Intelligent Recognition of Safety Risk in Metro Engineering Construction Based on BP Neural Network

Table 3

Classification criteria for risk level S.

Grade	Valuation S	Meaning description
Level 1	0.8–1.0	The highest level of risk, which may cause devastating disasters and heavy casualties
Level 2	0.6–0.8	The level of risk is very high, causing widespread damage or casualties
Level 3	0.4–0.6	The risk level is relatively high, which may cause damage within a certain range
Level 4	0.2–0.4	The risk level is low, and appropriate preventive measures can be taken
Level 5	0–0.2	The lowest level of risk, almost no risk