Abstract: To achieve real-time dynamic acquisition of bridge traffic conditions across the entire area,the Jialing River Shimen bridge in Chongqing is taken as the research object in this paper,and a research on urban bridge traffic perception method based on distributed acoustic sensing (DAS) fiber optic monitoring is carried out.A DAS fiber optic monitoring system is deployed,and the installation and layout process of distributed fiber optic cables in the bridge body is proposed.At the same time,we have assisted in arranging fiber Bragg grating (FBG) sensors to verify the DAS fiber optic monitoring results.The study demonstrates that: DAS systems can achieve high-precision dynamic perception of traffic loads across bridges,accurately capture vehicle position,trajectory,and speed information,and distinguish between heavy vehicles and sedans through vibration amplitude.DAS fiber optic monitoring senses the complete traffic situation of the bridge within a week,and overall shows the characteristics of large amplitude and high frequency of wave peaks during morning and evening peak hours and working days,which it is consistent with the actual situation.The regularity of DAS monitoring data is consistent with the FBG monitoring results,and the acceleration amplitude of the two monitoring results is basically consistent,which it verifies the effectiveness of DAS monitoring system in bridge traffic monitoring.

Key words: distributed optical fiber, bridges, monitoring, transportation