Monitoring the Stress Free Temperature of a Complex Segment of Track

2012 ◽  
Author(s):  
Harold D. Harrison ◽  
Li Cheng ◽  
Dawei Wang ◽  
Jianhua Li
Keyword(s):  
Ambient Conditions ◽  
Track Segment ◽  
Maintenance Activity ◽  
Track Maintenance ◽  
Heavy Haul ◽  
Seasonal Shifts

A 1.25 km segment of a heavy haul coal line was instrumented with Rail Stress Monitors (RSM) [1–7] and monitored throughout a winter-summer swing in ambient conditions. The track segment included a reverse curve spanning elevated, at-grade, and tunnel conditions that transitioned to a turnout. Natural events along with track maintenance activity punctuated the seasonal shifts in Stress Free Temperature (SFT).

Evaluating the impact of ballast undercutting on the roughness of track geometry over different subgrade conditions

2017 ◽  
Vol 232 (5) ◽  
pp. 1266-1276
Author(s):  
Kirk M Scanlan ◽  
Michael T Hendry ◽  
C Derek Martin
Keyword(s):  
Surface Roughness ◽  
Organic Soils ◽  
Western Canada ◽  
Railway Ballast ◽  
Track Geometry ◽  
Track Maintenance ◽  
Heavy Haul ◽  
Long Term Trends ◽  
The Impact

The progressive degradation of railway ballast is often cited as a primary factor that contributes to the development of track roughness, while ballast renewal (undercutting) attempts to manage its long-term development. Soft subgrades have been shown to strongly influence track geometry and are a contributing factor that has not been considered during conventional track maintenance. This study evaluated the impact of undercutting on long-term trends in track geometry roughness, and what impact softer subgrades had on the effectiveness of undercutting. A combined 6.90 km of Class II–IV heavy-haul track in Western Canada (undercut in 2010 and 2011) formed the basis for this analysis. Annual traffic on these sections typically totals 50 million gross tonnes. Long-term trends in the track crosslevel, alignment, and surface roughness after ballast renewal were derived from 50 track geometry surveys carried out over a five-year period (2010–2015). The results showed that undercutting significantly reduced track roughness over sand, silt, clay, or till subgrades; however, it was often ineffective when used over soft organic subgrades. Thus, while ballast degradation is the primary cause of track roughness in segments constructed on mineral subgrades, it is not a mechanism that results in track geometry roughness over soft organic soils.

Degradation of railway track geometry – Correlation between track stiffness gradient and differential settlement

2018 ◽  
Vol 234 (1) ◽  
pp. 108-119
Author(s):  
Jens CO Nielsen ◽  
Eric G Berggren ◽  
Anders Hammar ◽  
Fredrik Jansson ◽  
Rikard Bolmsvik
Keyword(s):  
Life Cycle Cost ◽  
High Growth ◽  
High Growth Rate ◽  
Railway Track ◽  
Track Geometry ◽  
Vertical Stiffness ◽  
Track Maintenance ◽  
Degradation Rates ◽  
Heavy Haul ◽  
Track Vertical Stiffness

Based on the track geometry car recordings performed from 1999 to 2016 on a section of the Swedish heavy haul line Malmbanan, the vertical track geometry degradation is analysed for wavelengths in the interval 1–25 m. The upper layer of the subgrade on parts of the rail section is peat (depths of up to 2 m), while it is moraine on others leading to a significant longitudinal variation in substructure stiffness. The degradation rates of irregularities in the longitudinal level and the influence of track maintenance (tamping) on the track geometry are studied. In parallel, a method for continuous measurement of track vertical stiffness along the line, allowing for the detection of track sections with poor support conditions, is described and demonstrated. Synchronised measurements of the longitudinal level and the track vertical stiffness are evaluated to determine whether there is a correlation between a high stiffness gradient due to variations in substructure stiffness and a high growth rate of local track geometry irregularities. It is shown that recurrent severe local track geometry irregularities often occur on track sections where there is a combination of a low magnitude and a high gradient in the substructure stiffness. In such cases, tamping may not be a cost-efficient long-term solution to the problem. Instead, upgrading of ballast and subgrade layers should be considered as an option. It is concluded that measurement of track vertical stiffness is an efficient method for the maintenance planning of a more robust railway track, which also minimises the life cycle cost and environmental footprint.

JUSTIFICATION OF RAIL FASTENING SELECTION FOR HEAVY HAUL RAILWAY OPERATION

2018 ◽  
pp. 71-86
Author(s):  
Vladimir Fedin ◽  
Alexey Bortz ◽  
Yulia Ronzhina ◽  
Yevgeniy Dudkin ◽  
Ludmila Andreeva
Keyword(s):  
Traffic Safety ◽  
Practical Importance ◽  
Weather Conditions ◽  
Transportation Safety ◽  
Dynamic Impact ◽  
Safety Control ◽  
Track Maintenance ◽  
Operation Rate ◽  
Heavy Haul ◽  
Load Increase

Objective: To improve track maintenance, which includes the reduction of damageability and life endurance improvement of ferroconcrete rail sleepers in maintenance, elimination of factors of increased dynamic impact on sub rail support, rail fastening design for heavy haul operation, which provides for traffic safety and improvement of economic performance indicators under increased mechanical loading conditions, taking into account severe weather conditions (freeze and thaw). Methods: Service damage analysis, laboratory and benchmark tests of individual track elements and in the assembled condition. Results: Operation rate and axial load increase demands improved durability of the applied track structure components under complete passenger transportation safety control. In this case economic efficiency of the applied components is a significant factor. The research results and technical solutions, having a common purpose – to improve track maintenance under the conditions of heavy haul operation were presented in the study. The measures on elimination of factors of increased dynamic impact on sub rail support were suggested in the study: 1) application of more reliable in operation bonded-bolted joints and metal-polymer bars instead of composite ones; 2) the use of higher quality rail induction welding. The improved rail fastening design was developed for rapid curves and heavy haul operation, leading to significant increase of service life of both metal parts, due to heat strengthening of the latter, and the fastening as a whole. Practical importance: The results of the conducted research make it possible to minimize the cases of destruction of ferroconcrete sleepers and solve the issues of qualitative improvement of rail fastening components.

Heavy Axle Load Revenue Service Bridge Approach Problems and Remedies

2015 ◽  
Author(s):  
Dingqing Li ◽  
Luis Maal
Keyword(s):  
Bottom Surface ◽  
Track Geometry ◽  
Track Maintenance ◽  
Entire Line ◽  
Heavy Haul ◽  
Track Stiffness ◽  
Maintenance Work ◽  
Mud Pumping ◽  
Term Performance

Two different remedies to reduce track stiffness and increase track damping for the track on the bridges were implemented for two separate ballast deck bridges with standard concrete ties located on a high tonnage heavy haul revenue service route. One remedy used concrete ties fitted with rubber pads on the bottom surface and the other used ballast mats between the ballast layer and bridge deck. The ballast sections were increased to a minimum depth of 12 inches below the bottom of the ties, and drainage improvement was made to ensure that water would not accumulate on the bridges or in the approaches. The two bridge locations were selected in September 2007 and June 2009, for remediation and long-term monitoring of performance as part of the heavy axle load revenue service mega site testing program conducted by Transportation Technology Center, Inc. and Union Pacific Railroad. Before remediation, these two locations experienced excessive track geometry degradation, mud pumping, and track component failure that required localized maintenance work on a quarterly basis (approximately 63 MGT). After remediation, no localized maintenance (except yearly surfacing operations for the entire line) has been required for more than 1,000 MGT. The main root causes of these problems were determined to be high track stiffness and low track damping for the track on the bridges, which adversely affected dynamic vehicle-track interaction when differential track settlement started to occur at the bridge approaches. Some of these ballast deck bridges with concrete ties had track modulus measured at 12,000 lb/in/in, which is considered too high to accommodate dynamic vehicle-track interaction. Long-term performance of these remedies has been excellent, resulting in significant benefits from reduction of slow orders, train delays, and major track maintenance activities.

Hydrogen bonding in liquid methanol at ambient conditions and at high pressure

2000 ◽  
Vol 98 (3) ◽  
pp. 125-134 ◽  
Author(s):  
T. Weitkamp, J. Neuefeind, H. E. Fisch
Keyword(s):  
High Pressure ◽  
Hydrogen Bonding ◽  
Ambient Conditions

Hybrid Micro-Optical Sensors via Sol-Gel Soft Lithography

2000 ◽  
Vol 628 ◽  
Author(s):  
Mark A. Clarner ◽  
Michael J. Lochhead
Keyword(s):  
Optical Sensors ◽  
Soft Lithography ◽  
Sol Gel ◽  
Silica Gels ◽  
Ph Sensing ◽  
Ambient Conditions ◽  
Sensor Applications ◽  
Patterned Structures ◽  
Biological Functionality ◽  
Indicator Dyes

ABSTRACTOrganically modified silica gels and dye-doped silica gels have been patterned into micrometer-scale structures on a substrate using micro molding in capillaries (MIMIC). This approach is from a class of elastomeric stamping and molding techniques collectively known as soft lithography. Soft lithography and sol-gel processing share attractive features in that they are relatively benign processes performed at ambient conditions, which makes both techniques compatible with a wide variety of organic molecules, molecular assemblies, and biomolecules. The combination of sol-gel and soft lithography, therefore, holds enormous promise as a tool for microfabrication of materials with optical, chemical, or biological functionality that are not readily patterned with conventional methods. This paper describes our investigation of micro-patterned organic-inorganic hybrid materials containing indicator dyes for microfluidic sensor applications. Reversible colorimetric pH sensing via entrapped reagents is demonstrated in a prototype microfluidic sensor element. Patterned structures range from one to tens of micrometers in cross-section and are up to centimeters in length. Fundamental chemical processing issues associated with mold filling, cracking and sensor stability are discussed.

Fluorescence of BODIPY Dyes in Gas Phase at near Ambient Conditions

2020 ◽  
Author(s):  
Kseniya A. Mariewskaya ◽  
Denis Larkin ◽  
Yuri Samoilichenko ◽  
Vladimir Korshun ◽  
Alex Ustinov
Keyword(s):  
Gas Phase ◽  
Molecular Interactions ◽  
Atmospheric Pressure ◽  
Fluorescence Spectra ◽  
Visible Range ◽  
Intrinsic Properties ◽  
Ambient Conditions ◽  
Ideal Model ◽  
Molecular Fluorescence ◽  
Tesla Coil

Molecular fluorescence is a phenomenon that is usually observed in condensed phase. It is strongly affected by molecular interactions. The study of fluorescence spectra in the gas phase can provide a nearly-ideal model for the evaluation of intrinsic properties of the fluorophores. Unfortunately, most conventional fluorophores are not volatile enough to allow study of their fluorescence in the gas phase. Here we report very bright gas phase fluorescence of simple BODIPY dyes that can be readily observed at atmospheric pressure using conventional fluorescence instrumentation. To our knowledge, this is the first example of visible range gas phase fluorescence at near ambient conditions. Evaporation of the dye in vacuum allowed us to demonstrate organic molecular electroluminescence in gas discharge excited by electric field produced by a Tesla coil.

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