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- 2 -
AP IX-64-E
Recommendation L.11
JOINT USE OF TUNNELS BY PIPELINES AND TELECOMMUNICATION CABLES,
AND THE STANDARDIZATION OF UNDERGROUND DUCT PLANS
The CCITT,
considering
(a) that many countries are interested in the joint use of tunnels
and are aware of the advantages, disadvantages and specific dangers they
hold out;
(b) that the rules governing this type of ducting vary significantly
from country to country;
(c) that the importance of the joint use of tunnels increases with
density of population and shrinking green spaces, i.e. in large towns;
recommend
that administrations who in future will be interested in this type of
installation, follow the rules described in this Recommendation.
1. General considerations
Duct tunnels and trenches are constructions containing one or generally
more ducts belonging to different networks. Inspectable tunnels include one or
more gangways for initial assembly work and subsequent control, maintenance and
repair operations. A tunnel without standing room designed for crawling should have
a clear internal height of at least 0.8 m. Duct gangways may not be entered.
The above principles apply to inspectable tunnels, and apply by analogy
to tunnels with crawling room only.
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- Ducts, Network, Dimension (cross-section), Power (capacity),
Material, Protection against corrosion, Number, Distribution priority, Duct
routing, Compatibility with other ducts, State of ducts, Repairs,
Overhaul, Replacement, Reserves, Extensions, Emergency ducts,
Provisional installations, Connections to buildings;
- Roadway, Road width, Pavement width, Green strip, Traffic density,
Surface water drainage, Superstructure;
- Subsoil, Type of ground, Groundwater level, Existing ducts, Existing
underground constructions;
- Schedules, Beginning of works, Duration of works (stages), Start-
up.
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devices should be provided at appropriate locations.
High temperatures may occur in tunnels containing heat evolving ducts.
Care should be taken to maintain physiologically acceptable environmental
conditions in order to avoid any impairment to health during work or inspections. For the
telecommunication cables, see 3.3.2.
considered in the light of CCITT Recommendation L.1 [1] Metal components
(pillars, racks or supports) should be preferably be made of hot galvanized steel. In
some cases, cathodic protection may be applied.
(see section 5).
- Protection against thermal load
Since telecommunications cables are vulnerable to thermal load, thermal
conditions in tunnels must be taken into account. This applies especially for
optical cables.
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6. Standardization of plans for underground ducts in tunnels
used jointly for pipelines and telecommunication cables
6.1 Introduction
This paragraph describes the graphic representation of underground ducts
in joint trenches or tunnels.
The graphic representation of underground ducts in joint tunnels is
standardized in several countries, and we shall therefore confine ourselves to a
general presentation in this document. The management of the network concerned is
responsible for updating plans and documents.
Plans must contain all particulars required for the operation,
maintenance and extension of underground ducts, as well as for their protection and
maintenance in working order during repairs.
6.2 Terminology
The term "underground duct" is defined in this document to mean a vector
for the distribution of a fluid, connecting the place of production with the
place of consumption or drainage. It covers pipelines for electricity as well as
telecommunication cables.
6.3 Field of application
Underground duct plans form part of a general information system. These
ducts, whether situated in public or in private areas, constitute public networks
for distribution and drainage and for the protection of the environment.
6.4 Rules applicable to underground duct plans
Scope of information
Underground duct plans must contain, for the benefit of their users,
complete and up-to-date information on:
- the characteristics of the various ducts,
- their location and level,
- their network connections.
Characteristics
Plans must contain all the particulars required for the operation,
maintenance and extension of underground ducts, as well as for their protection and
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AP IX-64-E
maintenance in working order during repairs; they must correspond to the particular
features of each network.
Location and level
It should be possible from the plans to determine the position of ducts
and duct components accurately, to transpose it to other documents and to relate
it unequivocally to official survey points. Measurements must be taken in
conformity with current surveying rules.
Network connections
It should be possible to determine from the plans how ducts are connected
to the network to which they belong. Overall plans or diagrams will often be
required.
6.5 Basic plan
Special rules
The basic plan provides the basic reference for underground duct plans.
Its purpose is to map the layout of areas where ducts are situated.
Contents
The basic plan essentially contains information on:
- fixed points (triangulation points, base points, levelling points);
- property limits, frontiers;
- buildings;
- types and boundaries of crops.
6.6 Duct or network plans
Types of plan
The network plan contains references to all the equipment and telecommand
devices of a distribution or drainage network. Network plans are of the following
types:
- drainage water,
- electricity,
- telecommunication installations,
- district heating,
- gas,
- collective antenna installations,
- water.
Special rules
Every duct or network plan must meet the operational requirements of the
network concerned. The following rules shall apply:
- it must contain all legally required information;
- for ducts, it must give information on their development,
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construction, operation and maintenance;
- it must contain instructions for use in the event of breakdown or
malfunction;
- it must supply operators and third parties with information on the
location and level of ducts.
Contents
A duct plan generally comprises the following data:
Geometric data:
- Duct location
- Duct level
Duct data:
- Fluid transported
- Managing enterprise
- Function
- Type and content
- Profile
- Dimensions
- Material
- Operational condition
- Construction or duct components
- Identification
Auxiliary installation data:
- Protective devices
Scales
The choice of scale depends on the density of ducts. The scale of the
duct plan should correspond, if possible, to that of the basic plan drawn up
in accordance with the survey.
The following scales are recommended: 1:100, 1:200, 1:250 or 1:500
according to the concentration of buildings in the area.
6.7 Preparation of plans
Definition
By preparation of plans and data management the capture, updating,
processing and representation of all data relating to underground ducts is
understood. Any information system for underground ducts can thus be run either
manually or by computer.
Surveys
Principles:
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Whenever ducts are laid or altered, their location and, if necessary,
their level should be surveyed.
If excavations reveal ducts which were hitherto unknown or the location
of which had been uncertain, these ducts must be surveyed. This rule also
applies to ducts located by detection.
Accuracy
Location:
The accuracy of the points used to locate ducts must comply with land
survey rules.
Survey methods
One of the following survey methods must be used:
- polar coordinates,
- orthogonal coordinates,
- distance resection,
- prolongations.
Procedure for preparing plans
- Single-plan system:
The basic plan and duct data should appear on the same medium. Ducts
have to be copied onto the basic plan.
- System of separate superimposable plans:
With this system, each level of data appears on a separate sheet. The
basic plan, duct data and network data can appear as different data levels.
Representation
Ducts are represented graphically by means of conventional signs
described in special standards.
Writing
Writing must be clearly legible and uniform and must be suitable for
reduction and reproduction.
6.8 Use data processing systems
General analysis
A very large volume of data on underground ducts needs to be captured,
stored, updated, processed and reproduced, and they have to be extractable in
different combinations. It is therefore advisable to use computer techniques,
since this is the only way of establishing an integrated system of information on
underground ducts. Such a system can meet various requirements, such as
combining different data levels by the automatic process of separate superimposable
plans; it can also produce extracts (plans, lists etc.) with a differentiated
content.
An underground duct information system has to be designed as a
continuous sequence of operations, including data capture in the field or in the
office, memorizing and processing, and the printouts of plans and lists.
6.9 Keeping plans up to date
Updating
(3208)
CCITT\AP-IX\DOC\064E1.TXS
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Duct plans cannot fulfil their purpose unless they are constantly
updated. The following principles should be observed:
- data on new or modified ducts must be collected and processed as
soon as work is completed;
- basic plans must be kept up to date.
Access to localization data
Localization documents should be available for consultation at any time
between the completion of duct laying and the entry of data in the plan.
6.10 Model plan
Content
The model plan in Annex 3 shows distribution duct pipelines in addition
to transport duct tunnels.
Graphic representation
The tunnels and pipelines should be drawn to scale, corresponding in
width to the internal diameter of the tubes.
Representation of ducts
So many ducts and cables are usually either hung, laid or fixed inside
tunnels that it is not possible to represent each duct individually. They are
therefore represented as cross-sections of the tunnel, which are placed next to
the pipeline or on separate sheets with an indication of their location.
Branches, splices, spurs and other details are entered either on the
plans or in special files. The distribution ducts for the different fluids should
be indicated by conventional signs.
BIBLIOGRAPHY
[1] Recommendation L.1 "Construction, installation and protection of
telecommunication cables in public networks".
(3208)
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