Zbornik radova Koridor 10 - Kirilo Savić

3rd International Scientific and Professional Conference
CORRIDOR 10 - a sustainable way of integrations
the substructure, as well as requests for safe guidance and directing of the rail vehicle. Also,
superstructure design must fulfil the request for comfort for the passengers who sit or stand in the
vehicle, with minimum disturbance, and if possible, improvement of ecological relations in the
environment.
In urban environment, the influence of superstructure design on the noise and vibrations emission is of
particular importance. In addition, these structures must meet the esthetical requirements, accessibility
requirements, as well as specific conditions for construction and maintenance in urban environment.
4.1 Specificity of use of ballasted track in an urban environment
Generally, good sides of the classical superstructure solution with ballast are :
- better acoustic properties in comparison to a solution without ballast,
- developed domestic production of the majority of the structure elements,
- application of the usual technology and mechanization for construction and maintenance,
- available qualified and competent domestic staff,
- acceptable price for the meter of the track.
Bad sides of this solution are also very well known:
- inevitable change of track geometry (longitudinal level and alignment) during exploitation,
expressed as deviation from designed geometry, which leads to reduction of drive comfort and
increase of emission of noise and vibration,
- necessity of track geometry correction,
- inevitable pollution of ballast by crushing grains, sand, dust and plant seeds deposited by
wind, which requires regular vegetation control, cleaning and adding of ballast material (noisy
machine cleaning with addition of new ballast material),
- deposition of solid and liquid waste on ballast, which creates a hygienic and esthetical
problem,
- ballast creates favourable environment for rodents (especially in the tunnels) and reptiles.
Generally, correcting the stated defects requires free access of mechanization at the place of
intervention, necessary space for storage and maintenance of mechanization, as well as the space for
residence of personnel, necessary regular pauses in the timetable for rail-care and current
maintenance, alternative transport solutions in case of inevitable closure of the track, ensuring
sufficient track length where some of the corrective maintenance measures should be performed in
order to make the maintenance possible, safe, efficient and economical.
The application of mechanization in ballasted track maintenance is favourable because of its efficiency
and extremely unfavourable because of the noise. It is extremely difficult to implement the conditions
for mechanization work during the heavy traffic, insufficient work space (tracks between platforms,
high cable density, equipment and devices built into the track). The consequence is frequent inability
to apply mechanized track maintenance and to engage unreliable, long-term and inhumane manual
work.
Ballast track maintenance works become a real problem during the heavy daily traffic. The solution is
mainly sought in applying maintenance activities during the night. This often creates the problem of
insufficient time for maintenance activities when the noise level is limited during the night (according to
the national legal regulations).
Reduced emission of noise and vibration is achieved by applying elastic rail fastening systems (CEN,
2006), reducing the distance between sleepers (not over 60 cm), installation of elastic elements
beneath the concrete sleepers (under sleeper pads) and elastic mats beneath the ballast (ballast
mats) (Figure 6).
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