The Taiwan High Speed Rail (HSR) System is a fully electrified
domestic passenger railway between Taipei, the capital city in the
north, and Kaohsiung, the second largest city in the south on the
island of Taiwan, Republic of China (ROC). The HSR is planned to
open in October 2006 and is not yet in revenue operations. It will
improve travel times along Taiwan's western corridor significantly,
with the express service travel time between the termini, a distance
of 345 km (214 miles), being 90 minutes.
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Acronyms in Article:
HSR: High speed rail
IV&V: Independent erification and validation
ROC: Republic of China
SES: Sequential excavation andsupport
THSRC:Taiwan High Speed Rail Corporation
TRUPO: Taipei Railway Underground Project Organisation
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PB is providing a range of project management, construction management
and engineering consultancy services, including second of specialists
is systems assurance/system safety to support Safety Case development
and certification activities.
Overview of the System
The HSR passes through or close to Taiwan's main cities, manufacturing
areas, and business and administration centres, crossing a mix of
agricultural land, freeways, rivers, military bases, residential
areas and open countryside-all of which present unique engineering
problems requiring unique solutions. Approximately 75 percent of
Taiwan's 23 million people live along this western corridor.
The HSR system incorporates proven Japanese technology and features:
- A 350 km/hr (217 mph) design speed and maximum operating speed
of 300 km/hr (186 mph)
- Trains operating at a minimum headway of 3 minutes at peak
service
- Twelve-car train sets seating around 980 people, thereby providing
360,000 seats per day
- Automatic train control
- Electronic reservation and ticketing
- Safety monitoring devices for earthquakes, wind, rain, rock-fall,
landslide, and vehicle intrusion.
Due to some of Taiwan's unique geographic features-the route crosses
three active earthquake faults-there is potential for soil liquefaction
in certain areas and tunneling conditions were difficult in a mountainous
sub-tropical environment with dense forestation.
The structure types along the 345-km (214-mile) total HSR route
length are:
- 251 km (156 miles) of viaducts and bridges (73 percent of total
length)
- 31 km (19 miles) of at-grade railway (9 percent of total length)
- 63 km (39 miles) of tunnels (18 percent of total length).
These structures include the existing 15.8-km (9.8-mile) Taipei Railway
Underground Project Organisation (TRUPO) Section, which is a fixed
facility built by the ROC Government (through the Reconstruction Bureau
of Taiwan Railway, Ministry of Transportation and Communications,
and the Bureau of High Speed Rail). The TRUPO section was built to
accommodate both the Taiwan Railway Administration and HSR systems
on their underground approach into the Taipei metropolitan area in
an effective operationally shared environment. The HSR approach passes
through the intermediate Banciao Station structure with Taipei Main
Station acting as the initial northern terminal for HSR revenue services.
The southern section of the line is remarkable in that it is located
on a continuous viaduct for a length of 157 km (97.3 miles) with
the the deck level approximately 10 m to 15 m (32 feet to 50 feet)
above ground (Figure 1). It is the longest continuous railway viaduct
in the world.
The HSR system, as the one illustrated in Figure 2, was split into
seven major contract areas during the design and construction phase,
namely, civil works; stations; depots and depot equipment; track works;
core system, and automatic fare collection system and related contracts.
Initially eight stations (six new, and two with modifications to
the existing) will be opened along the HSR route in October 2006
for planned revenue operations. Three additional stations in citie
outside Taipei are planned for the future.
The core system for the HSR includes rolling stock based on the
hinkansen Series 700 (Figure 3), a bi-directional signaling system,
a 25kV 60Hz AC overhead catenary electrification system, communication
systems and the operation control system. The central control function
for the HSR system is located at the operation control centre beside
Taoyuan Station, located near Chiang Kai Shek International Airport.
Rails using continuously welded section were laid on resilient pads.
Rail expansion joints are located where required to accommodate earthquake
movements. Maintenance facilities for train-set repair, servicing
and cleaning, track and other infrastructure have been provided at
various locations along the HSR route. The HSR has been designed,
constructed and will be operated in ccordance with the Construction
and Operation Agreement. This is a contract executed in July 1998
between Taiwan High Speed Rail Corporation (THSRC) as a privately
held company and the ROC government that grants the concession to
construct and operate the HSR to THSRC. The concession is exclusive
and will operate for 35 years.
Challenges of the HSR System Civil Works
Tunnels. The HSR system has more than 50 tunnels,
including 39 mined tunnels. The three longest ones are:
- Paghuashan Tunnel, 7.4-km (4.6-miles) long
- Linkou Tunnel , 6.4-km (4.0-miles) long
- Hukou Tunnel, 4.3-km (2.7-miles) long.
There are no vertical low points except in those tunnels in urban
areas and the number of high points have been minimised.
All tunnels have a cast in-situ reinforced concrete lining over
their length that was designed to prevent deterioration of the rock
and to support the rock mass. The lining either forms a controlled
path to duct any groundwater to an invert drain (in the case of
a drained tunnel), or is designed to prevent water from entering
the tunnel (in the case of an undrained tunnel).
The tunnels have been provided with portal collars to prevent rock
or debris falling from the portal onto the track. Portal structures
are inclined at least 45 degrees from the vertical to mitigate aerodynamic
effects. For the Hueilung Tunnel and all tunnels longer than 3 km
(1.9 miles), a pressure relief portal structure has also been provided.
Typically, the tunnels encountered geological conditions varying
between soil, gravel and sedimentary rock, or combination
of these conditions. They were excavated mechanically
and are either the mined or cut-and-cover type. The
mined tunnels were advanced using the sequential excavation
and support (SES) construction method, which the contractors
selected as themost suitable excavation method for the tunnel
size and geometry
(Figure 4).
Even though it is considered a labour-intensive technique, the
conventional SES method was identified as the most advantageous
in terms of schedule. The tunnel cross-section was excavated
in stages, reducing the open surface of each face, which
typically consisted of heading, bench, and invert stages, and thereby
reducing the potential of collapse. An excavation diameter approaching
15 m (50 feet) resulted in a temporary excavation cross-section
of between 120 m2 to 140 m2 (approximately
1,300 square feet to 1,500 square feet) to accommodate the permanent
works housing the double tracks.
The finished tunnel cross-section area in all tunnels bar Hueilung
Tunnel and Linkou Tunnel is a minimum of 92 m2 (990 square
feet) to accommodate the aerodynamic requirements associated with
the high-speed train travelling at 300 km/hr (186 mph). The tunnel
finished cross-sectional area also allows for a minimum of a 1.2-m
(4-foot) safety walkway on either side of the tracks for emergency
evacuation and a safety area for maintenance personnel.
Viaducts and Bridges. The HSR system viaduct design
and construction generally incorporates bored cast-in-place piled
foundations, or footings supporting single or multiple reinforced
concrete columns. The piles, pile caps and columns were constructed
in-situ. The guideway/deck beams were either pre-cast or cast-in-place.
The viaduct construction was based upon more than 30,000 piles
ranging in depth from 35 m to 72 m (115 feet to 236 feet) and in
diameter from 1.5 m to 2.5 m (5 feet to 8 feet). The average viaduct
deck width is 13 m (42.5 feet) with approximately 140 km (87 miles)
of pre-cast decks.
The majority of the guideway decks/beams weigh approximately 700
tonnes each. Techniques used in deck construction include the full-span
pre-cast launching method, free cantilever method/balance cantilever
method, movable scaffolding system/advance shoring method, and full
support method.
Twelve steel truss bridges are distributed across the HSR system
comprising 17 spans for a total length of 2533 m (8,310 feet). The
majority of these bridges have spans ranging from 55 m to 150 m
(180 feet to 497 feet) to satisfy specific site conditions, such
as crossings for significant highways, railways, rivers and ravines.
The trusses are generally of the Warren Girder type with overhead
plan bracing provided. The decks generally consist of an in-situ
reinforced concrete slab, which is constructed integrally upon a
grillage of cross-girders, the lower chords (girders) of the main
trusses, and longitudinal stringers.
The design requirements for the steel truss bridges include the
following:
- All welded connections for chord and bracing sections are made
in the shop.
- All site connections are bolted.
- The minimum design life to first maintenance is 20 years for
bridge structures supporting or crossing the HSR line.
- Structural members are sized to avoid excessive noise emission,
and they are detailed to avoid dirt and moisture traps.
- Special requirements for flanges, joints and stiffeners were
specified to avoid fatigue.
Verification and Validation
The above discussion illustrates some of the technical civil works
challenges faced by THSRC and its civil works contractors who were
responsible for both the design and construction. To provide "systems
assurance," including "quality assurance," THSRC
has implemented a checking and audit system that calls for designs
and calculations, construction methods and testing, etc., to be
checked throughout the procurement of the civil works. This system
is enforced by use of the contractor's independent checking engineer
and the THSRC-employed independent checking engineer and independent
site engineer.
In addition to the formal checking procedures described above,
the whole design and construction process for the HSR project is
subject to the close-out monitoring and assessment procedures of
RAMS (reliability, availability, maintainability and safety) requirements
specified in the major HSR contracts. THSRC will also assess and
audit the whole HSR project. The arguments and evidence for systems
assurance/system safety will then be presented in the THSRC Railway
Operational Safety Case Report.
As an additional and final check, a fully independent overall verification
and validation assessment is underway. THSRC has appointed an independent
verification and validation institution (IV&V), to examine and
assess the planning, design, construction, commissioning and preparation
for operation of the HSR. The IV&V will confirm, by certification,
that the basis of the chosen design is valid and that it has verified
that THSRC's safety, RAM, functional, and quality requirements have
been complied with according to the Construction and Operation Agreement.
The IV&V will report to THSRC and Bureau of Taiwan High Speed
Rail and is completely independent of all parties, including contractors
and consultants engaged on the HSR project. |
