Before-and-After Field Investigation of the Effects on Pollutant Emissions of Replacing a Signal-Controlled Road Intersection with a Roundabout

Table 13

Logistic regression relating risk of “high” emissions to intersection type, trip direction, and test car driver.

	Number of trips with ≥ 76 mg	Number of total trips	Coefficient	Odds ratio	95% CI	value
Intersection:
Signalized	46	153		1
Roundabout	74	139	0.883	2.42	(1.44, 4.05)	0.0008
Trip direction:
Trip A	48	145		1
Trip B	72	147	0.831	2.30	(1.36, 3.87)	0.0019
Driver:
D1	52	184		1
D2	68	108	1.447	4.25	(2.50, 7.23)	<0.0001

(Likelihood ratio: χ² = 54.84, DF = 3, value < 0.0001).