Sensors for deformation monitoring of large civil infrastructures

In the maintenance of large infrastructures such as dams, bridges, railways, underground structures (tunnels, mines) and others, monitoring of deformations plays a key role in maintaining the safety serviceability conditions and for mitigating any consequences due to ageing factors and possible structural failures. [...]

Visual measurement system for wheel–rail lateral position evaluation

Railway infrastructure must meet safety requirements concerning its construction and operation. Track geometry monitoring is one of the most important activities in maintaining the steady technical conditions of rail infrastructure. Commonly, it is performed using complex measurement equipment installed on track-recording coaches. Existing low-cost inertial sensor-based measurement systems provide reliable measurements of track geometry in vertical directions. However, solutions are needed for track geometry parameter measurement in the lateral direction. In this research, the authors developed a visual measurement system for track gauge evaluation. It involves the detection of measurement points and the visual measurement of the distance between them. The accuracy of the visual measurement system was evaluated in the laboratory and showed promising results. The initial field test was performed in the Vilnius railway station yard, driving at low velocity on the straight track section. The results show that the image point selection method developed for selecting the wheel and rail points to measure distance is stable enough for TG measurement. Recommendations for the further improvement of the developed system are presented

A review on existing sensors and devices for inspecting railway infrastructure

This paper presents a review of sensors and inspection devices employed to inspect railway defects and track geometry irregularities. Inspection of rail defects is an important task in railway infrastructure management systems, and data derived from inspections can feed railway degradation prediction models. These models are utilised for predicting potential defects and implementing preventive maintenance activities. In this paper, different sensors for detecting rail defects and track irregularities are presented, and various inspection devices which utilise these sensors are investigated. In addition, the classification of the sensors and inspection devices based on their capabilities and specifications is carried out, which has not been fully addressed in previous studies. Non-Destructive Testing (NDT) sensors, cameras and accelerometers are among sensors investigated here. Correspondingly, trolleys, Condition Monitoring Systems (CMS), hi-rail vehicles and Track Recording Vehicles (TRV) are among major inspection devices that their capabilities are studied. Furthermore, the application of new devices, including smartphones and drones, in railway inspection and their potential capabilities are discussed. The review of previous and recent approaches shows that CMSs are more cost-effective and accessible than other railway inspection methods, as they can be carried out on in-service vehicles an unlimited number of times without disruption to normal train traffic. In addition, recently smartphones as a compact inspection device with a variety of sensors are employed to measure acceleration data, which can be considered as an indicator of rail track condition

Development of UAV-Based Rail Track Geometry Irregularity Monitoring and Measuring Platform Empowered by Artificial Intelligence

Rail tracks need to be consistently monitored and inspected for problems associated with rust, deformation, and cracks that, at their worst, can cause catastrophic train derailments. Many non-destructive testing approaches have been explored and extensively utilized to help inspect rails’ health, but most of them require intensive human power and/or heavy sensor systems (e.g. total stations, manual/car-mounted trolly, etc.) that are not efficient or convenient to cover a long range of rails and may interfere with the normal operation of trains.In light of the rapid development of unmanned aerial systems/vehicles (UAS’s/UAVs) and high definition photographic and optical distance measuring sensors, this paper proposes a novel UAV-based rail track irregularity monitoring and measuring platform that can remotely inspect the geometry irregularity of tracks at various angles and cover a long distance by only a few personnel. By mounting a light distance and range (LiDAR) scanning sensor and a data acquisition system on the UAV, we can continuously collect 3D point cloud data (PCD) frames that reflect the surfaces of tracks, ground, and other objects. Data points in these PCD frames are manually annotated into two classes: rail tracks and background. Then, annotated PCD frames are pre-processed and fed to train a state-of-the-art machine-learning-based 3D point cloud semantic segmentation network, RandLA-Net, to assign each point into one of the two aforementioned classes, so that point clusters that represent rail tracks can be extracted. The trained model can be deployed for real-time distinction between rails and background. Then, principal component analysis (PCA) and multiple regressions are conducted to identify the top and inner surface of the rails. In the end, various geometry measurement of rails, such as gauge, cross level, etc. can be performed to inspect any irregularities. The geometry measurement obtained by the proposed UAV-LiDAR-based framework is compared against standard official value of each geometry. The evaluation results have confirmed the similar or the more advanced performance of the proposed platform with more terrain flexibilities

Measurement and Characterization of Track Geometry Data: Literature Review and Recommendations for Processing FRA ATIP Program Data

Task Order 86From October 2018 to March 2019, the Federal Railroad Administration sponsored Transportation Technology Center, Inc. to conduct a literature review on the methods of measurement and characterization of track geometry. The goal of the review was to summarize the current state of track geometry measurement and to provide recommendations on methods for processing and characterizing track geometry data collected under FRA\u2019s Automated Track Inspection Program

Analysis of Methods Used to Diagnostics of Railway Lines

Complex diagnostics of railway lines involves techniques based on discrete and continual data acquisition. While discrete measurements belong to conventional methods, the modern continual ones use automated robotized instruments with continuous recording. Observations have become more time-efficient, but the processing epoch has become longer to evaluate a large number of data. Railway line diagnostics is realized by relative methods lead to determine relative track parameters as the track gauge, elevation, and track gradients and absolute, geodetic techniques determine directional and height ratios of the track, defined in a global coordinate and height system

Application of Least Squares with Conditional Equations Method for Railway Track Inventory Using GNSS Observations

Satellite geodetic networks are commonly used in surveying tasks, but they can also be used in mobile surveys. Mobile satellite surveys can be used for trackage inventory, diagnostics and design. The combination of modern technological solutions with the adaptation of research methods known in other fields of science offers an opportunity to acquire highly accurate solutions for railway track inventory. This article presents the effects of work carried out using a mobile surveying platform on which Global Navigation Satellite System (GNSS) receivers were mounted. The satellite observations (surveys) obtained were aligned using one of the methods known from classical land surveying. The records obtained during the surveying campaign on a 246th km railway track section were subjected to alignment. This article provides a description of the surveying campaign necessary to obtain measurement data and a theoretical description of the method employed to align observation results as well as their visualisation. Document type: Articl

Inertiamittauslaitteiston soveltaminen ratageometrian mittauksessa

Ratageometrian mittaaminen on oleellinen osa radanrakentamista ja kunnossapitoa. Radan huono kunto aiheuttaa ennen kaikkea turvallisuusriskejä henkilöliikenteelle, mutta myös esimerkiksi matkustusmukavuuden heikkenemistä ja rataan kohdistuvien kuormitusten kasvamista. Radan kuntoa mitataan nykyisillä radantarkastusmittauksilla verrattain harvoin ja radassa tapahtuvat geometriavirheet ovat omiaan entisestään lisäämään virheiden suurusluokkaa ja määrää. Lisäksi kunnossapitotyön aikana raskaan radantarkastusvaunun käyttö on hankalaa ja perinteiset takymetreilla tapahtuvat mittaukset eivät tuota jatkuvaa mittaustietoa ja ovat verrattain hitaita. Inertiamittauksella tarkoitetaan kiihtyvyyteen perustuvaa mittausta. Inertiamittauksen avulla saatava mittaustieto tuottaa jatkuvaa ja tarkepisteillä sekä GPS-mittauksella saatuun tietoon yhdistettynä myös absoluuttista mittaustietoa mitatusta rataosuudesta. Inertiamittaukseen perustuvaa paikannusta on hyödynnetty laiva- ja lentoliikenteessä jo vuosikymmenien ajan. Radanrakentamisessa tai kunnossapidossa inertiamittausta ei maailmalla vielä laajamittaisesti hyödynnetä ja tässä työssä on tarkoitus tutkia, että riittääkö inertiamittauslaitteiston tarkkuus radantarkastusmittausten tarpeisiin. Tässä työssä valittiin inertiamittauslaitteistolle kaksi eri sovellusta. Ensimmäisessä tarkastellaan, että voidaanko laitteistoa hyödyntää pienen kokonsa ja verrattain edullisen hintansa vuoksi säännöllisesti liikennöivässä kalustossa. Toinen sovellus on erityinen työnaikaisiin ja tukemistyötä edeltäviin mittauksiin tarkoitettu radantarkastuskärry. Molempien sovelluksien osalta tutkimus keskittyy laitteiston mittatarkkuuden riittävyyteen. Kärryllä tapahtuvalla inertiamittauksella voidaan parhaimmillaan riittävällä tarkepisteiden määrällä saavuttaa alle yhden millimetrin suuruinen mittavirhe. Tällöin voidaan katsoa laitteiston tarkkuuden olevan vähintäänkin riittävä radanrakentamiseen ja tuentaan liittyviin mittauksiin. Säännöllisesti liikennöivällä kalustolla mittatarkkuus ja etenkin mittausten toistettavuus koettiin kuitenkin ongelmaksi, ja menetelmä soveltuu lähinnä radan pystygeometriassa tapahtuvien äkillisten muutosten seuraamiseen, jolloin varsinaisella mittauskalustolla tehtäviä mittauksia voitaisiin tarkemmin kohdentaa alueille, joilla ongelmia esiintyy

Information Aided Navigation: A Review

The performance of inertial navigation systems is largely dependent on the stable flow of external measurements and information to guarantee continuous filter updates and bind the inertial solution drift. Platforms in different operational environments may be prevented at some point from receiving external measurements, thus exposing their navigation solution to drift. Over the years, a wide variety of works have been proposed to overcome this shortcoming, by exploiting knowledge of the system current conditions and turning it into an applicable source of information to update the navigation filter. This paper aims to provide an extensive survey of information aided navigation, broadly classified into direct, indirect, and model aiding. Each approach is described by the notable works that implemented its concept, use cases, relevant state updates, and their corresponding measurement models. By matching the appropriate constraint to a given scenario, one will be able to improve the navigation solution accuracy, compensate for the lost information, and uncover certain internal states, that would otherwise remain unobservable.Comment: 8 figures, 3 table

High cross wind gust loads on ground vehicles from moving model experiments

The environmental wind tunnel at Nottingham University has been extended so that realistic mean hourly atmospheric boundary layers can be generated at sufficient scale to allow aerodynamic tests of sharp edged vehicles to be undertaken. A moving model rig owned by British Rail Research was installed perpendicular to the flow near the end of the working section. As part of this project an automatic refiring mechanism was developed allowing some 2000 transits of vehicles incorporating an internal balance and data logger to be made across the working section with a realistic mean hourly atmospheric boundary layer present. The quality of the data from the moving model rig was assessed. Moving model rig tests and static model tests of a 1/50th scale lorry and 1/45th railway container vehicles have been conducted and extreme value forces and moments relevant to the gust time that overturn a vehicle were calculated. These are the first measurements to have been made using a realistic mean hourly ABL and modelling the vehicle's movement. This thesis assesses the usefulness of the normalised extreme force parameter in determining the extreme forces that a full scale moving vehicle experiences. It was found that the normalised extreme force parameter remains invariant with model time scale for the range of times considered. Further for both the moving model rig tests and the static tests the value of unity that this parameter takes for yaw angles above 30 degrees implies quasi steady behaviour without additional body induced unsteadiness. At lower yaw angles, however, some body induced unsteadiness is evident. These conclusions are compared with predictions from existing numerical models and previous experimental tests. The measured lift force from the static tests compared with the moving model rig tests at 90 degrees yaw angle, i. e. with the moving model stationary, shows a large difference. This is not understood and two concerns are expressed: the effect of the slot, through which the supports of the moving model travel, beneath the vehicle, may be altering the pressure in this region; or it could be due to a Reynolds number effect caused by the small underbody height above the ground