scholarly journals Ballasted Track Status Evaluation Based on Apparent Track Stiffness Index

2020 ◽  
Vol 10 (14) ◽  
pp. 4729
Author(s):  
Bongsik Park ◽  
Yeong-Tae Choi ◽  
Sung Ho Hwang
Keyword(s):  
Field Tests ◽  
Stiffness Index ◽  
Evaluation Standard ◽  
Ballasted Track ◽  
Fundamental Cause ◽  
Track Stiffness ◽  
Maintenance Work ◽  
The Difference ◽  
Falling Weight ◽  
Track Status

Currently, maintenance work for ballasted track is performed based on the Track Quality Index (TQI) without a fundamental cause investigation for track irregularity. In this study, a new evaluation standard for ballasted track status is proposed to overcome the limitations of current maintenance work. The new evaluation standard is based on the stiffness index. The stiffness index is defined as the difference between the average and standard deviation of the apparent track stiffness determined by a light falling weight deflectometer (LFWD). After some field tests and analysis, it is shown that the stiffness index has a strong correlation not only with TQI but also with maintenance history. In verification results, the new evaluation standard estimated the ballasted track status quite well.

Case study: Prediction and field tests of railway noise and effects of a low-height noise barrier

2020 ◽  
Vol 68 (4) ◽  
pp. 303-314
Author(s):  
Yuna Park ◽  
Hyo-In Koh ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
...  
Keyword(s):  
High Speed ◽  
Field Tests ◽  
Residential Areas ◽  
Railway Systems ◽  
Railway Noise ◽  
Sound Levels ◽  
Noise Barrier ◽  
The Difference ◽  
Reduction Effect ◽  
The Impact

Railway noise is calculated to predict the impact of new or reconstructed railway tracks on nearby residential areas. The results are used to prepare adequate counter- measures, and the calculation results are directly related to the cost of the action plans. The calculated values were used to produce noise maps for each area of inter- est. The Schall 03 2012 is one of the most frequently used methods for the production of noise maps. The latest version was released in 2012 and uses various input para- meters associated with the latest rail vehicles and track systems in Germany. This version has not been sufficiently used in South Korea, and there is a lack of standard guidelines and a precise manual for Korean railway systems. Thus, it is not clear what input parameters will match specific local cases. This study investigates the modeling procedure for Korean railway systems and the differences between calcu- lated railway sound levels and measured values obtained using the Schall 03 2012 model. Depending on the location of sound receivers, the difference between the cal- culated and measured values was within approximately 4 dB for various train types. In the case of high-speed trains, the value was approximately 7 dB. A noise-reducing measure was also modeled. The noise reduction effect of a low-height noise barrier system was predicted and evaluated for operating railway sites within the frame- work of a national research project in Korea. The comparison of calculated and measured values showed differences within 2.5 dB.

scholarly journals A Cost-Effective Method to Reproduce the Morphology of the Nearshore and Intertidal Zone in Microtidal Environments

2020 ◽  
Vol 12 (11) ◽  
pp. 1880
Author(s):  
Stefano Furlani ◽  
Valeria Vaccher ◽  
Vanja Macovaz ◽  
Stefano Devoto
Keyword(s):  
Intertidal Zone ◽  
Field Tests ◽  
Cost Effective ◽  
Time Lapse ◽  
3D Models ◽  
The North ◽  
Cost Effective Method ◽  
Photogrammetric Method ◽  
The Difference ◽  
Sea Wall

The photogrammetric method is widely used in coastal areas and in submerged environments. Time-lapse images collected with unmanned aerial vehicles are used to reproduce the emerged areas, while images taken by divers are used to reproduce submerged ones. Conversely, 3D models of natural or human-made objects lying at the water level are severely affected by the difference in refractive index between air and seawater. For this reason, the matching of 3D models of emergent and submerged coasts has been very rarely tested and never used in Earth Sciences. The availability of a large number of time-lapse images, collected at the intertidal zone during previous snorkel surveys, encouraged us to test the merging of 3D models of emerged and submerged environments. Considering the rapid and effective nature of the aforementioned program of swim surveys, photogrammetric targets were not used during image acquisition. This forced us to test the matching of the independent models by recognizing prominent landforms along the waterline. Here we present the approach used to test the method, the instrumentation used for the field tests, and the setting of cameras fixed to a specially built aluminum support console and discuss both its advantages and its limits compared to UAVs. 3D models of sea cliffs were generated by applying structure-from-motion (SfM) photogrammetry. Horizontal time-lapse images, collected with action cameras while swimming parallel to the coastline at nearly constant velocity, were used for the tests. Subsequently, prominent coastal landforms were used to couple the independent models obtained from the emergent and submerged cliffs. The method was pilot tested in two coastal sites in the north-eastern Adriatic (part of the Mediterranean basin). The first site was a 25 m sea wall of sandstone set within a small harbor, while the second site was a 150 m route below plunging limestone cliffs. The data show that inexpensive action cameras provide a sufficient resolution to support and integrate geomorphological field surveys along rocky coastlines.

An Experience of Ageing on XLPE Insulation

2013 ◽  
Vol 64 (4) ◽  
Author(s):  
W. G. Ariastina ◽  
A. I. Weking ◽  
I. N. S. Kumara ◽  
I. A. D. Giriantari ◽  
I. N. Sugiarta
Keyword(s):  
Surface Temperature ◽  
Insulation Degradation ◽  
Maintenance Work ◽  
Conductor Temperature ◽  
Potential Losses ◽  
Distribution Feeder ◽  
The Difference ◽  
Post Insulator ◽  
Xlpe Insulation

A case study of ageing on XLPE conductor insulation of 20kV primary distribution feeder is presented in this paper. The insulation degradation mainly occurred around conductor tie where the conductor is attached to the post insulator. A section of distribution feeder with defects on the conductor insulation has been examined for this study. Potential losses due to presence of discharges have been investigated by measuring the difference current at locations of the affected conductor. Temperature measurements of the insulation surface have also been carried out. Provisional maintenance procedures were introduced to eliminate the discharges. Measurements of current and surface temperature were repeated nine months after completion of the maintenance work. Results indicated that the discharges have been completely disappeared.

scholarly journals Comparison of Real Response and Theoretical Modeling of Pavement with Thick Asphalt Layers under Heavy Traffic Load

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Jingsong Shan ◽  
Hongmei Shao ◽  
Qiuzhong Li ◽  
Peili Sun
Keyword(s):  
Theoretical Model ◽  
Heavy Traffic ◽  
Field Tests ◽  
Fatigue Cracking ◽  
Field Measurements ◽  
Traffic Load ◽  
Theoretic Model ◽  
Static Modulus ◽  
Two Samples ◽  
The Difference

Two kinds of asphalt pavement with thick asphalt layers were used to construct two samples. In structure I, a semirigid base and graded crushed stone subbase were used. In structure II, a granular base and semirigid subbase layer were used. Responses of the two structures under traffic loads were measured using optical fiber sensors, and the differences between theoretical model results and field measurements were analyzed. Field measurements show that vertical compressive stress in structure I is larger than that in structure II. The maximum tensile strain of the asphalt layer is located at the bottom of the AC-25C layer in structure I and at the bottom of the AC-25F layer in structure II. The latter is significantly larger than the former, indicating the possibility of fatigue cracking induced by traffic load is higher in structure II. The measured tensile horizontal strain at the bottom of the semirigid layer is relatively low (<30εμ) in both structure I and structure II. In theoretical model, static modulus, dynamic modulus, and interface bonding ability are considered and theoretical responses are calculated. There are significant differences between the theoretical results and field test data. In the theoretic model, the material properties of layers and bonding status of adjacent layers all influence the results. In order to reduce the difference between the calculated and measured results, numerous material tests and field tests should be carried out.

scholarly journals Estimating the Uplift Bearing Capacity of Belled Piers Adjacent to Sloping Ground by Numerical Modeling Based on Field Tests

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Yangchun Han ◽  
Jiulong Cheng ◽  
Weifeng Zheng ◽  
Shijun Ding
Keyword(s):  
Numerical Modeling ◽  
Bearing Capacity ◽  
Attenuation Coefficient ◽  
Slope Angle ◽  
Field Tests ◽  
Embedment Depth ◽  
Sloping Ground ◽  
Foundation Model ◽  
The Difference ◽  
The Impact

In order to evaluate the uplift bearing capacity of belled piers beside slopes, a series of numerical simulations are carried out based on field tests data. First, a number of uplift loading tests of full-scale belled piers are carried out on the project site of transmission line in Anhui Province, China. Second, a slope-foundation model for numerical modeling is proposed and calibrated based on field tests data. The behavior of belled piers adjacent to slopes subject to uplift load is studied by numerical modeling. The impact of three parameters, including distance (a) from the belled pier to the crest of the slope, slope angle (β), and embedment depth (h) of the belled pier, has been investigated on the uplift capacity of the belled pier. Based on the simulation results, an attenuation coefficient (ω) is put forward for evaluating the reduction of uplift bearing capacity of the belled pier. The results show that the coefficient ω is negatively correlated with distance a and depth h, and the influence of distance a is greater than that of depth h according to the results of variance analysis, but the difference is not significant by F test. Moreover, the empirical equation between attenuation coefficient ω and three key factors a, β, and h had been presented by a series of fitting.

scholarly journals Comparison between manta trawl and in situ pump filtration methods, and guidance for visual identification of microplastics in surface waters

2019 ◽  
Vol 27 (5) ◽  
pp. 5559-5571 ◽  
Author(s):  
Therese M. Karlsson ◽  
Anna Kärrman ◽  
Anna Rotander ◽  
Martin Hassellöv
Keyword(s):  
Surface Waters ◽  
Field Tests ◽  
High Volume ◽  
Expanded Polystyrene ◽  
Particle Identification ◽  
Surface Microlayer ◽  
Sea Surface Microlayer ◽  
Spatial Differences ◽  
The Difference

AbstractOwing to the development and adoption of a variety of methods for sampling and identifying microplastics, there is now data showing the presence of microplastics in surface waters from all over the world. The difference between the methods, however, hampers comparisons, and to date, most studies are qualitative rather than quantitative. In order to allow for a quantitative comparison of microplastics abundance, it is crucial to understand the differences between sampling methods. Therefore, a manta trawl and an in situ filtering pump were compared during realistic, but controlled, field tests. Identical microplastic analyses of all replicates allowed the differences between the methods with respect to (1) precision, (2) concentrations, and (3) composition to be assessed. The results show that the pump gave higher accuracy with respect to volume than the trawl. The trawl, however, sampled higher concentrations, which appeared to be due to a more efficient sampling of particles on the sea surface microlayer, such as expanded polystyrene and air-filled microspheres. The trawl also sampled a higher volume, which decreased statistical counting uncertainties. A key finding in this study was that, regardless of sampling method, it is critical that a sufficiently high volume is sampled to provide enough particles for statistical evaluation. Due to the patchiness of this type of contaminant, our data indicate that a minimum of 26 particles per sample should be recorded to allow for concentration comparisons and to avoid false null values. The necessary amount of replicates to detect temporal or spatial differences is also discussed. For compositional differences and size distributions, even higher particle counts would be necessary. Quantitative measurements and comparisons would also require an unbiased approach towards both visual and spectroscopic identification. To facilitate the development of such methods, a visual protocol that can be further developed to fit different needs is introduced and discussed. Some of the challenges encountered while using FTIR microspectroscopic particle identification are also critically discussed in relation to specific compositions found.

Field Verification of Moving Load Model for Pavement Response

1996 ◽  
Vol 1540 (1) ◽  
pp. 125-131 ◽  
Author(s):  
Raj Siddharthan ◽  
Jian Yao ◽  
Peter E. Sebaaly
Keyword(s):  
Moving Load ◽  
Field Tests ◽  
Field Testing ◽  
Material Behavior ◽  
Vehicle Speed ◽  
Strain Response ◽  
State University ◽  
Load Model ◽  
Pavement Response ◽  
The Difference

A validation study undertaken to verify the predictive capability of a recently developed moving load model to predict pavement response is described. The full-scale field-measured responses of longitudinal strain at the bottom of the asphalt concrete (AC) layer were used in the verification. The field testing program, in which the strain responses induced by a semitrailer truck were measured as a function of vehicle speed, was carried out at the Pennsylvania State University test track. The material behavior of the AC layer, which was assumed to be viscoelastic, was deduced from the laboratory behavior of the AC and from the backcalculated AC modulus from falling-weight deflectometer data. The unbound material layer properties were assumed to be elastic. The moving load model reproduced many important general observations made from the field tests, such as the existence of a complex interaction in the case of a tandem axle configuration and the strong influence of vehicle speed on the strain response. Good agreement exists between the predictions made by the model for the strain response for single and tandem axle configurations under different loading and vehicle speeds and those measured in the field. The difference is less than 14 percent, thus verifying the applicability of the moving load model to predict pavement response.

Low-cost river discharge measurements using a transparent velocity-head rod

2020 ◽  
Author(s):  
Aurélien Despax ◽  
Jérôme Le Coz ◽  
Francis Pernot ◽  
Alexis Buffet ◽  
Céline Berni
Keyword(s):  
Water Level ◽  
Low Cost ◽  
Electrical Contact ◽  
Field Tests ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Velocity Head ◽  
Low Velocity ◽  
Average Deviation ◽  
The Difference

&lt;p&gt;The common streamgauging methods (ADCP, current-meter or tracer dilution) generally require expensive equipment, with the notable exception of volumetric gaugings and floats, which are however often difficult to implement and limited to specific conditions. The following work aims at testing and validating a reliable, easy-to-deploy and low-cost gauging method, at a cost typically below 40 &amp;#8364; each.&lt;br&gt;&lt;br&gt;The &amp;#8220;velocity-head rod&amp;#8221; firstly described by Wilm and Storey (1944), made transparent by Fonstad et al. (2005) and improved by Pike et al. (2016) meets these objectives, for wading gauging with velocities greater than 20 cm/s typically. The 9.85 cm wide clear plastic rod is placed vertically across the stream to identify upstream and downstream water levels using adjustable rulers. The difference in level (or velocity head) makes it possible to calculate the average velocity over the vertical, using a semi-empirical calibration relationship.&lt;br&gt;&lt;br&gt;Experiments carried out in INRAE&amp;#8217;s hydraulic laboratory and in the field have enabled us to find a calibration relationship similar to that proposed by Pike et al. (2016) and confirm the optimal conditions of use. The average deviation to a reference discharge has been found to be close to 5&amp;#160;% except for very slow-flow conditions. The influence of the width of the rod on the velocity-head was studied in the laboratory. The uncertainty of the velocity due to the reading of water levels has been estimated. It increases at low velocity due to decreasing sensitivity, and increases at high velocities due to water level fluctuations that are difficult to average.&lt;br&gt;&lt;br&gt;Several improvements were tested in order to facilitate and improve the measurement operations, without increasing the cost too much: magnetic ruler, removal of a graduated steel rule (expensive), plastic ruler with water level and velocity graduations, reading the depth with another ruler, spirit level, electrical contact (so the operator has not to bend to the surface of the water). An operational procedure and a spreadsheet for computing discharge are proposed. The method being extremely simple and quick to apply is well suited for rapid estimates of flow (instead of floats), training or demonstrations, citizen science programs or cooperation with services with limited resources.&lt;/p&gt;&lt;p&gt;Acknowledgments&lt;strong&gt;: &lt;/strong&gt;The authors thank Q. Morice, J. Cousseau, Y. Longefay (DREAL) who were involved in this study by carrying out field tests.&lt;/p&gt;

EVALUATION OF PFWD AS POTENTIAL QUALITY CONTROL TOOL OF PAVEMENT LAYERS

2010 ◽  
Vol 16 (1) ◽  
pp. 123-129 ◽  
Author(s):  
Amir Kavussi ◽  
Shahaboddin Yasrobi
Keyword(s):  
Field Tests ◽  
Field Testing ◽  
California Bearing Ratio ◽  
Falling Weight Deflectometer ◽  
Drop Mass ◽  
Quality Control Tool ◽  
Plate Size ◽  
Weight Drop ◽  
Pavement Layers ◽  
Falling Weight

Portable Falling Weight Deflectometer (PFWD) that can be considered as simple equipment is mainly used to measure elastic moduli of pavement unbound layers. This paper evaluates the potential use of PFWD to reliably measure the elastic modulus of pavement layers. To achieve this, PFWD tests were conducted on highway sections selected from different projects in Tehran. The California Bearing Ratio (CBR) laboratory tests were also conducted on samples collected during field tests. PFWD testing parameters were varied while performing the field testing. These included drop weight, drop height, plate diameter and position of additional geophones. In addition, PFWD moduli were compared with those obtained from performing FWD testing on the same site. It was found that drop mass and loading plate size affect PFWD modulus significantly. In addition, the results indicated that good correlation exist between PFWD moduli and FWD and CBR results. Santrauka Nešiojamasis krintančio svorio deflektometras PFWD (angl. portable falling weight deflectometer) yra nesudetingas prietaisas, dažniausiai naudojamas kelio dangu nesurištu sluoksniu tamprumo moduliui nustatyti. Straipsnyje apžvelgta, kaip PFWD naudojamas kelio dangu sluoksniu tamprumo moduliams matuoti. Taikant PFWD išbandyti skirtinguose projektuose Teherane (Iranas) panaudoti kelio dangu skerspjūviai. Bandiniams papildomai atlikti Kalifornijos santykinio atsparumo rodiklio CBR (angl. California bearing ratio) nustatymo eksperimentiniai tyrimai. Atliekant lauko tyrimus naudoti skirtingi PFWD bandymu parametrai: krintantis svoris, kritimo aukštis, plokštes skersmuo ir papildomai išdestyti geofonai. PFWD nustatyti tamprumo moduliai palyginti su tamprumo moduliais, išmatuotais naudojant krintančio svorio deflektometra FWD (angl. falling weight deflectometer). Nustatyta, kad PFWD matavimu rezultatams didele itaka turi kritimo mase ir apkrovimo plokštes matmenys. Gauti eksperimentiniu tyrimu rezultatai parode, kad PFWD, FWD ir CBR matavimai gerai koreliuoja tarpusavyje.

Thermal Properties of Water-Absorbing and Surface Modified Porous Pavements

2007 ◽  
Vol 544-545 ◽  
pp. 913-916 ◽  
Author(s):  
Ree Ho Kim ◽  
Sang Ho Lee ◽  
Jung Hun Lee ◽  
Chae Sung Gee
Keyword(s):  
Surface Temperature ◽  
Field Tests ◽  
Cooling Effect ◽  
Natural Soil ◽  
Local Climate ◽  
Pavement Materials ◽  
Analysis Technique ◽  
Porous Pavement ◽  
The Difference ◽  
Surface Modified

The creation of large impervious surface in urban and urbanizing areas have led to significant impacts on local climate, which is commonly known as urban heat island (UHI). In this study, porous pavements made of recycled sludge were examined as a way to control UHI by lowering the surface temperature. A novel image analysis technique was applied to quantify cooling effect of porous pavement materials without and with water. Although the porous pavement itself has smaller heat capacity than the natural soil, supplying water to the pavement decreased its surface temperature. At its highest point, the difference in surface temperatures without and with water was more than 10 oC. The water was supplied either from the top of the pavement or from the bottom of the pavement using the capillary effects. In both cases, pavement temperature was effectively lowered. The cooling effect of pavement by surface coating using epoxy-based polymers was negligible because surface pores were blocked. Field tests also confirmed the cooling potential of porous pavements.

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