Apart from availability, other infrastructure service attributes which could be
measured include, for example, water quality, road safety, passenger comfort,
electricity frequency fluctuations, time taken to address a complaint, etc. These
would measure quality of service.
Cost and efficiency indicators can, from (i) the consumer and (ii) the service
providers point of view, determine the cost of infrastructure services. For users, the
costs are measured in money units per units of service (e.g Euros X/kWh, $/m
3 , etc.),
while the inverse units are applicable to measure efficiency by the service providers
(Z m
3 /Euro, Y kWh/$, etc.). In a similar reasoning, the service provider might also
wish to measure his efficiency in terms of service provision per unit of energy input.
For example, a water supply provider may also measure how many cubic metres of
water are produced per kilowatt hour of energy used at each treatment plant.
It will be seen later (Chaps. 8 and 17) that providing infrastructure services is also
accompanied by other positive or negative effects (gas emissions, accidents, beautiful scenery, etc.) called externalities. Thus, externality indicators may be
established to indicate the degree or extent of such side effects for each infrastructure
sector or service.
6.5 Elements of System Dynamics Modelling
System dynamics modelling needs explicit appreciation of two kinds of flows:
(1) physical flows which are maintained and (2) information flows which are not
preserved. Increases take place in both types of flows, which have different properties. Their accumulations are also different from each other.
6.5.1 Physical flows
Physical flows resemble water flow in pipes, and while accumulations resemble
accumulated water in the storage reservoirs at various nodes of the pipeline. The
volume of accumulated water in a reservoir, of course, depends on the inflow and
outflow rates of water from the reservoir. Therefore, the flow rates automatically
govern the accumulated water.
Physical instruments determine only the average flow rate values over a period of
time, but the instantaneous flow rate values are, rarely, really measurable. The
volume accumulated is, of course, quantifiable at any point of time. Instantaneous
flow rate values are usually functions of the accumulations, and are ruled by certain
laws. While natural laws rule in physical systems, social systems are governed by
laws representing the policies and controls which may or may not have been
established explicitly, but which, nonetheless, dictate individual decisions now
and then.
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measured include, for example, water quality, road safety, passenger comfort,
electricity frequency fluctuations, time taken to address a complaint, etc. These
would measure quality of service.
Cost and efficiency indicators can, from (i) the consumer and (ii) the service
providers point of view, determine the cost of infrastructure services. For users, the
costs are measured in money units per units of service (e.g Euros X/kWh, $/m
3 , etc.),
while the inverse units are applicable to measure efficiency by the service providers
(Z m
3 /Euro, Y kWh/$, etc.). In a similar reasoning, the service provider might also
wish to measure his efficiency in terms of service provision per unit of energy input.
For example, a water supply provider may also measure how many cubic metres of
water are produced per kilowatt hour of energy used at each treatment plant.
It will be seen later (Chaps. 8 and 17) that providing infrastructure services is also
accompanied by other positive or negative effects (gas emissions, accidents, beautiful scenery, etc.) called externalities. Thus, externality indicators may be
established to indicate the degree or extent of such side effects for each infrastructure
sector or service.
6.5 Elements of System Dynamics Modelling
System dynamics modelling needs explicit appreciation of two kinds of flows:
(1) physical flows which are maintained and (2) information flows which are not
preserved. Increases take place in both types of flows, which have different properties. Their accumulations are also different from each other.
6.5.1 Physical flows
Physical flows resemble water flow in pipes, and while accumulations resemble
accumulated water in the storage reservoirs at various nodes of the pipeline. The
volume of accumulated water in a reservoir, of course, depends on the inflow and
outflow rates of water from the reservoir. Therefore, the flow rates automatically
govern the accumulated water.
Physical instruments determine only the average flow rate values over a period of
time, but the instantaneous flow rate values are, rarely, really measurable. The
volume accumulated is, of course, quantifiable at any point of time. Instantaneous
flow rate values are usually functions of the accumulations, and are ruled by certain
laws. While natural laws rule in physical systems, social systems are governed by
laws representing the policies and controls which may or may not have been
established explicitly, but which, nonetheless, dictate individual decisions now
and then.
174
6 Infrastructure as a System