Investigation of Ballast Degradation on Sebeta-Adama Railway Line
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Date
2021-11
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Railway ballast is an important part of the track support structure. Knowing the extent (condition)
and performance of the ballast is essential in the railway service in order to anticipate and
prolong ballast life, hence decreasing maintenance costs and ensuring a good ballast layer.
fouling is recorded as the main reason for ballasted track settlement and high maintenance costs
and the main reason for fouling is ballast degradation The major goal of this thesis is to assess
the level of ballast degradation on the Sebeta-Adama railway line, which is part of the EthioDjibouti
Railway
line
and
includes
the
sole
double
track
segment
with
design
speeds
of
(120
and
70)km/h
for passengers and freight trains, respectively. For this study, eight locations were
chosen based on access and the criticality of the area, all laboratory test material was collected
along railway track at 8 distinct sites (chainages) at the stations of (02+800, 17+400, 35+00,
56+300, 67+687, 70+280, 93+500, 112+800). And the evaluation was conducted using
laboratory tests such as sieve analysis, Los Angeles abrasion test, Flakiness and elongation Index,
and Fouling index, as well as design and as-built data reviewed. Ballast particles are classified as
flaky when they have a thickness (smallest dimension) of less than 0.6 of their mean sieve size, this
size is taken as the mean of the limiting sieve apertures used for determining the size fraction in
which the particle occurs. The ballast material grading is discovered within the designed range of
63-16 mm, standard sieves except at location 93+500, according to the test results. However, the
materials going through each sieve are found to be above or below the specified limit in this
range. The elongation and flakiness index of the particles also shows a considerable rise in flaky
and elongated particles, indicating there is practice breakage. The findings of the fouling index
test indicate that the ballast bed is relatively clean. According to the field inspection, the new
materials used for ballast maintenance do not match the standards, and some of the crossing
places are more susceptible to fouling from external sources. Because the line is intended for both
freight and passenger trains, freight trains had not been operating for more than a year, implying
that the loads applied to the track (ballast) were lower than the predicted operation load. Only
track geometry conditions were used to maintain the line. That is, it does not reflect the
mechanical state of the ballast or the possibility of ballast degradation. To minimize unexpected
track breakdown owing to significant ballast degradation, a proper maintenance plan and
investigation should be implemented.
Description
Keywords
Ballast Degradation Railway