GEOLOGY
The geological and geotechnical conditions along the alignment of the first 18 km of the Athens
Metro Base Project had been extensively investigated, analysed and evaluated. The results of this
survey were used as a basis in order to develop the geotechnical parameters required for the safe
design of tunnels, stations and other underground structures.
The geological substratum of the city of Athens consists of a series of geological formations known
as the system of the Athenian Schist, mainly at the depth range of the Metro works.
”Athenian Schist” is a term used to describe a sequence of originally sedimentary, flysch-like rocks
of possible Upper Cretaceous age, which have subsequently suffered metamorphosis.
The system includes clayey and calcareous sandstones, greywacke, siltstones, limestones and
shales. Igneous activity has locally introduced peridotitic and diabasic bodies causing lithologic
deformation and significant deformation of the pre-existing members.
It is possible that during the geological era of Eocene the Athenian Schist formations suffered
intense folding and thrusting. Additional factors, which affect rock mass quality, are the widespread
weathering and the alteration of the deposits.
As a consequence, the rock mass is highly heterogeneous and anisotropic not only in the
macroscopic-geotectonic scale of Attica Basin, but mainly in the mesoscopic scale of the tunnel
works. This inherent heterogeneity of the Athenian Schist rock masses gives rise to uncertainty
while correlating adjacent boreholes, something that renders the design of reliable geological
sections particularly difficult.
The quaternary formations deposited over the Athenian Schist consist of river deposits (argillaceous
and sandy materials, as well as conglomerate usually of a small thickness). In addition, large areas
are covered by diluvial deposits among the hills consisting of clay silt and sand in alternations with
breccia loosely cemented.
Finally, a surface layer with recent deposits or artificial backfillings of various thickness (1-6m)
exists in the majority of the areas along the alignment of the Project. These deposits were formed
during the historical years.
The Athenian Schist consists, in general, of rocks with a small permeability, with the
exception of rocks with a large secondary porosity (open discontinuities, karsts in
calcareous rocks, heavily fractured material of massive rocks). Thus, in general, no
large quantities of underground water, which would make more difficult the execution
of excavation works were encountered, despite the fact that based on the readings of
the piezometers the levels were only a few metres below surface.
The Metro has been designed in such a way as to address the impact of the most
adverse conditions of seismic activity recorded to date, according to the Greek Design
Standards.
Prior to the construction of the Project, geotechnical investigations were carried out in
order to obtain the appropriate information required for the design of such a Project.
The program included more than 350 boreholes which supplemented the 200
boreholes executed along the line alignment during previous surveys, i.e. one
borehole, on average, at approximately every 30m along the entire length of the
alignment. Each borehole was performed at a depth of approximately 20-30m below
surface. The execution of geotechnical surveys continued even during the construction
phase and 1100 additional boreholes have been executed in order to serve the needs
of the Base Project.
The most important geotechnical activities carried out by ATTIKO METRO
are as follows:
Survey of the geological and geotechnical conditions with 1100 boreholes, most of which
were executed with continuous soil and rock core sampling, while some of them were used
for the execution of on site tests for the optimum investigation of the conditions prevailing at
the levels where the Project is constructed, as well as for the installation of special
geotechnical monitoring instruments.
Geophysical surveys, using various techniques, such as the ground radar penetrating the soil
tracking down buried data, such as underground river channels, P.U.O. networks and
possible major archaeological finds.
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Measurement of the underground water table along the tunnel alignment in order to estimate
the general direction of the water flow, as well as any annual variations of water level for the
optimum planning of the Project.
Development of the main parameters of soil and rock strength, to be used for the design of
the Project structures. These parameters are based on results of laboratory tests of soil and
rock samples, as well as on other data collected from in situ tests.
An extended geotechnical monitoring program before, during and after the execution of
excavation works is executed for the safety of the overlaying and/or adjacent buildings and
structures, as well as for the verification of the assumptions regarding the Project planning.
CONSTRUCTION METHODS
The entire ATHENS METRO project is underground. In this way, its objective, i.e. the rapid transfer
of citizens in the wider area of the capital is achieved. For the construction of the underground
Metro stations and tunnels, up-to-date methods, which ensured safe, workmanlike and rapid
completion of the project, were applied. The project construction methods were used either
separately or combined one to another, as deemed applicable, always in relation with the
geological conditions and the in situ conditions of the surrounding area.
Excavation with the use of Tunnel Boring Machine (TBM). This method was applied for
the boring of tunnels; in particular TBM1 (named IASSONAS) was used in Line 2 section from
LARISSA Station to AGHIOS IOANNIS Station, while TBM2 (named PERSEFONI) was used in
Line 3 section from KATEHAKI Station to SYNTAGMA Station.
Excavation with the use of the Open Face Shield (OFS). This method was used for tunnel
boring and specifically for the construction of DAFNI – AGHIOS DIMITRIOS tunnel section of
the Base Project, 765m. long, as well as for ANTHOUPOLI – PERISTERI Line 2 section, 910m.
long.
Excavation with the use of Earth Pressure Balance machine. This method was applied for
tunnel boring and namely for the construction of the tunnel section from DOUKISSIS
PLAKENTIAS to XANTHOU Shaft, 3,374m total long, of Line 3 extension to Doukissis
Plakentias, while ths machine is now “working” for the construction of the extension of Line 2
to Elliniko.
Use of the New Austrian Tunnelling Method (NATM). It was used for tunnel boring, at
soils with poor mechanical characteristics, as well as for the excavation of some stations of
the Project, namely PANEPISTIMIO, AKROPOLI, AMBELOKIPI, MONASTIRAKI, OMONIA, as
well as for the excavation of the deepest section of SYNTAGMA Station. Moreover, the
method was used at large parts of the network extensions to Doukissis Plakentias, to Aghios
Dimitrios, to Aghios Antonios, to Egaleo, etc.
Use of the Cut and Cover method. This method was mainly used for the excavation of the
stations of the Project, as well as in a few cases, for the excavation of tunnels at locations
where problems were encountered due to poor mechanical characteristics of the soil. Many
sections of the Athens Metro network were constructed using this method, such as the
Stations: SEPOLIA, ATTIKI, LARISSA, METAXOURGHIO, SYNGROU-FIX, N. KOSMOS, AGHIOS
IOANNIS, DAFNI of Line 2, as well as ETHNIKI AMYNA, KATEHAKI, PANORMOU, MEGARO
MOUSSIKIS, EVANGELISMOS, SYNTAGMA (Line 2 Station which is located at a smaller
depth). This method was also used for ATTIKI-LARISSA and KATEHAKI-ETHNIKI AMYNA
tunnel sections. The said method was also used for several sections of the extensions, such
as AGHIOS DIMITRIOS & AGHIOS ANTONIOS along Line 2, HALANDRI & DOUKISSIS
PLAKENTIAS Stations along Line 3, as well as a section of DAFNI – AGHIOS DIMITRIOS
tunnel.
Use of the Cover and Cut method. This method constitutes a variation of the cut & cover
method and was used only at SYNTAGMA Station of Line 2, due to the particularity of the
area.
Underground Conventional Boring Method (
)
The underground tunnel boring method using conventional means (known as NATM method
or New Austrian Tunneling Method) is the second (in terms of preference) construction
method applied internationally for the construction of tunnels using the underground boring
method. The Tunnel Boring Machine (
) is the method, which is preferably used for the
construction of tunnels.
In urban areas where Metropolitan Railways (Metro) are constructed, it is important not to
disturb the functions of the city even if this implies increase in the financial cost of the
projects. Using the underground construction methods for stations and tunnels, the
occupation of areas at the surface (squares, streets, private plots, etc), the relocations of
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PUO pipes (water, power, telephone supply, etc) traffic diversions and archaeological
excavations are avoided.
As to the Athens Metro, the NATM method was widely used both for the construction of
tunnel sections and some of the Stations at the center of Athens. In particular, it was used
for the construction of PANEPISTIMIO, AKROPOLI, AMBELOKIPI, MONASTIRAKI, OMONIA
and SYNTAGMA Stations. Moreover, the said method was applied at large sections of the
network extensions to Doukissis Plakentias, Aghios Dimitrios, Aghios Antonios and Egaleo.
Construction Mehodology
The basic principle of this method is to maintain the strength of the environment at the
surface surrounding the tunnel and fully utilize it. Controllable soil deformation with the use
of flexible retaining – contrary to previous views concerning “heavy” retaining-has positive
effect and has as a result the safe development of the soil strength. The methodology of the
project design/construction is the following:
Geotechnical/geological investigations and tests are executed (on site and
laboratory) for the identification of soil characteristics in the area where the tunnel
has been planned to be bored.
The design (calculations and drawings) of the excavation and the temporary
retaining of the tunnel is under way based on the geotechnical characteristics of the
soil, which resulted during the previous phase. Moreover, the design of the
permanent (final) lining of the tunnel is prepared.
The excavation is executed using conventional mechanical means (road header,
conventional excavator, etc) and sometimes the excavation front is directly retained
at several phases, depending of the quality of the soil.
Upon completion of the excavation, which is gradually performed depending on the
characteristics of the rocks and the project, there follows a system of temporary
retaining consisting of shotcrete lining (gunite), rockbolts, steel frames etc. In case
of soil with poor characteristics, prior to the excavation, forepoling beams are
installed in the entire area over the tunnel vault in the form of an umbrella providing
protection to the excavation front. Frequently, excavation is performed in two
phases, the upper semi-section (vault) and the lower semi-section (invert).
Depending on the subsoil and the geometry of the tunnel the
excavation can be performed in more than one phases. The time of
installation of the initial retaining, as well as the completion of the
full ring of the lining are important for the monitoring of
deformations. The system of direct support, along with the soil
surrounding the tunnel constitute the bearing structure of the
tunnel at this phase. Ground water can be often encountered at the
Athenian subsoil; in this case, systematic pumping is performed
during the construction.
Throughout the construction, the behavior of the subsoil and the
temporary retaining are monitored on a systematic basis, i.e. the
settlements at the soil surface and the adjacent buildings any
convergence within the tunnel, the increase/decrease of ground
water level, etc are measured. Safety of the buildings located
adjacent to or over the alignment of the tunnel is a particularly
crucial issue and it is addressed via continuous monitoring by means
of the appropriate instruments and on site visits by ATTIKO METRO
engineers. The results of the measurements are compared with the
assumptions and the results of the design and, if needed, the
necessary modifications to the support system and the time
sequence of works are made. In addition, these data are used for the identification
and/or the checking of the assumptions of the design of the permanent lining of the
tunnel, which will subsequently follow.
The final (permanent) lining of the tunnel is constructed when the system of the
initial support has reached conditions of balance. The permanent lining provides
increased safety as to the project lifetime creates a unified interior surface and
improves its water tightness. The permanent tunnel lining is made of in situ cast
reinforced concrete. Special segment metal forms, usually self-supporting ones, are
used, thus significantly reducing the time and the cost of the project. There are
hydraulic levers, which can adjust the desirable thickness of the lining. The overall
length of such moulds is in the order of 10-12m. depending on the section. Firstly,
the lower part of the tunnel (invert) is constructed and special water stops are placed
at the construction joints for waterproofing. At a later stage the vault is concreted
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with the use of self-supporting segment metal forms. Upon completion of injection, it
takes some hours to remove the metal forms. In view of achieving adequate
concrete strength rather shortly, its mix is enriched with chemical admixtures. Given
that there is a small void between the crown of the concrete and the soil at the
tunnel top, there follows cement grout injection for filling the voids.
Water tightness
In the Technical Specifications of the Project, the required degrees of water tightness for the
various parts of the Metro structures are specified. In the Base Project, the stations were
specified to be fully watertight, while at the tunnels the existence of restricted areas of
humidity at the points of the construction joints was acceptable.
The basis for the sufficient waterproofing of the underground projects is always the design
and workmanlike construction. Special attention should be paid to the concrete mix, the
compaction and maintenance after the laying procedure as well as the adequate coverage of
the reinforcement. As to the Metro tunnels, it was not required to place a waterproofing
membrane, while the limited water penetration was acceptable. At the new Metro extensions,
the specifications were even stricter and it is required to place a waterproofing system even
at the tunnels of the Project.
At the Metro stations, any penetration and surface damp patches are not acceptable since
these locations house passengers or personnel rooms,
machinery and electrical installations areas, architectural
finishes etc. In order to ensure the above, water tightness
systems are used with materials and work of appropriate
quality. Waterproofing membranes are usually made of PVC
or polyethylene and are placed between the temporary and
the final lining of the tunnel, protected with geotextile. The
parts of the membranes are welded in an appropriate
manner, while at the locations of the construction joints
(concreting interruption or joint displacement) water stops
are placed. All materials are subject to tests placed on site
the project and adhere to German specifications DS 853 and DIN 16726.
Cut & Cover Mehod
Despite the fact that the underground tunnel boring methods, either using the TBM or
conventional mechanical means (NATM), are preferably used in central areas of the city, as
we move away from the said areas we turn to the cut & cover method for the construction of
both tunnels and Metro stations. This method is also used in case there is available area even
if we are in the city centre. This happens because the cut & cover method is cost effective
and more simple, safe and easy to control in its implementation. The disadvantages of the
method as regards its implementation are as follows: a) all PUO pipes located in the area
where excavation works are to be executed should be removed, b) an archaeological
investigation should precede in order to identify any antiquities – which is very important for
Athens, and c) all required traffic diversions should be effected. These interventions are time
consuming, increase the cost, while at the same time the archaeological investigations
involve great uncertainty as to the duration and their final cost.
Although the method is simply called “open cut”, in fact it is a “cut & cover” method, since
the structures upon their completion are backfilled and they finally become underground, as
the case is when construction is made using the underground boring method is used.
Construction methology
The methodology of the cut & cover is simple in terms of conception. At first, the trench is
excavated and its slopes are appropriately retained – as to the Metro works, the slopes are
always vertical. Then, the permanent bearing structure of the station or the tunnel “is built”,
starting from the foundation upwards, i.e. as this is the case for an ordinary structure.
Finally, the structure is backfilled up to the surface of the soil and the area is reinstated. In
particular, the phases are as follows:
A geotechnical/geological investigation and tests (on site and laboratory ones) are
executed in view of identifying the soil characteristics in the area where our structure
is to be constructed.
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A design is prepared (calculations and drawings) related to the excavation and the
temporary retaining, based on the geotechnical characteristics of the soil which
resulted from the previous stage. Moreover, the design of the permanent bearing
structure is carried out.
Prior to the commencement of the main works, the required archaeological
excavations are carried out, all the PUO pipes (related to water supply, power supply,
telephone connection etc.) and the eventual traffic diversions are executed.
The temporary retaining of the excavation usually consists of circular concreting
piles, whose diameter is in the order of 0, 80 – 1, 00 m., spaced at 1,50,-2,50m
along the perimeter of the anticipated excavation prior to its commencement. The
pile row is connected at its pile cap by means of a strong concreting beam. The
excavation is carried out using conventional mechanical means (excavators,
hammers etc.) up to a fixed depth, e.g. 3,5m and then anchors are placed at holes,
which are drilled at the soil through piles. These anchors are long
enough (in the order of 15-25m) and they are prestressed using the
force provided for by the design. Then a wire mesh is applied along
the perimeter of the trench and a shotcrete is placed. Subsequently,
the excavation continues up to the next level and another series of
anchors is placed and prestressed. This cycle continues up to the
final level of the excavation, where the structure will be founded. If
there is ground water at the surface of the trench, then the said
water is discharged through systematic holes/piping at a depth of 34m. on the retaining structure/excavation and they are pumped
using the appropriate drainage system.
The water proofing system of the structure, as the case is for the
entire new Metro network, is placed at the invert and the peripheral
surfaces at the perimeter of the trench and it consists of geotextile,
waterproofing membrane and water stops.
The construction of the bearing structure is carried out in phases
starting from the foundation, and then follow the walls, the roof slab
in case of a tunnel. As to the stations, the construction of
intermediate flat slabs and walls. The construction commences with
the installation of the steel reinforcement of the foundation slab (or
general lean concrete slab), as provided for by the
design. Subsequently, class C25/30 concrete is
injected, in phases along the entire length of the
construction with the provision of appropriate
joints. The construction of the remaining elements
of the permanent structure is made in a similar
way.
With regard to the retaining works, it is clarified that the
retaining of the excavations at the Athens Metro was
executed exclusively with the use of drilling piles made of reinforced concrete (shaft piles)
and prestressed anchors. At the first sections, the “Berlin method” was used; based on this
method steel piles are placed up to a depth retained squarely with the use of steel struts,
while at layers of the subsoil which are at a greater depth, a lighter retaining is used with
reinforced shotcrete and passive ground bolts. This methodology was used at Larissa Station
and at a large section of Attiki – Larissa tunnel section.
Cover & Cut Method
The Cover & Cut method (or “ top-down” method) is a variation of the cut & cover method.
The phases of this construction methods are as follows:
the vertical retaining panels (piles, diaphragm walls, etc.) along the perimeter of
the excavation to follow are constructed from the surface,
an excavation is initially carried out up to the level of the roof slab of the
structure. Depending on the excavation depth, a light retaining of the slopes
may be needed,
the roof slab on the excavation bottom is concreted. The slab is connected with
the perimeter retaining and it is supported on it,
backfilling works are carried out over the slab and the surface of the soil is
reinstated,
the excavation works for the station or the tunnel commence underneath the roof
slab by means of the ramp which has been left at a certain point. The excavation
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is executed in phases, while the required retaining elements (e.g. anchors, struts)
are installed gradually.
upon completion of the excavation of the entire trench, works related to the
construction of permanent bearing structure elements commence. These elements
usually consist in the raft (foundation slab) and the lateral walls, while in case of a
station it is also the construction of intermediate floor slabs. In case diaphragm walls
are used as a lateral retaining means, other permanent walls are not constructed,
since the same diaphragm wall act as a final perimeter structure.
The advantages of this method consist in the reduced time of extended worksite occupations
and the rate of reinstatement and release of the area for use (vehicular circulation, squares
etc) for use and finally the mitigation of disturbance as to the functions of the city. Its
disadvantages are the increased cost and the more complicated construction procedure.
As to the Athens Metro, this method was used only for SYNTAGMA Station (of Line 2) due to
the particularity of the area. The design provided for the construction of steel piles along the
perimeter of the station and the concreting of the roof slab in Amalias Avenue in two phases,
in terms of the road pavement width and then the construction of the station in phases as
described above. During the construction of the bearing structure of the
station, the external walls were constructed from down to top. In their
interior, the steel piles were integrated, thus being part of the
permanent walls of the Station.
TUNNEL BORING MACHINES
(Tunnel Boring Machine)
The TBM Hard rock shield was designed by
Mitsubishi
Japan
constructed
by
Company
NEYRPIC
and
was
FRAMATOME
MECHANIQUE (NFM) FRANCE.
The length of the TBM, including back-up
Gantries and California switch, is 150m.
The overall weight is 1,650 tones.
TBM works consist in the production of
850,000 m3 excavated material & 350,000
m3 of concrete. The TBM works with a
four-shift
system,
engaged
in
35
surface
men
and
per
shift
underground
activities, seven days per week. The TBM
crew consisted of 21 men. The TBM 1 is
named
“IASON”
and
the
TBM
2
“PERSEFONI”.
The TBM can be divided into two sections:
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The TBM Cutter head (Shield).
th
The Back - up Gantries. The first excavation by TBM1 started on April 25 , 1994 from
Larissa station. The first Breakthrough at Deligianni Station took place on May 13th,
1995.
The rates of the TBM have been 4.5 to 17 m / working day or approx. 3 to 12 rings/working
day. Individual daily rates, not considering stoppages for breakdown, etc. ranged from 19.5
to 24 m / working day or about 13 to 16 rings / working day. A typical cycle for 1.5m
advance of TBM requires 25 min. for excavation, 30 min. for ring erection and 5 min. for
cleaning and preparation. The TBM cutter head, the
revolving part, excavates (9516mm diameter) the hard and
soft ground tunnel with a variable rotational speed of the
cutter head from 0 to 4 rpm and rated torque from 1140 to
1368 tons - m. The length of the Cutter Head is 1500 mm.
The cutter head has 63 pieces of hard disks, 17” inch
diameter, placed at individual radius & 200 pieces of drag
bits.
The disc cutters and drag bits can be replaced from the rear
side of the cutter head. The two over cutters, mounted at
the periphery of the cutter head, created an over cut of
60mm, thus allowing a better steering of the shield and
reducing the TBM friction forces.
The cutter head rotates in both directions, clockwise and anti-clockwise, by 16 hydraulic
motors (180kw) reducing gears with maximum output speed 57.6 rpm and maximum
working pressure 350 bars. The propulsion of the TBM is electric-hydraulic.
The front shield has an outer diameter of 9456 mm and the rear shield an outer diameter of
9440 mm. The overall length of the front and rear shield is 7515 mm. The shield weights 880
tones. The skin of the rear shield is 92 mm thick.
The front and rear shields are articulated one to the other. The two parts of the shields are
connected by 16 articulation jacks, 360 mm diameter, 260 bar, which make it possible to
orient one body in relation to the other in all spatial directions.
The total stroke of the articulation cylinders is 500 mm and allows for retraction of the front
shield plus cutter head up to 300 mm, thus creating access to the face. Minimum tunnel
curve radius of the profile is 300m & compensation curve radius is 250m.
The amount of the excavated material for a complete stroke of 1.5m advance was
approximately 192m3. The excavated material passes into the cutter head chamber through
openings (32% of the cutter head face is open to the ground) of the cutter head periphery.
Then, picked up by the cutter head blades while the top part is lifted up, it falls into the
hopper. The cutter head hopper empties the excavated muck onto a conveyor belt (primary
conveyor) located at the level of the tunnel axis.
The primary conveyor is 18.25 m long and 1.2 m wide. The muck is dropped from the
primary conveyor onto the secondary belt conveyor, 28.80 m long, and then to the third
conveyor belt, 38.00 m long, located on the structures of the back-up gantries.
Then, the third conveyor pours the muck into a 30m-long shuttle conveyor that moves
parallel to the tunnel axis for filling the mucking cars without moving them.
During TBM operation, all excavated material is collected into the muck skips by the conveyor
belts. The conveyor belts are designed for a capacity of 950 t/h or 750 m3/h.
If water appears on the ground, the primary conveyor belt is retracted and a safety gate
isolates the cutter head chamber from the interior area of the shield. An emergency pump
140 kW is installed in front of the hopper to evacuate the water from the cutter chamber via
tube extension device.
The flow rate is 82 lt./s and 60 m of water pressure. The max. inflow of ground water
encountered during excavation was 120 lt. / min.
The TBM moves forward by pushing against the last prefabricated segmental tunnel concrete
ring with the 28 hydraulic thrust jacks (320 mm diameter) and with a 5600 tones (260 bar
each jack) force.
The resulting force on the ground face was up to 3000 tones or 42 tones/m2. The maximum
extended stroke of the pushing jacks is 2300 mm allowing sufficient space for ring erection
within the rear shield.
The front shield of the TBM is fitted with 6 radial jacks (front grippers) with conical shape
(250mm diameter, 350 bar) and extended stroke up to 150 mm. The front grippers are
preventing the TBM from rolling during excavation on hard rock ground conditions.
The conical shape is preventing damage of the grippers steel during excavation.
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The rear shield has 4 grippers (160mm diameter, 350 bar) with an extended stroke of
150mm.
The rear grippers keep the rear shield in position when the front shield is retracted with the
articulation jack for changing the cutter discs and for ground inspection.
A 270mm-long neoprene tail seal, mounted on the edge of the rear shield, provides leak
tightness between the ground and shield during TBM advance
and grouting of the annulus void between the ring and the
excavated tunnel.
For inspection of the neoprene tail seal, extension of the front
grippers and retraction of the rear shield is required.
The TBM control room placed at back-up 1st gantry is approx.
25m backwards from the excavated face. The operator controls
the front and rear shield to keep them aligned and levelled.
The acceptable tolerance of the segmental tunnel lining from
the Design Tunnel Axis (DTA) is 80mm.
The TBM front and rear shield position is accurately defined by
the guidance system, which records its behaviour in terms of
lead, look-up or overhang and roll.
The TBM is guided by a system of laser sighting (CAP/ZED).
The ZED system uses laser, indicates the Horizontal and Vertical
position of a tunnel-boring machine and transmits this
information to the cap system.
The laser beam is set up and aligned by conventional Theodolite
techniques. The laser beam provides a clearly identifiable line
and a recognizable spot continuously projected on the rear
shield target face by using survey station in the crown of the tunnel.
The Cap system reads these values and the pilot, in manual or automatic mode, tries to
maintain those values by activating the pressures and the flow rate of the pushing jacks, the
speed of rotation and the Cutter Head torque.
In case of important deviation noted by the ZED system, a compensation curve is defined,
which consists in progressively bringing the Tunnel Boring Machine on the theoretical path by
several cycles of boring strokes.
(Earth Pressure Balance TBM)
The assembly of the EPB and back-up gantries took place at Doukissis Plakentias station. The
concrete raft of the station equipped with a sliding path, consists of two steel plates, each to
support the shield of the EPB. The steel plates are placed in concrete parallel to the centre
line of the station raft tunnel.
The basic features of the tunnel are:
Tunnel length
3,374 m.
Minimum radius for alignment
300 m. horizontally, 2,500 m. vertically
Minimum tunnel excavation radius (correction
curve)
250 m.
Maximum tilt
±4%
Outer diameter of excavation
9,490 mm
Inner diameter of lining
8,480 mm
Shield overburden layer
9 m. – 17 m.
The propulsion of the EPB is electric-hydraulic and moves forward by pushing against the last
prefabricated segmental tunnel concrete ring with the 28th shove rams.
The Earth Pressure Balance (TBM) Shield is capable to operate in “open mode” (nonpressurized screw conveyor) and closed mode (pressurised screw conveyor).
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The EPB is divided into two main parts:
Shield
Back-up system
The TBM and Back-Up System is divided into sections for transport and site assembly.
The Shield components are designed to facilitate transportation, assembly and dismantling
operations, including in-tunnel removal and abandonment of the body (skin) for ground
support. All non–replaceable parts have a minimum design life of 10,000 operating hours.
The working pressure is 3 bars and the outer diameter of the shield is 9440mm. The
complete EPB length including the back-up system is 90m.
The TBM shield is designed to withstand all loads and forces occurring from ground
overburden, earth and loads and forces arising during TBM operation, both in normal mode
and in modes required for correcting a 250m radius misalignment.
Deformations caused by any of these loads are limited to allow the
undisturbed operation of the TBM.
Seven numbers of inclined penetrations in shield sleeves fitted with shut-off
valves are spaced around the periphery for angular ground investigation and
treatment.
The TBM shield consists of the front, the centre and the back shield.
The front shield includes the following items:
Cutter Head: The EPB cutter head structure and the main bearing with its
support system are rated to absorb the maximum forces during operation.
The cutter head is an important structure, since it provides the necessary
mechanical support to the tunnel face.
Its necessary abrasion protection features enable the shield to complete the excavation of
the tunnel through the various geological conditions.
The cutter head incorporates the following:
A combination of interchangeable cutter picks (drag bits) and roller cutter discs with
replaceable wear protection.
Manually extended (10–20-30 mm) over cutters.
All cutting tools are designed so that they can be replaced from the rear face of the
cutter head.
To maintain the ground face control with the EPB machine, the excavation starts by rotating
the cutter head and adjusting the floor door openings to a pre-selected width.
As the machine thrust cylinders extend, the ground at the front of the EPB and inside the
cutting head is pressurized.
The earth pressure cells within the cutter head measure this pressure. Once the pressure
exceeds the preset limit, the hydraulically controlled Pressure Relieving Gates are forced to
open, allowing material to pass through these gates and onto the primary conveyor.
Man lock: An air lock conforming to CEN prEN12110 includes a 2-compartment, 4 man main
compartment with 3-bar working pressure.
Shield articulation cylinders: The front shield connected with articulation jacks operated
with 250 bars, which makes it possible to orient the back shield in relation to the front shield
in all spatial directions.
Main bearing: The main bearing is designed to transmit the cutter head torque and thrust
forces. It has a rating of 10,000 hours L10 life and takes into account that the EPB drive
curves have a minimum radius of 250m.
The outer and inner main bearing sealing systems are capable of protecting the bearing for
10,000 hours.
87
A bulkhead designed to act as a pressure vessel end to withstand the hydrostatic soil
pressure of 3 bars, plus any adequate safety margin.
Conditioning agents: When the soil can be conditioned to achieve the necessary plastic
fluidity, it is possible to balance and control the excavation volume against the advance of
the shield.
The conditioning agents are added through the bulkhead to the excavated ground, so that
conditioning can begin immediately and it is ensured that all material in the cutter head
chamber have been transformed so as to achieve the correct consistency.
Conditioning agents, including plain water, bentonite-based mud, chemical polymers and
foaming agents, have been introduced for three principal reasons:
To lubricate the flow of material through the cutter head compartment and the screw
conveyor.
To improve the permeability of the material in very wet ground conditions, so as to
prevent water outflow through the discharge gate of the screw conveyor.
To improve the consistency of the material for easier handling of the muck from the
discharge gate to final disposal.
The foam conditioning material is a compressible
air bubble, encapsulated in a detergent-like (9294%) fluid, which is added to the excavated
material and keeps the particles of the soil apart by
reducing the internal friction and permeability of
the soil.
The centre & back shield incorporate the following
items:
Shove, Pushing rams: The Pushing jacks which
are spaced around the back shield and are grouped
to one shoe, permit articulation and square contact with the segmental tunnel lining.
With reference to the sectioning of the segment lining – 7 standard segments & 1 key
segment-, the number of the necessary jacks is 28, coupled two by two. The 28 thrust rams
have to work in 5 to 7 groups separately.
The hydraulic system of the jacks is designed to provide two working modes in extraction
and retraction speeds:
Advance of the machine (low speed and high pressure) during recycle sequence
Segment tunnel lining erection (high speed and low pressure);
The nominal working pressure in the hydraulic system is limited to 350 bars.
Tail skin: Provision for constant continuous pressure grouting of the annulus of the tunnel
lining with cementation grout through ports in the tail skin.
The grouting behind the segments will be executed simultaneously during boring operation.
A tail seal with grouting system, equipped with a 2-row bolted wire brush seals rated to
withstand a hydrostatic pressure of 3 bars and to prevent leakage of ground water or grout.
The lifetime of the bolted wire brushes is 1 Km of tunnel.
One row of spring steel plates (270 degrees) is provided and installed at the upper side of
the rear shield periphery, from position time 700 clock up to 4oo clock, and another row is
installed between the front and back shield articulation area.
Screw conveyor: The screw conveyor is installed through the sealed Bulkhead into the
cutter head chamber and removes the excavated material during the EPB advance.
When the cutter head rotates, the propulsion system is engaged, and the screw conveyor
starts.
The speed of rotation of the screw conveyor auger determines the rate of excavation while
maintaining control of the excavated face.
89
The excavated material, which is removed via an Archimedean screw conveyor, from the
cutter head-mixing chamber at high pressure, is discharged at the other end of the screw at
atmospheric pressure, onto the first belt conveyor. This is done by controlling the rate of
discharge via the discharge throttle at the upper end of the screw conveyor.
Belt conveyor system: The belt conveyor system removes 650m3/h of excavated spoil
from the screw conveyor in closed or open mode operation.
The excavated material is transferred through the segmental tunnel lining by the conveyor
belt system.
Segment Erector: The segmental tunnel ring is erected after EPB advance by 1.5m within
the tail of the rear shield.
The erector is used for the placement of the pre-cast reinforced concrete segments and is
equipped with a single pick-up head of semi-rotary type.
In case of total loss of power supply (Breakdown), the vacuum system is capable to maintain
(faultless seals) the segmental holding force for 30 min.
The erector is provided with a clockwise and anti-clockwise rotational movement of +/- 200
degrees, spaced equally above the invert of the tunnel.
The erector has a pendant and remote control to provide clear visibility of all erector
movements.
The six degrees of freedom are described here below, in accordance with the design of the
erector, are activated through hydraulic jacks with telescope arms and are operated
separately or simultaneously.
Rotation around longitudinal axis of the TBM (in both direction clock and anti- clock
wise).
Extension.
Longitudinal movement.
Adjustment around longitudinal axis.
Adjustment around radial axis (pitching).
Rotation movement around radial axis.
The erector system has been designed for the installation of one ring within a period of 30
min.
There are two types of conical reinforced concrete rings Left and Right, which allow the
Tunnel lining rings to turn towards left or right, upwards and downwards.
Each type of ring (weight 40.6 tones) consists of 8 PCs of segments, 5 regular segments, 2
counter-segments and one key segment.
The erection of the segments starts at the bottom and alternately, left / right, the ring is built
up to the key segment using the segment erector arm.
The key segment is inserted in parallel with the Tunnel axis at the end of the ring in place.
The conical shape of the left and right rings are designed to have the key segment position
between the upper side 9 to 3 o’ clock.
The elastomeric compression rubber gasket, glued to the mating faces of each segment, is
compressed between segments and rings of the Tunnel Lining and guarantees the water
tightness of the Tunnel.
The segments are bolted together with high strength steel bolts
25mm, 500mm long, with
plastic sockets placed under the bolt washer (80*27*8mm) on each side of the joints.
A concrete segment invert is placed after the ring erection to complete the Tunnel Lining.
Above the invert segments track rails are placed, type 38 kg/m for the sliding of the TBM
back-up gantries and the rolling stock.
The invert segment left as permanent invert is grouted in place by the two grouting pumps
located at the back-up of the TBM.
91
Grouting system: The grouting activities behind the segments are executed simultaneously
during boring operation. The annular void is filled with grout through three positive
displacement single piston pumps “Schwing KSP, 12-2D”. The grout flows easily, while being
pumped under a pump pressure of 2 bars.
The grouting equipment is powered by an electro-hydraulic power pack. The grout is mixed
at the site surface batch plant, is transported into the TBM by the main track trains, in mortar
agitator tanks, and is stored on the frame behind the grouting pumps at the back-up of the
TBM.
Control room: An air-conditioned control cabin is positioned at the gantry one of the backup system, at a distance of 22m from the excavated face.
The control cabin contains all remote controls and indications for the safe operation of the
EPB and its environment.
The operation control cabin has a minimum capacity of 4 persons. It controls, monitors and
records the operational parameters of the TBM and its systems.
A closed-circuit television installed in the control room monitors the following:
The tunnel lining built area.
The transfer of soil from screw to the crusher and to the primary belt conveyor.
TBM end of back-up system.
The control room is equipped with computerized guidance system.
The guidance system SLS-T, relating to the services of the EPB, has been developed by VMT
GmbH.
The SLS-T provides all the important information, which is necessary to drive the EPB along
the designed tunnel axis.
The Maximum deviation of the actual tunnel axis from the design tunnel axis in horizontal
and vertical axes is +/- 40mm.
In case of important deviation noted by the Guidance system, a compensation curve is
defined which progressively brings the EPB machine on the theoretical cycles of boring
strokes.
The back-up system has the following features and possibilities:
Fully decked, closed bottom, where required, with a single-track system and segment
off loading.
The back-up system trailer will run on wheel on track rail.
Cranes for the unloading and transfer of the tunnel lining segments from the delivery
wagons to the segment supply magazine.
Rail lifting and transfer facility for installing the construction rail track and segment
tunnel invert in the invert of the bridge area.
The length of the bridge between the TBM shield and the first gantry is sufficient to
place 9m. long rails and 4 pcs of tunnel invert segments.
Soil conditioning systems and equipment.
The Foam processing plant which consists of the following.
Continuous grouting system. The filling of the annular gap behind the concrete ring.
Tail sealer grease pumping system.
Provision
for
the
extension
of
all
surface
connection
services
(Ventilation,
Communication systems, De-watering pipes, Mains power supply, Compressed air
Cooling water, Generator).
Welfare and toilet facilities to include toilets, washing, mess room.
The ventilation system for the TBM, which consists of one turbo ventilator. The
passage volume is 816m3/min and the cross-section of the ventilation tube 1*
800
mm.
All EPB electrical equipment and installations comply with the European standards and are
designed to operate under the following environmental conditions:
Ambient temperature: 40 degrees.
Dust content: heavily dust laden atmosphere.
Humidity: up to 85% relative humidity.
93
The machines are equipped with a flexible trailing cable (3*95mm) contained on a powered
reeling drum capable of extending up to 250m behind the rear of the EPB back-up system
and the total installed power was app. 3,580 [kW].
OFS (Open Face Shield TBM)
The Open Face Shield (OFS) tunnel boring machine is used to provide initial ground support
when tunnelling is in soft ground, typically clays & silts. It is fitted with forepole blades that,
under unstable ground conditions, can be advanced into the uncut ground in front of the OFS
to support the arch and the face.
HERRENKEHT GmbH designed the Athens Metro OFS named “DAFNI”, for excavation of rock
with maximum unconfined compressive strength (UCS) of 120 Mpa.
The OFS is operating under atmospheric pressure and does not require a closed system for
pressure balance at the tunnel face. The arch of the ground is supported by the skin of the
Shield, ensuring soil excavation, segmental tunnel lining ring erection under safe conditions
and better control of ground settlement.
The OFS consisted of 2 main sections:
Front Shield: including the Forepole blades over 180° arc, in the
top section, road header, two excavating shovels, two telescopic
drilling machines, face rams, twin control cabins and a screw
conveyor.
Rear Shield and tail skin: including segment erector, grout
injection points, tail seal brushes and de-watering equipment.
The OFS can be dismantled in place and the machine parts can be removed in
pieces through the constructed tunnel.
The drive of the OFS main equipment is electric/hydraulic with the following
characteristics:
Overall length of the OFS
12,680 mm
Total Installed Power
4,000 kW
Main Power Supply
20 kV
Total Weight
840 tons
The OFS front section is equipped with a telescopic Road header boom, with 83 picks (in
spiral arrangement) and two telescopic loading shovels.
The Road header and the excavator shovels are controlled during the excavation, through
two identical control cabins. The Road header operator can select individually the extension
of the seven forepoling plates, starting from the tunnel crown for face protection.
The over cutting profile is computer controlled and the excavation cycle time in rock ground
conditions (UCS 70 Mpa) is about two hours. Safety interlocks exist to prevent Road header
operation from the drilling machines operation and the forepole plates during OFS advance.
The excavated over cutting profile (cutting edge of overcut up to 50 mm) by the road header
boom is determined in relation to the present position of the Shield, the outer diameter of
the segments and the requirements imposed by the alignment of the Design tunnel Axis
(DTA).
Each tunnel shove excavation is 1.5m long for placing a segmental tunnel ring and is
performed by two half-shoves 750mm long.
The Road header, telescopic boom has an axial movement of 1100 mm cutting profile in
front of the hood. The road header can reach the lower part profile by retracting the screw
conveyor and using the seven forepole plate’s extension to support the face and the crown.
The rotation of the Road header is in one direction (clockwise).
Water or foam spray and de-dusting system are used to reduce dust during the excavation
mode.
The Forepole blades consist of seven forepoling plates (stroke of 1100 mm up to 1700 mm)
and the seven extending breasting plates arranged in the upper part of the OFS front section
cutting edge.
95
The forepoling plates No.3, 4 & 5 (Crown) can be extended up to 1.7m, the No. 2 & 6 up to
1.4m and the No. 1 & 7 up to 1.1m.
The maximum operating pressure for both extension and retraction movement is 250 bar.
The forepole advance force ranges from 5 up to 127 tonnes and the retraction force from 7
up to 64 tonnes. During the OFS excavation time, the forepole plates operation thrust force is
50 bars (25 tones).
By extending forward the seven forepole plates after excavation, the OFS provides a
sufficient stability in the tunnel crown and support of an almost non-cohesive ground. In soft
ground conditions, the forepoles are used to trim the profile of the ground.
Each forepole plate carries a breasting plate (operating pressure of 250 bar or 100 tonnes)
with four (4) holes of 120mm diameter to allow ground anchoring when plates are fully open
and
to
provide
active
mechanical
support
to
the
corresponding
tunnel
face.
Ripper teeth are placed on the lower part of the front shield skin.
To prevent the possibility of rolling phenomenon, the front shield is adjusted by all thrust
jack cylinders, creates forces hydraulically which lead to correction of the shield position
during tunnelling.
The lower half of the shield is fitted with two face rams (Elephant feet, 2300mm stroke,
holding pressure 300bar).
The excavated material is guided to the screw conveyor hopper by the telescopic excavator
shovels (extension up to 2000mm).
The excavator shovels are mounted on each side of the Road header.
The screw conveyor fixed to the front and rear shield, discharges the excavated material to
the crusher through the primary conveyor belt. The screw conveyor can be retracted and
extended and enables liberation of the screw if any excavated material squeezes it. The
screw conveyor consists of conveyor helix-telescopic station and planetary gearing.
The crusher is installed between the primary and secondary belt conveyor.
The maximum product size after crushing with twin roll sizes does not exceed 200 x 200mm.
The amount of the excavated material for a shovel of 1.5 meter is approx. 192m3 with a
squeezing factor of 1,8.
The excavated material passes through the screw conveyor to the primary conveyor belt (7m
long, 1m wide) located at the level of the tunnel axis and then to the crusher machine.
The second belt is a conveyor belt, 29m long and 1.2m wide, and the third conveyor belt is
38 m long, 1.2m wide and is located on the structures of the back-up gantries and continues
the removal of the excavated materials.
The third conveyor dumps the material to the shuttle conveyor (30 m long, 1.2 m wide),
which moves parallel to the tunnel axis and fills the empty main wagon skips without moving
them.
The conveyor belts are designed for a capacity of 950 t/h (750 m3/h).
The train side tipping spoil cars (Munhlhauser, 6 cars, 30 m3 capacity each) are parked
between the OFS Back-up gantries, dispose the material through the dumping wall, installed
at the site area.
Three gripper pads are fitted to the rear shield body for stabilising the OFS Shield during
segment erection in hard rock conditions.
The gripper pads can be extended up to 150mm with an operating pressure of 300 bars.
The 28 hydraulic thrust rams (arranged in 14 x 2 pieces) are positioned in a way that they
can support the prefabricated concrete tunnel segments used during erection.
A total thrust of 5,600 tons (Power 2 x 160kw) is available from the thrust rams to advance
the shield by pushing against the pre-fabricated segmental tunnel ring.
Two rows of wire brush tail seals are fitted to the rear shield supplied by grease,
excluding the ground water and the primary grout from re-entering the Rear Shield.
The Tail Shield skin thickness is 70 mm.
97
The greasing system is controlled automatically by means of pressure sensors.
Two emergency pumps 35KW (400volt) are installed at the segment erection area to
evacuate the water.
The TBM control room placed at back-up 1st gantry is about 25m backwards from the
excavated face.
The operator controls the front and rear shield to keep them aligned and levelled.
The acceptable tolerance of the segmental tunnel lining from the Design Tunnel Axis (DTA) is
80mm.
ROLLING STOCK
First Generation of Trains
GENERAL INFORMATION
Number of Trains
28 (Lines 2 and 3)
Train Composition
6 Cars
Doorways per car
4 per side
Train Capacity
Customer Amenities
224 Seats
806 Standees (5 Passengers/m2)
1030 Passengers / Train
Forced Air Ventilation
Automated Station Announcements
TECHNICAL FEATURES
Train Configuration
Two 3-car units coupled back-to-back
Driving Trailer- Motor Car- Motor Car
Train Length
106m
Car Width
2800mm
Car Height
3600mm
Interior Headroom
2180mm
Train Weight
178 tons empty
245 tons fully loaded
Gauge
1435mm
Operating Voltage
750 VDC
Traction Motors
4-153kw DC motors per motor car
Traction Controls
DC Chopper / microprocessor controls
Braking
Regenerative-Dynamic / pneumatic
Average Acceleration
1.00m / s2
99
Average Deceleration
1.08m / s2 (Normal)
1.20m / s2 (Emergency)
Maximum Speed
80km/h
Car body Construction
Stainless Steel
COMMERCIAL INFORMATION
Contractor
OLYMPIC METRO Consortium
Major Rolling Stock Suppliers
SIEMENS
ABB- DAIMLER-BENZ
GEC/Alsthom
Primary Manufacturing Locations
Nurnberg, Germany
La Rochelle, France
Second Generation of Trains
GENERAL INFORMATION
Number of Trains
21 (7 DC/AC Trains and 14 DC Trains)
Train Configuration
6 Cars
Doorways per Car
4 fitted type sliding doors per side
DC Train Capacity
196 Seats
866 Standees (5 Passengers /m2)
1062 Passengers /Train
DC/AC Train Capacity
158 Seats
868 Standing (5 Passengers/m2)
1026 Passengers/Train
Passenger Amenities
Air Conditioning Units in Trains
Destination signs inside the trains with provision for
alternating messages
Areas designated for the exclusive use by Persons
with Special Needs
Wide gangways allowing for balanced distribution of
the riders' load within the vehicles
Door open pushbuttons which are operated by the
passengers in off-peak hours
Strict noise limits
TECHNICAL FEATURES
Train Configuration
Two three (3)-car units coupled back to back
Driving / Motor Car - Trailer Car - Motor Car
Train Length
106m
Car Width
2800mm
Car Height
3690mm
Interior Headroom
2100mm to 2200mm
DC/AC Train Weight
202 tons empty
275 tons (5 Passengers/m2)
DC Train Weight
182 tons empty
255 tons (5 Passengers/m2)
Gauge
1435mm
DC/AC Train Operating Voltage
750VDC/25kVAC
DC Train Operating Voltage
750VDC
Traction Motors
4
DC/AC Train Traction Controls
Converter AC-DC, VVVF Inverter (IGBT technology)
DC Train Traction Controls
VVVF Inverter (IGBTtechnology)
Braking
Regenerative/Dynamic/Pneumatic
Average Acceleration
1,00m/s2
Average Deceleration
170kW AC per driving motor
1,1m/s2 (in normal conditions)
1,20m/s2 (in emergency conditions)
Maximum DC/AC Train Speed
120km/h
Maximum DC Speed
80km/h
Carbody Material
Stainless Steel
Other Information
COMMERCIAL INFORMATION
Comprehensive Fault Indication and Identification
System
Simulated revenue service tests
Reliability proof program
101
Contractor
Major Rolling Stock Suppliers
HANWHA-Rotem Consortium
MITSUBISHI
VAPOR
KNORR-BREMSE
Main Manufacturing Countries
S. Korea, Japan
Delivery
2004
Third Generation of Trains
The tender for the supply of 17 new 6-car trains to meet the network needs following the
completion of the new Metro extensions is in progress. The new trains shall be equipped with
state-of-the-art systems, shall be air-conditioned, environment-friendly, and properly
equipped to ensure compatibility with all future technological upgradings in Athens Metro
Lines 2 & 3.
ELECTROMECHANOLOGICAL SYSTEMS
Facilities
An extensive network of E/M systems and special equipment has been installed, aiming at
the smooth operation of the Metro system and at the safe and comfortable transportation of
the passengers, as well as at securing the proper work conditions for all Metro employees.
This network includes the following systems:
Ventilation
The Metro ventilation system is divided into two categories, i.e., the Tunnel / Station
passenger areas ventilation system, and the other individual ventilation systems for the
Personnel areas and the technical rooms located within each station. The Tunnel / Station
passenger areas ventilation system serves two purposes: one purpose is to supply fresh air
for ventilation under normal operation conditions, and the second purpose is to extract
smoke in case of emergency. Moreover, the various other ventilation systems in the Depots
and the Stations, which include more than 200 local fans, ensure the smooth operation of the
technical equipment, as well as the proper living conditions for the Metro operation
personnel.
Air Conditioning - Heating
Heating / air conditioning units are installed in all Stations and Depots of the Metro, offering
an ideal work environment for the personnel as well as for certain areas with sensitive
equipment. The Passenger areas within the Stations do not require heating during the winter
months, since, on the one hand, the entire Metro network is located at a great depth not
susceptible to extreme temperature variations, and, on the other hand, the constant
operation of the technical equipment releases additional heat. Moreover, all Metro stations
are equipped with spare rooms, which can be fitted in the future with air conditioning units,
cooling the air supplied to the passenger areas of each station.
Pumping Stations
In each Metro station and at all low points within the tunnels, double pumps for rainwater
have been installed; this rainwater either comes from the surrounding ground, or flows in
through the station openings at street level. In addition, each station is equipped with a pair
of wastewater pumps.
Fire Protection
In all installations of Attiko Metro, provision has been made for a series of passive and active
fire protection measures, in order to minimize the possibility for the outbreak of a fire, as well
as to effectively deal with such. The fire protection system and equipment are designed and
constructed in close cooperation with the Fire Department. Before inception of revenue
operation, all Attiko Metro installations are inspected by the Fire Department and the relevant
Fire Protection Certificate is issued.
Lighting
Thousands of lighting fixtures installed in the stations generate a high luminosity, creating
thus a safe and pleasant means of public transport. Battery-operated emergency lighting is
provided in all areas, capable to cope with power failures for a period of two hours.
103
TECHNICAL DETAILS ABOUT AUTOMATIONS (GENERAL DESCRIPTION OF THE
BUILDING AUTOMATION AND CONTROL SYSTEM-BACS)
The purpose of the BACS system is to monitor all tunnel ventilation systems, Station,
Heating, Ventilation & Air Condition (HVAC) systems and all E/M systems within
stations,shafts, and tunnels of the Metro lines and extensions, which are currently in
operation or in the phase of construction or tendering, under normal operation emergency
conditions; these systems are the following:
Concerning the Base Project :
Ventilation System for tunnels and Blast Shafts:
Supply Air Fans (SAF)
Under-platform Exhaust Fans (EXF-P)
Intermediate Shafts Exhaust Fans (EXF-I)
Motorized Dampers
Fireman’s Box (FB)
HVAC System:
Technical Rooms and other areas Exhaust Fans (EXF)
Air Handling Unit (AHU)
Water Chillers
Air Conditioning Unit (ACU)
Motorized Dampers (MD)
Interface with Fire Detection Switchboards
Concerning the Phase A’ Extensions :
Ventilation System for tunnels and Blast Shafts
Blast Shaft Fans (BSF)
Under-platform & Overhead Exhaust Fans (UPE)
Jet Fans (JF) in Tunnel
Roller Shutter Doors (RSD)
Motorized Dampers (MD)
Fireman’s Box (FB)
HVAC System:
Exhaust Fans (EXF)
Motorized Dampers (MD)
Cooling machines with their associated pumps and installations
Heat Pumps (HP)
Fan Coil Units (FCU)
E/M System:
Uninterrupted Power Supply (UPS)
Normal and Emergency Lighting
Pumping and drainage systems
Hydrants, deluge valves and pipes (DEV)
Lifts
Escalators
Interface with Fire Detection Switchboards
Interface with the Intrusion Detection System
Signaling
105
GENERAL INFORMATION
Automatic Train Protection (ATP)
Automatic Train Supervision
Ensures train breaking / cab signaling
Central CAD Control, with Automatic Route Setting and
Positive Train Identification
TECHNICAL CHARACTERISTICS
Interlocking (IXL)
Geographic, relay-type interlocking (Base Project) – Electronic
Interlocking controlled by a computer (Extensions)
Automatic Train
Automatic Train Protection, with constant calculation and monitoring
Protection (ATP)
of the train speed, according to the conditions on the track
Cab Signaling
Audiovisual warning and speed control according to the signals
µ
Selective frequency and phase AC track circuits in the depot areas.
Track circuits
Remotely-controlled audio frequency track circuits in the areas
controlled by the ATP
Signals
Turnouts
Passenger Information
System (PIS)
Double-faced signals with filaments (Base Project), Double-faced
Light Emitting Diode (LED) signals (Extensions)
Motorized point machines, with the option for manual control
Electronic boards on the platforms showing the train arrival time
Operation Control Center Automatic Train Supervision and time-table control. Mosaic Mimic
(OCC)
Local Control (Low)
Uninterrupted Power
Supply (UPS)
Panel. Computer terminals with detailed monitors and keyboard input
Local Control Panel, mosaic type (Base Project), Local Workstation
controlled by a computer (Extensions)
Six-hour autonomy throughout the Metro network
1. Central Control (Syntagma)
Modes of Operation
2. Local Control (Shunting Station)
3. Manual Control
Communication Systems
In an underground urban railway system, the efficient and reliable operation of the
telecommunications is of paramount importance to the operation of the entire Metro system.
Even though there are acceptable telecommunications systems for a wide range of
application, only those systems that fulfill the highest standards of manufacture and the
special requirements concerning the operation of the railway and the associated installations
are suitable to be used in the Metro Base Project.
Moreover, the appropriate provisions have been made during the design and installation of
the equipment in the extensions of lines 2 and 3, so that these systems are fully compatible
with the already operating systems of the Base Project.
Automatic Telephone System
It consists of a telephone exchange system, whereto PRIMARY-ISDN type lines are
connected, serving the wire communications needs.
Direct Telephone Line Personnel
Telephone sets for: Communication is cases of emergency and Maintenance
Traction Power Removal devices
Direct Telephone Line
Telephone sets installed on the platforms
Radio Communication (Wireless TETRA system)
Maintenance
Police
107
Depot
Radio
communication
consoles
in
the
control center and the depots
Radio communication consoles in the Cabs
of new Trains
Portable
Monitors for (Closed Circuit TV - CCTV)
Cameras in the Concourse and Platform areas, as well as in the Cash Counting
Room
Information Controller in the OCC
Police in the OCC
Police for the protection of cash
Station Masters
Tarin Drivers
Provision for Future Extensions
Public Address System (PA). Announcements from:
OCC
Station Masters
Platform Announcement Point
Information Controller in the OCC
Distribution System
Digital Management System
Spare Fiber Optic Cable
Fare Collection System
GENERAL INFORMATION:
Flat
fare
and
Free
Transfer
with
Time
Installed infrastructure for:
Fare Structure
Future zonal fare
Use of SmartCart as per Calypso technology
Fare Collection Method
Self-service, Receipt
Ticket Sale / Validation in the Concourse area
Limitation
Sampling
Single-Trip Normal Fare
Single-Trip Reduced Fare
Type of Fare
Monthly Pass
Free Pass
Automatic Ticket Issuing Machines
Single-Trip Tickets
Ticket / Card Sale
Ticket Booths in all Stations, selling ticket bundles and Cards
TECHNICAL CHARACTERISTICS:
Single Tickets of variable value
Acceptance of Notes
Return of change
Ticket Issuing Machines
Accepting 5 types of coins
Ready to accept Smart Cards as per Calypso technology
Manual Ticket Issuing Machines
Method Manual Ticket Issuing
Suitable for use by ticket sellers
Machines
Operating on a shift basis
Printed validation
Ticket Validation Machine
Accounting Control / Monitoring &
Fault Indication
Ready to accept Smart Cards as per Calypso technology
All devices are part of a network at a Local and Central Level
Traction Power Supply System
TECHNICAL CHARACTERISTICS:
109
A. MEDIUM VOLTAGE (MV) POWER
Source
Public Power Corporation (PPC)
Power Supply Voltage
20 kV, 3 , 50Hz
Power Supply Points
30
Power Distribution
70 mm2, copper cable
B. DIRECT CURRENT (DC) RECTIFIER SUBSTATIONS
Rectifier types
12-pulse rectifiers with silicon diodes
10 (Line 2)
Number of substations
10 (Line 3)
2 (Depot)
22 in Total
1100 m (Line 2)
Average spacing
Power
1200 m (Line 3)
3 MW
150% for 2 h
Overloading capacity
Output voltage (nominal)
300% for 1 min
750 VDC
C. DC POWER DISTRIBUTION
60 Kg/m, low carbon content steel
Third Rail
17.3 Kg/m, Composite (Aluminum / Stainless Steel)
Nominal voltage
750 VDC
Minimum voltage
525 VDC
Maximum voltage
900 VDC
D. OTHER CHARACTERISTICS
Capacity design
6-car Trains, 100s Headway
The entire third rail of the Main Lines:
Sectionalization
Line 2 - 18 sections
Line 3 - 14 sections
Remote Control (Syntagma)
Monitoring & Control
Local Control
Emergency plungers every 200m
Track work
The trackwork in the Metro tunnels comprises the elastic support
track, fastened on concrete track-bed (Fixed trackwork).
The tracks have a standard gauge of 1435mm, made by UIC 54 rails,
fastened on bi-block sleepers – with microcellular footing and rubber
boots – semi-embedded into the trackbed concrete. In addition, the
third rail along with its protective cover is fastened on the sleepers,
by means insulated brackets. Underneath the trackbed concrete
there is a mesh for the collection of stray currents, embedded into
the concrete of the tunnel invert. Concrete cable ducts are
constructed at both sides of the tunnel; these ducts and their
precast covers form the tunnel’s walkway.
The turnouts / crossovers are now installed using the direct fixation system on the concrete
slab. Moreover, wherever necessary, measures for noise and vibration mitigation are
implemented. In these areas, the turnouts / crossovers and the plain track sections are
placed on floating slabs.
In the open-air areas of the Depots, the turnouts / crossovers are installed on wooden or
concrete sleepers on ballasted track.
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