2 edition of Ballast and subgrade materials evaluation found in the catalog.
Ballast and subgrade materials evaluation
M. R. Thompson
by Dept. of Transportation, Federal Railroad Administration, Office of Research and Development, for sale by the National Technical Information Service in Washington, Springfield, Va
Written in English
|Statement||M. R. Thompson.|
|Series||Report - Federal Railroad Administration ; no. FRA/ORD-77-32, Report (National Institute of Standards and Technology (U.S.)) -- no. FRA/ORD-77-32.|
|Contributions||United States. Federal Railroad Administration. Office of Research and Development.|
|The Physical Object|
|Pagination||viii, 31 p. :|
|Number of Pages||31|
Earth materials--i.e., soil and rock--form the substructure of all railroad track. In this report, the functions and performance characteristics of each of the substructure elements (i.e., ballast, subballast, and subgrade), and the material properties that influence the substructure performance are described. The physical condition of railway ballast should be regularly inspected and accordingly, ballast cleaning should be carried out to maintain the safe operation of a track. This paper reviews current methods commonly used for evaluating the degree of ballast fouling, and due to their limitations, a new parameter — “relative ballast fouling.
Besides using the available material found online by NCARB, Funkaar institute, Amber book, etc, I am planning on buying the bundle amazon is offering which includes the Ballast ARE Review Manual and Practice Exams + ARE 5 in a Flash: Rapid Review of Key Topics by Gary E Demele. These books cover the 6 divisions and seem like a good option. The material for ballast should be of such nature that it grips the sleepers in position and prevent their horizontal movement during passage of train; It should not allow the rain water to accumulate but should be able to drain off the water immediately without percolating; It should be strong enough a resistance to abrasion; Materials for Ballast.
M. Knutson and others. Materials Evaluation Study: Ballast and Foundation Materials Research Program. U.S. Department of Transportation, Rept. FRA-ORD, Ballast and Subgrade Response to Train Loads Ernest T. Selig, Department of Civil . evaluation of granite, trap rocks, or quartzite type materials, provided the materials are defined by applicable method. For carbonate materials, dolomitic limestone is defined as having a magnesium carbonate content of 28 to 36 percent. Those carbonate materials indicating magnesium carbonate values above 36 percent shall be defined dolomite.
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Ballast and Subgrade Requirements Study: Railroad Track Substructure – Materials Evaluation and Stabilization Practices. Document Series. Technical Reports. Author. Federal Railroad Administration.
Report Number. DOT/FRA/ORD/ Office. RPD Keywords. The latest general information on the Coronavirus Disease (COVID) is available on the CDC website.
Ballast and subgrade materials evaluation. Washington: Federal Railroad Administration, Office of Research and Development ; Springfield, Va.: Available through the National Technical Information Service, (OCoLC) Material Type: Government publication, National government publication: Document Type: Book: All Authors.
undesirable level due to subgrade settlement and ballast degradation, ballast is added to raise the track. This typically does not solve the problem and after some time in service, more ballast is required.
This cyclic process of ballast dumping, surfacing, and subsequent track settlement has been the status quo in the U.S. since the 19th Size: 1MB. The overall subgrade comprised natural subgrade, the sand/rubble layer, and the imported subgrade layer.
The clayey silt used for the imported subgrade had a liquid limit of 35% and a PI of The soaked and unsoaked CBR of subgrade materials are given in Table For the imported clay subgrade, which served as the primary subgrade, a dry density of t/m 3 was obtained at OMC.
The ballast and the sub-ballast layers consist of aggregates that reduce the bearing pressures exerted by the tie to pressure values allowed on the subgrade.
The sub-ballast has the primary duties. The specification for sub-ballast materials used nowadays for the construction of federal railways was also based on the ASTM D specification and considers the curves A to D, and also curves E and F ().Comparing the requirements of the two specifications it can be seen that the differences are the following: two more curves (E and F) were included corresponding to type II materials.
Prior to placing materials, repair subgrade using sub-ballast. Place material to provide uniformity of grading throughout work.
If subgrade is dusty, sprinkle it prior to placing sub-ballast. Install sub-ballast to shape and compacted thickness shown.
Where compacted thickness is six inches or less, place sub-ballast in one layer. EVALUATION OF DESIGN OF RAILWAY'S SUB-STRUCTURE IN HIGH-SPEED formation layer and finally the track subgrade.
The sub-ballast layer has the primary function of reducing the impact of traffic loads on the track subgrade without requiring the excessive increase in thickness of the ballast. Standard granular materials of good quality are used.
ballast fouling and sub grade evaluation. Ballast fouling is a direct consequence of the ballast aging process, where fine-grained materials fill the ballast void spaces, leading to track. resistant ballast bed, well laid and compacted on a stable, compact subballast and subgrade, is the first condition for low maintenance expenditures.
Ballast must be capable of withstanding many forces. Extremely large cyclic loadings, vibrations of varying frequencies and intensities, repeated. Benefits of Moorum Ballast. Moorum is good as a sub-ballast especially in the case of weak soil subgrades.
Provides good aesthetics to the track. Drawbacks of Moorum Ballast. It is very soft and when subjected to vibrations gets converted into a powdered form and blows away. It. A precious gem of railway engineering knowledge. It presents various topics of track geotechnology - from soil properties, in-situ tests to analytical models of soils ; it covers in great detail the properties and the maintenance principles of railway ballast and subgrade.
Of particular interest to me personally was the chapter about track 5/5(2). The Subgrade shall be prepared as specified in Section and shall be approved by the Engineer before placing ballast or surfacing materials. (3)Mixing Unless otherwise specified, the Contractor may use either, or both, of the following described methods: 1.
Central Plant Mix Method – The surfacing material and water shall be mixed in an. Evaluation of modulus of subgrade reaction (Ks) in gravely results obtained the correlation between SPT results (N 1) 60 and modulus of subgrade reaction (K s) are also presented for gravely soils.
The complete data base including SPT and PLT test results and graphical correlations will be included in the main version of the paper. The horizontal variations of vertical stresses at the ballast and subgrade surfaces beneath the loaded sleeper are shown in Fig. a for the nominal case.
These stresses are highest beneath the rail seat. At the ballast-subgrade interface, the stresses are small but more uniform than at the ballast surface. 3) Interpenetration of ballast and subgrade will be eliminated by the AC. 4) Upward migration of fines will be prevented by the AC.
5) Subgrade attrition by ballast will be eliminated by the AC. 6) Water shedding will be provided by the AC. 7) Drainage of water flowing upward from the subgrade will be inhibited by the AC.
Sub-ballast is often cheaper than top ballast, so it can be used to reduce total ballast cost or to provide a filter layer between the top ballast and a fine- grained subgrade.
Determine ballast depth based on allowable subgrade stress Calculate track deflection under load and check on acceptability If deflection is unacceptable, re-do design Always consider economics. 18 Track Deflection vs.
Track Performance Source: Hay, W.W., Railroad Engineering, subgrade reaction can be improved or increased with a granular aggregate or cement-treated (or other stabilizing materials) base material (Ref’s.
10 and 11). Tables and charts for these increased subgrade reaction values using base materials can be found in a number of. The results of the laboratory tests are commonly used to reject or accept material for use as ballast and rarely imply benefits or costs of selecting alternative materials or gradations.
In this paper are presented the results of a track sampling and evaluation program to determine the performance of ballast, subballast, and the subgrade on.Keywords: Subballast, Substructure, Design, Performance and Evaluation, Field Tests, Laboratory Tests.
Abstract: Earth materials - i.e. soil and rock - form the substructure of all railroad track. In this report a summary and assessment is presented with respect to current and available.The thickness of a layer of track ballast depends on the size and spacing of the sleepers, the amount of traffic expected on the line, and various other factors.
An insufficient depth of ballast overloads the underlying subgrade or roadbase materials. In the worst .