Environmental Risk Assessment of Subway Station Construction to Achieve Sustainability Using the Intuitionistic Fuzzy Analytic Hierarchy Process and Set Pair Analysis

Table 2

Classification standard for environmental risk assessment.

Index	No.	Unit	I	II	III	IV	V
Harsh hydrological conditions	E1	—	No	Few	Moderate	Many	Excess
Adverse geological conditions	E2	—	No	Few	Moderate	Many	Excess
Adverse geomorphological conditions	E3	—	No	Few	Moderate	Many	Excess
Frequency of natural disasters	E4	times/year
Frequency of severe weather	E5	times/year
Density of underground pipelines	E6	km/km^2
Density of surrounding buildings	E7	/km^2