Analysis of the possibilities in railways shape assessing using GNSS mobile measurements

In recent years, a dynamic development of satellite positioning techniques using both static and mobile GNSS coordinates register mode can be observed. In addition, still developing Real-time GNSS Networks, post-processing algorithms and another measurement signal analysis algorithms, make the satellite measurements increasingly used in railway industry sector. In the article the possibilities which follows from the mobile satellite measurements in railway engineering are briefly presented. In the years 2009-2015, the authors conducted a series of field investigations on operated railway lines. The obtained results of these measurements led to the development of a number of algorithms that increase the range of applicability of GNSS measurements. The analysis of obtained results also showed how the accuracy of the measurements have increased since 2009. The achieved accuracy has been increased due to a development of GNSS positioning systems as well as improvement of the measurement methodology, i.e. configurations of satellite receivers and layouts of their placement on a mobile measuring platform. It was also found that the development of data analysis algorithms contributed to the increase in the obtained accuracy in assessment of a railway track axis shape. The authors indicate the possibilities of applying GNSS techniques at various stages of construction and operation of railways. According to the authors, the most important advantage of both the presented measurement technique and computational methodology is the ability to effectively and relatively low-cost data acquisition regarding the existing state of the railway line. These data can be successfully used to design changes to the geometry of railway lines, and therefore satellite positioning has enormous application potential in the process of modernization of operated railway lines

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

Computer-aided evaluation of the railway track geometry on the basis of satellite measurements

In recent years, all over the world there has been a period of intensive development of GNSS (Global Navigation Satellite Systems) measurement techniques and their extension for the purpose of their applications in the field of surveying and navigation. Moreover, in many countries a rising trend in the development of rail transportation systems has been noticed. In this paper, a method of railway track geometry assessment based on mobile satellite measurements is presented. The paper shows the implementation effects of satellite surveying railway geometry. The investigation process described in the paper is divided on two phases. The first phase is the GNSS mobile surveying and the analysis obtained data. The second phase is the analysis of the track geometry using the flat coordinates from the surveying. The visualization of the measured route, separation and quality assessment of the uniform geometric elements (straight sections, arcs), identification of the track polygon (main directions and intersection angles) are discussed and illustrated by the calculation example within the article

Analysis of the possibilities in railways shape assessing using GNSS mobile measurements

In recent years, a dynamic development of satellite positioning techniques using both static and mobile GNSS coordinates register mode can be observed. In addition, still developing Real-time GNSS Networks, post-processing algorithms and another measurement signal analysis algorithms, make the satellite measurements increasingly used in railway industry sector. In the article the possibilities which follows from the mobile satellite measurements in railway engineering are briefly presented. In the years 2009-2015, the authors conducted a series of field investigations on operated railway lines. The obtained results of these measurements led to the development of a number of algorithms that increase the range of applicability of GNSS measurements. The analysis of obtained results also showed how the accuracy of the measurements have increased since 2009. The achieved accuracy has been increased due to a development of GNSS positioning systems as well as improvement of the measurement methodology, i.e. configurations of satellite receivers and layouts of their placement on a mobile measuring platform. It was also found that the development of data analysis algorithms contributed to the increase in the obtained accuracy in assessment of a railway track axis shape. The authors indicate the possibilities of applying GNSS techniques at various stages of construction and operation of railways. According to the authors, the most important advantage of both the presented measurement technique and computational methodology is the ability to effectively and relatively low-cost data acquisition regarding the existing state of the railway line. These data can be successfully used to design changes to the geometry of railway lines, and therefore satellite positioning has enormous application potential in the process of modernization of operated railway lines

Accuracy assessment of mobile satellite measurements in relation to the geometrical layout of rail tracks

The paper presents the campaigns of mobile satellite measurements, carried out in 2009-2015 on the railway and tram lines. The accuracy of the measurement method has been analysed on the basis of the results obtained in both horizontal and vertical planes. The track axis deviation from the defined geometric shape has been analysed in the areas clearly defined in terms of geometry, i.e. on the straight sections and sections with constant longitudinal inclination. The values of measurement errors have been estimated on the basis of signals subjected to appropriate processes of filtration. The paper attempts to evaluate the changing possibilities of using the GNSS techniques to determine the shape of the railway track axis from 2009 to 2015. The determined average value of the measurement error now equals a few millimetres. This achievement is very promising for the prospects of mobile satellite measurements in railway engineering

Atypical application of the parametric method for track infrastructure inventory

For many years, satellite systems have seen widespread use in a variety of technical applications, as well as in operations related to setting-out and the exploitation of track infrastructure. Their main applications include an inventory of the trackage course and detecting changes in its position. In both of these tasks, the most important element that determines the quality of an analyses is the high accuracy of the determinations being carried out. Satellite surveying techniques are not always sufficiently accurate, and in such cases, it is necessary to employ other land surveying methods to process surveying data. This article presents the authors’ considerations with regards to the possibility of applying one of the most common land surveying adjustment methods, the parametric method, to operations related to an inventory of tram infrastructure in Gdańsk. The results are based on surveys carried out during a surveying campaign in the autumn of 2018. The considerations presented in the article concern a small part of the research conducted under project No. POIR.04.01.01-00-0017/17 entitled “Development of an innovative method for determining the precise trajectory of a railborne vehicle” which is being implemented by a consortium of Gdansk University of Technology and Gdynia Maritime Universit

Installation of GNSS receivers on a mobile railway platform – methodology and measurement aspects

Determining the course of a railway track axis using satellite methods relies on ensuring the precise assembly of GNSS receivers in dedicated measuring devices. Depending on the number of receivers, solutions that are based on placing the apparatus directly above the railway track axis (as well as in eccentric positions) are used to indirectly obtain data to form the basis of the desired results. This publication describes the installation of five GNSS receivers on a mobile measuring platform as part of the InnoSatTrack project. The methodology and the procedure of the geodetic measurements required to obtain the geometrical configuration of the measuring apparatus, specified in the technical project, are presented. The publication presents the principles of total station measurement methods as well as the steps taken to achieve precise results from staking out. The process of acquiring the same configuration of the GNSS receivers, based on the geometry of the squares on the two measuring platforms that were used in the research, has been shown. The final determination of the position of the receivers did not exceed an error of 0.010 m with an average error of 0.003 m, despite the occurrence of mounting difficulties. The results have demonstrated the high credibility and effectiveness of the presented solution

Analysis of positioning methods using Global Navigation Satellite Systems (GNSS) in Polish State Railways (PKP)

Each year, global navigation satellite systems (GNSS) improve their accuracy, availability, continuity, integrity, and reliability. Due to these continual improvements, the systems are increasingly used in various modes of transport, including rail transport, the subject of this publication. GNSS are used for rail passenger information, rail traffic management, and rail traffic control. These applications differ in the positioning requirements that satellite navigation systems must meet. This article presents the methods and systems of rolling stock location and tracking using the Polish State Railways (PKP) as an example. The information on the equipment used for train positioning is not specified anywhere, hence they may differ, even for the same multiple units travelling in different parts of the country. In addition, the publication presents the progress of the European Train Control System (ETCS) implementation by the PKP

Preparatory Railway Track Geometry Estimation Based on GNSS and IMU Systems

The article discusses an important issue of railway line construction and maintenance, which fundamentally is the verification of geometric parameters of the railway track. For this purpose, mobile measurements have been performed using a measuring platform with two properly arranged GNSS receivers, which made it possible to determine the base vector of the platform. The measuring functionality of the system was extended by IMU. In this article, the effect of measuring conditions on the accuracy of the results collected from GNSS receivers is analyzed. In particular, the advisability of digital filtering of the recorded coordinates to eliminate disturbances is indicated. The article also presents the possible use of GNSS devices and the IMU unit for determining the direction angle and the longitudinal and lateral inclination angles of the railway track. This makes it possible to verify the track geometry in the horizontal plane by determining the positions of straight sections, circular arcs, and transition curves. It is indicated that the results of measurements are repeatable despite the dynamic interaction between the railway track and the measuring platform. The results confirm the usefulness of the applied GNSS and IMU signal processing method for monitoring the geometrical parameters of the railway track in operating conditions