Network Infrastructure Planning, Operation & Maintenance Guidelines

This section covers the planning, operational and maintenance aspects of a FTTH network infrastructure. Whilst each FTTH network design will differ and operate in different environments and conditions, the planning, operation and maintenance remains a common requirement to all.

During network construction, the builder will need to ensure minimum disruption to the general public and surrounding environment. This will most likely be a requirement through a contract to ensure that installation and build processes cause little or no disturbance within the FTTH area. This can only be achieved by careful planning and execution. This will also drive the need for efficient build methods to be deployed that will ultimately benefit the FTTH business case. Poor planning will have the opposite effect and potentially lead to poor build performance and a failing build programme.

Whilst fibre is a reliable medium with proven reliable service over tens of years, it is still vulnerable to unexpected breakdown that will require mobilisation and rapid and efficient repair. During such times immediate access to the networks records by those tasked with repair is essential. It is vital from the onset of the network build that records and documentation are collated and centralised to support all subsequent network analysis.

Maintenance procedures must be planned in advance and contractual arrangement put in place to ensure the appropriate manpower is on hand when needed.

1 Network Infrastructure Network Build Planning Guidelines

Site Control and Installation Operation Planning.
Work with underground duct systems or installations on sideways or poles, will require careful planning and in many cases cause disruption to traffic. Liaison with local authorities will be required and suitable controls put in place. The following points briefly list the main installation considerations that need to be taken into account when embarking upon a duct type installation:

A working familiarity with underground or aerial duct and cable systems, practices and working operations is essential.
Careful planning of the installation will lead to an efficient and safe operation. Liaison with the Local Authorities prior to installation is recommended, where appropriate.
A full appreciation of nearby Utility Services must be obtained both from the local authorities and by "on site" confirmation using suitable detection equipment.

Proper safety zones using marker cones and traffic signals should be organised. Disruption of traffic should be coordinated with local officials.
All manholes and cable chambers should be identified and those intended for access should be tested for flammable and toxic gases before entry.
For confined spaces, full air and oxygen tests should be carried out before entry and forced ventilation provided as necessary. Whilst working underground, all personnel must have continuous monitoring gas warning equipment in operation at all times - flammable, toxic, carbon dioxide and oxygen levels.
In cases where flammable gas is detected, the local Fire Service should be contacted immediately.
All existing electrical cables should be inspected for any possibility of damage and exposed conductors.

A full survey of the complete underground duct system or aerial plant should be carried out prior to installation.
Manhole and cable chambers with excess levels of water should be pumped out.
Ducts should be checked for damage and potential obstructions. Rodding of the duct sections using a test mandrel or brush is recommended prior to installation.
Manholes should be checked to ensure suitable space for coiling slack cables, provision of cable supports and space for mounting Splice Joint Closures.
A plan should be established to optimally position the cable payoff, mid point fleeting and cable takeup/winching equipment. The same also applies if the cables are to be blown into the duct which requires Blowing Head and Compressor Equipment. Allowances for elevation changes should be taken into account accordingly.
Fleeting the cable at mid sections using a Figure of 8 technique can greatly increase the pulled installation section distance using long cable lengths. However careful planning must ensure these locations are suitable for cable fleeting.
The duct or inner duct manufacturer should be contacted for established cable installation guidelines.
Ribbed, corrugated ducts and ducts with a low friction liner are designed to reduce cable/duct friction during installation. Smooth non lined ducts may require a suitable compatible cable lubricant.
Pulling grips are used to attach the pulling rope to the end of the cable. These are often mesh/weave based or mechanically attach to the cable end minimising the diameter and thus space of duct used. A "fused swivel" device should also be applied between the cable pulling grip and pulling rope.
The swivels are designed to release any pulling generated torque and thus protect the cable. A mechanical breakaway fuse protects the cable from excess pulling forces by breaking a "sacrificial" shear pin. Pins are available in different tensile values.
A Pulling Winch with a suitable capacity should be used. These should be fitted with a dynamometer to monitor tension during pulling.
Sheaves, capstans and quadrant blocks should be used to guide the cable under tension from the payoff, to and from the duct entry and to the take-up equipment to ensure that the cable’s minimum bend diameter is maintained.
Communication radios, mobile phones or similar should be available at all locations in the operation.
Use of mid point or assist winches may be recommended in cases where the cable tensile load is approaching its limit and could expedite a longer pull section.
Cable Payoff Device: a reel or drum trailer is recommended.
For aerial applications appropriate equipment such as bucket trucks should be foreseen. Specific safety instructions for working in altitudes need to be respected. Specific hardware is available for cable and closure fixture.

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