9.5 C ONSTRUCTION SCHEDULES
9.5 Construction schedules
9.5.1
Introduction
A preliminary scheduling exercise has been conducted for the construction of the CLIC complex (Main
Linacs, injectors, experimental areas and infrastructures), based on the experience acquired during the
construction of large accelerator and experimental facilities for particle physics, particularly the LHC
machine, the CMS detector and several linac projects at CERN. As an example, Table 9.1 shows a number
of similarities between the experimental areas of CLIC and CMS, warranting the proposed method for
the schedule study.
Table 9.1: Similarities between the CLIC and CMS experimental areas
CMS
2 experimental caverns
2 access shafts
2 surface assembly halls
1 bypass tunnel
2 evacuation galleries
2 survey galleries
2 Modular Detectors (ILD, SiD like) – 7 elements
1 experimental cavern & 1 service cavern
1 access shaft & 1 experimental shaft
1 surface assembly hall
1 bypass tunnel
2 evacuation galleries
2 survey galleries
1 modular detector – 13 elements
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CLIC
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Two targets were set for the CLIC schedule exercise, within the constraints and boundary conditions stemming from the experience acquired with past CERN projects: 1) construct, install and commission as fast as possible a 3 TeV center-of-mass machine, and 2) include a first intermediate stage at
500 GeV center-of-mass, the commissioning and operation of which should not bring additional delay to
the 3 TeV center-of-mass programme.
9.5.2
9.5.2.1
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The scheduling exercise and its results are presented in the following: the total time required for
the construction, installation and commissioning of CLIC at 500 GeV is 7.25 years, while the 3 TeV
machine can be built in about 10 years. The sequencing of the various installation activities has been
studied in some detail, in order to minimize interferences and consequently the amount of time lost. The
schedule exercise includes the preparatory phases (e.g., environmental impact study, invitations to tender
and launching of industrial procurement).
Preparation
Environmental impact study
In view of the size of the project, and of the applicable legislation and regulations in many countries, the
project will require an environmental impact study and corresponding public enquiry as a prerequisite
for authorization. As an example, for an implantation in the vicinity of the CERN site, we have considered the application of the French procedure, previously experienced for the LEP and LHC projects.
Establishing the environmental impact study documents and conducting the public enquiry would take
around one year, after which a delay of six months is needed to obtain agreement from the central French
authorities (‘Conseil d’Etat’). An equivalent amount of time is considered necessary for acquiring land,
negotiating rights of way with the local owners and obtaining work permits.
9.5.2.2
Procurement of series components
The construction schedules take into consideration the production capacities of the main components,
especially those with very large numbers such as the accelerating structures. For the 3 TeV center-ofmass machine, meeting the schedule requirement of not unduly delaying installation requires to complete
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production of the 142 760 accelerating structures within 65 months of contract adjudication. Assuming
the total procurement is split among three companies, and considering overcapacity for imperfect production yield and times for set-up and ramp-up of production, leads to a cruise production rate of 925
accelerating structures per month and per company (Fig. 9.1)
Fig. 9.1: Production of accelerating structures for each out of three suppliers
Main linacs
9.5.3.1
9.5.3.1.1
Rates of progress and logistic constraints
Civil engineering
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9.5.3
The civil engineering works schedule is based on a study performed by an external consultant (Amberg
Engineering) in 2008. The following progress rates are retained for the CLIC complex construction:
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– Site installation : 15 weeks
– Shaft excavation and concrete:
– 180 m deep: 30 weeks
– 150 m deep: 26 weeks
– 100 m deep: 15 weeks
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– Service caverns: 35 weeks
– Excavation by tunnel-boring machine (TBM): 150 m/week
In order to ease logistics and preserve personal safety, the construction of the main linacs , injectors
and experimental area constitute separate civil engineering work batches. Few weeks before the dates of
civil engineering handover, geodesic measurements will be performed, which are crucial in view of the
large geographical extent of the machine and its tight requirements in matters of alignment.
9.5.3.1.2
Installation of general services
The general services in the main linacs consist essentially of the following:
–
–
–
–
Survey: marking the position on floor (one point every 2 m) – 9 weeks/km/front;
Electrical general services: lights, cable trays, and power boxes – 8 weeks/km/front;
Cooling & ventilation: ventilation ducts and pipes – 8 weeks/km/front;
Cabling: both AC and DC - 8 weeks/km/front.
9.5.4 Installation of two-beam modules
– The modules will be transported to their final locations in the tunnel at a maximal rate of 550
modules per month
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9.5 C ONSTRUCTION SCHEDULES
– The interconnections will follow, starting at a maximal rate of 300 modules per month (for the
intermediate stage at 500 GeV center-of-mass) and reaching a maximal rate of 400 modules interconnected per month.
9.5.4.1
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Fig. 9.2: Two-beam modules for the main linacs: from production to interconnection
Schedule
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The CLIC complex will be built in four main phases:
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1. Civil engineering phase: after almost four months of site installation, excavation of the main
shafts will start. The two tunnel-boring machines will be mounted on site and will start the excavation of the right and left tunnels. As soon as one shaft is no more used for earth removal, the
concrete works will start followed by installation of the ventilation ducts and finishing.
2. General services phase: the handover by civil engineering of the different areas will be followed
by the determination of the tunnel geodetic network and the marking of positions on the floor;
it will be immediately followed by the installation of the general electrical services, piping, and
cabling. The worksites will develop sequentially (with a small overlap) in order to ease logistics
and avoid risky co-activities. At any given time, each general service activity will proceed along
four fronts, in parallel in two sectors (right and left).
3. Machine installation: once most of the cabling work is completed, installation of the ground supports will start. The two-beam modules will then be transported, pre-aligned and interconnected,
working in two fronts in each sector.
4. Commissioning phase: this phase involves commissioning of the accelerator systems without
beam; it will last around one year and will be followed by a final alignment of the machine.
9.5.5
Injectors
Construction, installation, and commissioning of the injectors will last around six years. Detailed schedules have been drawn up based on the studies performed for smaller accelerator projects at CERN.
9.5.5.1
Pre-damping and damping rings
The construction and installation of the pre-damping and damping ring complex will last four years and
will be followed by commissioning.
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Fig. 9.3: General ‘railway’ schedule for the main linacs
Fig. 9.4: Gantt generic schedule for the pre-damping and damping rings
Fig. 9.5: Gantt generic schedule for the main beam injector complex
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9.5 C ONSTRUCTION SCHEDULES
9.5.5.2
Main beam injector
The construction and installation of the main beam injectors will last three and a half years and will be
followed by commissioning.
9.5.5.3
Drive Beam
The same strategy will be applied for the construction and installation of the Drive Beam facilities.
9.5.5.4
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Fig. 9.6: Gantt schedule for the drive beam injector linacs
Summary schedule for the injectors
Experimental areas
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9.5.6
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The schedule of the injectors is presented in Fig. 9.7. The start of construction of each complex has been
adapted in order to level the resources, while keeping compliance with the main linac schedule. It must
be noted that for coherence of the civil engineering works, construction of the long descending transfer
lines (black arrow in Fig.9.7) must be completed in the time window between the end of excavation of
the main tunnels and their handover for installation of infrastructure.
A seven-year program has been established and is presented in Table 9.2.
In the course of year 4, the work in the shaft area of the assembly halls will have to be interrupted
for 12 weeks to allow for the installation of important parts of the shaft technical infrastructure such as:
prefabricated concrete modules for lift and stairway, ventilation ducts, cooling pipes, cable trays, and
metallic staircases for the shaft technical area.
Figure 9.8 shows a Gantt chart form of the schedule for this period.
A lot more work is needed to work out the details of this schedule but the current sequence seems
to be compatible with the goal of being ready for beam at 500 GeV center-of-mass seven years after the
kick-off of project construction.
9.5.7
Overall schedule
The overall ‘railway schedule’ combining construction of the Main Linacs, injector complex and interaction region is given in Fig. 9.9. Beam commissioning and operation of the 500 GeV stage could start
in year 8 and continue in year 9, in parallel with further installations occurring in the left and right extensions of the Main Linac tunnels. However, the requirement to reach 3 TeV center-of-mass as soon as
possible would then interrupt further the operation of the machine at 500 GeV center-of-mass.
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Fig. 9.7: Summary schedule for the injector complex. The central column (black arrow) refers to the long descending transfer lines from the injector complex at ground level, to the main tunnels underground
Fig. 9.8: Details of schedule in year 4
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9.5 C ONSTRUCTION SCHEDULES
Table 9.2: Construction and installation of CLIC Interaction Region
Surface work
1
Excavate two experimental shafts in
parallel
2
Excavate and carry out finishing of experimental caverns and transfer tunnel
(2.5 years)
3
Proceed with finishing of the two experimental Caverns and transfer tunnel
Construction of part (2/3) of two detector assembly halls in parallel, including
services
Assemble 2 Detectors in their dedicated Assembly Halls (1st of 4years)
Construct service buildings (Cooling &
ventilation, Electrics, Gas, Counting
rooms. . . )
Assemble two detectors in assembly
halls (2nd of 4 years)
4
Complete finishing of the two experimental caverns and transfer tunnel
Install infrastructure and services in
two experimental caverns and transfer
tunnel (1.5 years). See details in figure
6.2.9-5
Complete installation of infrastructure
and services in two experimental caverns and transfer tunnel
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Underground work
Assemble two detectors in assembly
halls (3rd of 4 years)
Complete construction of last third of
two assembly halls
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Year
6
Connect two detectors to the caverns’
on-detector services & cable chains (6
months)
7
Perform magnet tests
Trial run with cosmic rays
Commission safety systems
Test push-pull system including forward shielding
7
Complete assembly of 2 detectors in
assembly halls
Installation of heavy load gantry crane
for lowering detectors
Lower two detectors (6 months)
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Fig. 9.9: Overall ‘railway’ schedule
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