66	1.694
	Hemmat Freeway W-E: Diverge Yadegar S	32.335	6.01	36.52	7.30	33.83	6.76	6.39	7.03	0.60	0.98	1.711
	Tehran-Saveh Freeway E-W: Diverge Dehshade W	49.555	8.72	57.17	10.86	52.18	9.91	9.34	10.40	0.93	1.59	1.681
	Tehran-Saveh Freeway E-W: Diverge Robat Karim E	5.6069	1.83	4.23	1.44	5.39	1.83	1.83	1.65	0.32	1.86	1.706
	Yadegar Freeway N-S: Diverge Kouhestan E	89.363	14.66	99.00	17.63	92.65	16.50	15.61	17.07	0.45	0.79	1.746
Interchange ramps	Ramp: Chamran S to Hemmat W	30.45	2.62	31.65	3.90	30.88	3.80	3.26	3.85	0.47	0.73	1.676
	Ramp: Hemmat W to Chamran S	57.93	4.98	50.99	10.19	55.71	11.13	8.62	10.67	0.83	1.43	1.684
	Ramp: Imam Ali N to Mahallati W	63.02	5.42	68.99	13.11	65.10	12.37	9.55	12.74	0.62	0.86	1.697
	Ramp: Mahallati E to Imam Ali N	90.06	7.75	97.68	13.67	92.64	12.97	10.68	13.33	0.57	0.89	1.725
	Ramp: Niayesh E to Chamran S	75.77	6.52	69.17	12.32	73.65	13.11	10.35	12.72	0.63	1.09	1.689