Tricks of the Trade
Network construction & what O. R. can do for you
The design of a network in a newly built area starts with an inventory of relevant
data. Supposedly, the number and the location of the future customers are known, either from a
layout plan or from field surveys of customers-to-be. Generally, the network will be positioned
alongside the roads and in urban areas underneath the curbs. Only a limited number of
locations are suitable for the location of equipment such as high voltage transformers and gas
stations. These stations have to be connected to the existing mains network. Each location has
an associated cost of linking it to the mains network. Also, the location itself has costs
associated to it. The costs per unit length of network construction depend on the type of cable
but also on the method of construction. Overhead networks have a different price structure from
underground networks where the costs of digging depend on issues like soil type, type of
pavement or the availability of conduits with free space. Road crossings are usually costly, so
limiting the number of road crossings can be a design issue.
With respect to other issues, no precise knowledge is available and planning and design will be
based on assumptions. For example: what percentage of households will subscribe to the
services at a later point in time? Does that require additional network capacity? In the past many
utilities had a local monopoly and could build over-dimensioned networks. In today’s competitive
world this is no longer an alternative. In fact, the opposite is the case: what use can be made of
the over-dimensioned networks of the past? Is a network upgrade really necessary or does the
existing network have sufficient capacity?
There are major differences in the design details (and consequently, in the definition of the
Operations Research problem that has to be solved) between countries. In large parts of North
America the electrical and telephone networks are above the ground. This gives a great deal of
freedom of choice for the network location. In urban areas overhead networks may not be an
option and a system of conduits may have to be designed. In areas that do not have a rocky soil
(such as all of the Netherlands) the preferred way of building the network can be to dig trenches
and put the network in the ground without protection.
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