Page 420 - Shaping smarter and more sustainable cities - Striving for sustainable development goals

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