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3.3  Lifecycle and obsolescence


            3.3.1   Life of built infrastructures and provision for replacement
            The built infrastructure may be considered to have a life ranging from 5‐100 years. A common
            infrastructure therefore needs to be accessible to allow service providers to carry out work including
            new service provision, upgrade and replacement.
            Examples of typical life times are: ICT (5 years), rail track and signalling (15‐20 years, [b‐8]), road
            surface  (20  years,  [b‐8]),  electricity  (20  years),  data  centre  20  years  [b‐8],  storm  water  run‐off
            (30 years), water pipeline (100 years [b‐8]), and sewerage (100 years [b‐8]).

            3.3.2   The built‐infrastructure – radical changes can be envisaged
            Infrastructure, such as a utility tunnel, could have a lifetime of 100 years or more. The speed of
            technological advances especially in the ICT sector could render some of the city infrastructure
            obsolete  within  10  years.  Examples  include:  self‐drive  vehicles,  tracked  buses  superseding  rail,
            delivery  services  by  autonomous  vehicles  including  drones,  solid  refuse  collection  using
            underground ducting powered by suction of air. An issue for planners to consider is to what extent
            the infrastructure should be future‐proofed.
            Provision for additional storm water run‐off is a major consideration for some cities as the impact
            of climate change is factored in. One example is G‐Cans Project, or the Metropolitan Area Outer
            Underground Discharge Channel, which is the world's largest underground flood water diversion
            facility. It is located between Showa in Tokyo and Kasukabe in Saitama prefecture, on the outskirts
            of the city of Tokyo in the Greater Tokyo Area, Japan [b‐13]. Utility tunnels may be an essential part
            of a SSC's storm water run‐off plan.

            3.3.3   Powering the sensor layer network

            Powering the sensor layer network is an important lifecycle consideration. Visiting remote locations
            to replace batteries in wireless sensors is an expensive service maintenance consideration. A battery
            life of less than 10 years can destroy a remote sensor business proposition. Wireline options should
            therefore be considered as an alternative to wireless devices.



             Box 1

             Example: Power over Ethernet [b‐14] can power sensors or actuators in a sensor layer network without
             recourse to batteries or a separate electricity supply from the network connection.




             Box 2
             Example: The HomePlug Powerline Alliance (HPPA) has developed standards and technology enabling
             devices to communicate with each other, and the Internet, over existing home electrical wiring. Power and
             communications may therefore be combined over a common mains facility to sensors or actuators on the
             periphery.












            410                                                      ITU‐T's Technical Reports and Specifications
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