Page 8 - Railways

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• Easy transport and installation on railway tracks. In more detail, with +/- 3mm accuracy and the installation was carried out
by the above machine with the help of workers.
• Number of simultaneous information in real time: Adjustment-tracing of railway tracks with the GRP control
system. - Final Adjustment, where now the detailed tracing was
Horizontal distance from theoretical axis (accuracy +/- 0.1 carried out with +/-0.9mm accuracy, manually and with
mm) The tracing of the railway tracks with the GRP included the appropriate tools for the micro-corrections.
all types of tracks of the project, with the following order of the
Elevation distance from theoretical axis (accuracy +/- 0.1
mm) works: - Inspection-acceptance (As Built) correspondingly, as
with the rails on the ground. Here, the identification of
Cant (accuracy +/- 0.5 mm) any theoretical—constructed track deviations was more
• Railway tracks on ground and specifically on broken stone. frequent, since it could not exceed 1 km and the concreting
Superelevation (accuracy +/- 0.5 mm)
- Rough adjustment where as initial phase the lines were of the mounting of the rails intervened with the subsequent
Track gauge (accuracy +/- 0.3 mm) micro-movements.
traced with +/- 5 mm accuracy, and a special elevation
Exact kilometre position. and rail installation machine was used, which moved along
Surveying of clearance and surrounding area. the track and compacted the broken stone. • 3.5km railway tracks on a slab inside the “Monastiraki –
- Final Adjustment, where tracing was carried out with +/- Attiki” tunnel.
Clearance check.
1.5mm accuracy, with the help of the same machine.
- The same methodology was followed here as with
- Inspection-acceptance (As Built) where measurements the foundation rails before, during the rough and final
- CONSTRUCTION PHASE of the track were made with the same density as traced, adjustment and the inspection-acceptance phases.
and essentially it was verified that it was installed exactly
• Adjustment-tracing of railway tracks with the GRP control - Their difference, as regards the methodology, with those
system. on the theoretical axis of the study. outside the tunnel, pertains to an interim stage between
rough and final adjustment. After rough adjustment, and
• Monitoring of micro-movements at the section of the
“Monastiraki-Omonoia” railway network. • Rails on slab, mounted on fixed concrete foundations. certainly before the final adjustment, it was necessary to
inspect the tunnel’s clearance in real time.
- Rough adjustment where initially the tracks were traced
Due to the small gauge of the tunnel, in width and height,
and therefore the narrow space, this was done in order
to determine with certainty and precision any interference
by any elements (supports, walls, cables, cable shelves,
electromechanical boxes, signals, signs, etc) within the
clearance that was provided for and should exist for the
correct construction of the project.

This inspection was carried out at sections of the line each
time, with the most advanced GRP 5000 control system.

Monitoring of micro-movements at the section of the
“Monastiraki-Omonoia” railway network.
The 850m-long (total length 1465 m) section of the ISAP
line between Monastiraki – Omonoia, is located inside the old
660m tunnel, which was constructed in 1893. Thus, due to
the age of the tunnel, one of the project’s objectives was to
support it, and therefore to take preventive measures during
the progress of the works inside it.
Our surveying support played an instrumental role in this
part, and pertained to monitoring the micro-movements inside
and outside the tunnel, i.e. underground and above ground.
• Underground:
Monitoring micro-movements included any convergence
presented by the tunnel walls. Before measurements started,
permanent controls had to be installed, which were targets
installed on tie rods embedded in the walls. After installation
and before the start of the works, “zero” measurements of the
controls were taken, in order to accurately observe their initial
position. Then, and simultaneously with the start of the works,
measurements were taken on a daily basis and their results
were sent directly to the construction company.

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