New Role of Thermal Mapping in Winter Maintenance with Principal Components Analysis

Table 1

PCA statistical indicators for the French and UK routes.

	Case study	53 thermal fingerprints (12°C to 35°C)	8 thermal fingerprints below 5°C	4 thermal fingerprints below 5°C
French route	Weather conditions	Intermediate and extreme	Intermediate and extreme	Intermediate and extreme
	Number of principal components (PC) used	10	6	2
	Percentage of explained variance (with 1st PC)	98	99	99
	Outliers detected (number of data points)	1000	91	68
	Case study	19 thermal fingerprints (−3.4 to 6.4°C)	8 thermal fingerprints below 6.4°C	4 thermal fingerprints below 6.4°C
UK route	Weather conditions	Intermediate, extreme, and damped	5 intermediate, 1 damped, 2 extreme	2 intermediate, 1 damped, 1 extreme
	Number of principal components (PC) used	7	6	2
	Percentage of explained variance (with 1st PC)	96	96	99
	Outliers detected (number of data points)	410	74	71