Right-of-way planning considerations

Edit online

The introduction of optical fiber into the data communications environment has provided extended distance connections. This sometimes results in a requirement to enter and exit other public and private rights-of-way not under your direct control. This added requirement to installation planning may be a new consideration for many customers. The extended links offered today require dedicated pairs of fiber cable from one end of the link to the other. These dedicated fibers are sometimes referred to as dark fiber in that there are no active components on the link other than the customer's equipment at each end. The requirement for dark fiber is new not only for the customer but also, in many cases, for the traditional providers of services between facilities. Therefore, it is important to use early planning and negotiation for rights-of-way for dark fiber to install extended distance links on schedule.

Because every installation has unique characteristics, it is not possible to provide one approach to meet all planning considerations. The following factors should be considered when planning for any right-of-way requirements:
  • Fiber specifications (See Specifications).
  • Growth and migration plans
  • Numbers of fibers to include current, growth, and service spares.
    As a general rule, the total number of optical fibers installed should be equal to the sum of the following:
    Requirement Sum
    Total number of fiber strands required immediately = ______
    Plus 10% (for spares) = ______
    Plus two terminated pairs (if spares are not terminated) = ______
    Plus 30% of the number required immediately (for future growth)    
         
    Total fiber strands required = ______

    Be prepared to increase the total optical fiber required if the environment seems to have a high chance of damage. Once a trunk cable is terminated and installed, opportunities for damage are substantially reduced.

  • Physical routing considerations include
    • Redundancy and alternate cable installation

      Additional optical fiber may be needed (beyond that needed to meet requirements, spares, and projected growth). Because optical fiber allows for increased distances, all external cable routings should be reviewed for tolerance to interruption. If quick availability is critical, redundant cables and trunks in several locations may minimize system downtime during restoration activity.

      Major factors to be considered in this decision should include
      • Security from physical damage
      • Disaster recovery
      • Cost and time to repair (as opposed to initial installation costs)
      • Physical limitations and risks of the proposed right-of-way route
      • Post Telegraph Telephone (PTT, the National Post and Telecommunication Authority), contractor, and vendor capabilities
      • Serviceability – ease of access to the installed cable and trunk for inspection, repair, and restoration
      • Environmental factors affecting long-term reliability. Adverse forces (such as extreme temperatures, precipitation, dust, chemicals, nuclear radiation, and construction activities) may degrade the installed cable.
    • Use new as opposed to existing facilities
    • Physical installation considerations
    • Reliability
    • Common carrier or governmental regulatory constraints
    • Tariffs
    • Incidental considerations (for example, removal and replacement of walkways and streets, relandscaping, and renegotiation of other utility rights-of-way).
  • Building entry and exit
    • Connectors and adapters
    • Physical-contact connectors (SC, ST, or FC/PC) are recommended for trunk termination. Duplex-to-ST or Duplex-to-FC/PC adapters are recommended in distribution panels.
    • Selection of distribution panels
    • Interior building cable routing plans
    • Routing types (such as trays, conduit, and raceways)
    • Building and wiring codes (for example, National Fire Protection Association Codes (NFPA), National Electrical Codes (NECs), and local codes)
    • Cable densities, strain relief, bend radius control, splices, and considerations about storage of cable.
  • Contractor selection and contract agreements.
  • Labeling
    • Panel labeled with laser warning as required
    • Cable routing control
  • Record keeping
    • Installed cable specification
    • Cables routing control
    • Serviceability
    • Warranty.
  • Costs

    Installation costs as opposed to component costs must be balanced to accommodate growth and migration.

  • Facility security requirements (such as lockable panels, lockable and controllable closets, security along rights-of-way, inspection schedules).
  • Simultaneous use of optical fiber for video and voice is not an option for most data communications products at this time due to problems in multiplexing.
  • Compatibility of all components is essential for reliability, serviceability, and aesthetics, especially in installations where optical fiber already exists.

Some skills required to install optical fiber components are different from those required to install copper. Contractors employed to install these components should have appropriate training and experience. This is especially important for optical fiber cable termination and splicing.

Correct handling procedures for optical fiber cable are identified by the manufacturer and should always be followed during installation. These specifications include minimum bend radius, maximum pulling tension, pulling lubricants allowed, and recommended pull-in procedure. The cable manufacturer should also recommend the correct procedures for cable sheath removal, stripping, and strain relief. The manufacturers of various types of connectors and splices ship instructions for the correct installation of their products (written for trained personnel).