Tricks of the Trade

What can current applications do?
Several consultants and software vendors do have applications available that assist network designers in the fast generation of cost effective network alternatives. In their simple form, these tools require the following steps by the designer

specify the area that has to be designed,
specify the customer locations,
specify locations for transformer stations,
provide digital base maps, land use data, etc.

The software will than automatically generate the least cost network layout based on context specific rules. Such rules may be:

the network location should be parallel and at a predefined distance to the roadsides,
in some areas digging is not allowed,
soil types, land use and street surfaces have specific associated construction costs,
the crossing of a road may not be allowed,
above ground networks have to consider tree crowns, underground networks similarly have to consider the tree roots. Cutting of branches and roots may be prohibited by environmental regulations,
.......

Of course this type of software can also generate a bill of materials and will produce cost reports.

In some countries/areas, one utility company provides several services, e.g. gas, electricity and CATV. Asthecosts ofdigging area major padofthe construction costs, the integrated design and simultaneous construction of all networks may result in major savings. It also limits the inconvenience for your customers.

The methods used for integrated design usually start with the design of the most restrictive network (often gas). The other utilities will than use the same trenches but their own locations for cabinets and manholes.

What are the benefits?
In order to assess the benefits of the use of O.R. methods, one has to do the design twice: once in the standard (manual) way and once using the combination of GIS and O. R.. As this is costly and time consuming (and a bit of a threat to the manual network designer) there are not very many cases where comparable information is available. The PNEM, one of the major Dutch utilities has gone through this exercise for several residential areas (200 to 1200 houses). The network designs that were generated automatically were 10-1 5% cheaper in construction than the manual designs. The time to do the design with these tools went down to a third of the manual time. The time saved by automated design allows the designer to create and evaluate different alternatives. For example, you can create designs based on different locations for your transformer stations or on a different number of transformer stations.

It should be noted that the savings that can be achieved in this way quite often exceed not just the cost of implementing the O.R. software on top of a GIS, but also the cost of the data acquisition and conversion for the GIS. In other words: these approaches may pay for your GIS in one project.