Identification and Assessment of Subway Construction Risk: An Integration of AHP and Experts Grading Method

Table 2

Criteria for the probability grade of risk occurrence.

Level	1	2	3	4	5
The accident description	Frequent	Possible	Once in a while	Rare	Impossibility
Interval probability	P ≥ 10%	1% ≤ P < 10%	0.1% ≤ P < 1%	0.01% ≤ P < 0.1%	P < 0.01%

Note: 1: Use frequency to replace probability when the value is hard to obtain. 2: The probability for the risk occurrence should be quantified based on the specific target’s unit project, unit time, or unit length.