Distributed Acoustic Sensing for Monitoring Linear Infrastructures: Current Status and Trends

To develop implementation research on distributed optical fiber sensing technology, field tests were conducted on municipal roads and railways using a distributed acoustic sensor (DAS). Data were collected by the DAS during a field test for a long time period (more than 20 min), and we conducted short-term (<10 s) and long-term (≥10 s) analyses on these data separately. In the short-term data analysis, the vehicle type, vehicle length, and working status of the vehicle engine or the compressor were identified. In the long-term data analysis, the traffic flow was monitored, and the running distance, acceleration, speed, and braking distance of the vehicle were obtained. The characteristics of the vehicle operation data obtained in these field tests are important in developing the data processing method of DASs, which will help to promote the implementation of DASs.

Section: Discussionmentioning

confidence: 98%

Vehicle Operation Status Monitoring Based on Distributed Acoustic Sensor

Chen,

Ding,

Liu

et al. 2023

“…Although the systematic, safe handling of the fibres in their primary coatings on site is not feasible due to the high failure risk, they are the in-built measuring elements in other DFOS tools. These are layered cables and monolithic sensors widely used in civil engineering [ 54 , 55 ] and geotechnical [ 56 ] applications, including bridges [ 57 ], roads [ 58 ], collectors [ 59 ], pipelines [ 60 , 61 ], and many others. A brief summary of each of these two different concepts is presented in the following subsections.…”

Section: Review Of Dfos-based Toolsmentioning

confidence: 99%

Crack Shape Coefficient: Comparison between Different DFOS Tools Embedded for Crack Monitoring in Concrete

Howiacki

Sieńko

Bednarski

et al. 2023

The article presents research on the performance of different distributed fibre optic sensing (DFOS) tools, including both layered cables and monolithic composite sensors. The main need for the presented research was related to the growing applications of the DFOS techniques for the measurements of cracked concrete structures. There are no clear guidelines on the required parameters of the DFOS tools, which, despite their different designs, are offered for the same purpose (strain sensing). The state-of-the-art review and previous experiences show noticeable differences in the quality of the results depending on the applied DFOS tool. The technical construction of selected solutions was described with its theoretical consequences, and then laboratory tests on full-size reinforced concrete beams were discussed. Beams equipped with embedded tools were investigated in four-point bending tests, causing the formation of multiple cracks in the tension zone along the beams’ length. The results in the form of strain profiles registered by selected DFOS tools were analysed regarding the qualitative (crack detection) and quantitative (width estimation) crack assessment. The comparison between crack-induced strain profiles was based on a new parameter called crack shape coefficient CSC, which could be applied to assess the effectiveness of the particular DFOS tool in crack detection and analysis. It was one of the world’s first research allowing for such direct comparison between the layered and monolithic sensing tools. The summary indicates practical guidelines referring to the preferable design of the tools best suitable for crack measurements, as well as the field proofs based on data from two concrete bridges in Germany.

“…These optical sensors take advantage of optical interferometric effects to detect and quantify small vibrations in the fiber resulting from external excitation. In this way, a regular single-mode optical fiber cable of tens of kilometers becomes a dense seismic recording array of vibration sensors, which can be simultaneously interrogated at very high sampling rates [ 6 , 7 ]. Moreover, within the cables, DAS measurement can be performed by using dark (unused) fibers or by transmitting the sensing signals on different optical wavelength channels to the ones used for communications on lit (operating) fibers [ 5 , 8 ].…”

Section: Introductionmentioning

confidence: 99%

Long-Range Traffic Monitoring Based on Pulse-Compression Distributed Acoustic Sensing and Advanced Vehicle Tracking and Classification Algorithm

Corera

Piñeiro

Navallas

et al. 2023

We introduce a novel long-range traffic monitoring system for vehicle detection, tracking, and classification based on fiber-optic distributed acoustic sensing (DAS). High resolution and long range are provided by the use of an optimized setup incorporating pulse compression, which, to our knowledge, is the first time that is applied to a traffic-monitoring DAS system. The raw data acquired with this sensor feeds an automatic vehicle detection and tracking algorithm based on a novel transformed domain that can be regarded as an evolution of the Hough Transform operating with non-binary valued signals. The detection of vehicles is performed by calculating the local maxima in the transformed domain for a given time-distance processing block of the detected signal. Then, an automatic tracking algorithm, which relies on a moving window paradigm, identifies the trajectory of the vehicle. Hence, the output of the tracking stage is a set of trajectories, each of which can be regarded as a vehicle passing event from which a vehicle signature can be extracted. This signature is unique for each vehicle, allowing us to implement a machine-learning algorithm for vehicle classification purposes. The system has been experimentally tested by performing measurements using dark fiber in a telecommunication fiber cable running in a buried conduit along 40 km of a road open to traffic. Excellent results were obtained, with a general classification rate of 97.7% for detecting vehicle passing events and 99.6% and 85.7% for specific car and truck passing events, respectively.