Building a Modular Interface Between a GM and three (3) Engineering Analysis Packages
Packages
Interfaces have been – or soon will be – written for three specific packages to suit the
requirements of Greenwood (SC) Commissioners of Public Works. The packages are:
- GAS WorkS3, natural gas distribution
- KYPIPE 24, potable water and sewer
- Scott& Scott5, electric distribution
Since we know that this system will need to support several packages, we built it to be a base
for at least these:
- EPANet6, potable water with water quality
- WaterCAD7, potable water with water quality
3Asoftwareproduet andatrademark ofBradley B. Bean,PE, 1517NorthWeberStreet,ColoradoSprings,CO
80907.
4Developed by the Civil Engineering SoftwareCenter,University ofKentucky, CollegeofEngineering, Lexington,
KY40506-0046.
5A product Of Scottk Scott Systems, Inc., 500 Union Street, Suite 745, seattle, WA 981012332.
6Developed by the Risk Reduction Engineering Laboratory, Office of Research and Development, U.S. Environmental Protection Ageney,Cincinnati, OH 42268
7A product and trademark of Haestad Methods,37 Brookside Road, Waterbury, CT 06708.
Stoner SWS-W8, water
Stoner SWS-G9, gas distribution and transmission
Requirements of the AM/FM/GIS System
For export to an external analysis package to be worth the trouble, the network within the
AM/FM/GIS must be correct. Facilities have to be checked for valid network connection as
they are added or changed. Not many AM/FM/GIS systems can do is.
Entity relationships and cardinality must be strictly enforced
The user’s tools should allow a subset of the entire network to be extracted. Although the
entire network may be needed every year or two for a complete end to end study, most of the
time the user wants to make estimates on a limited sub-network.
Finding the “ends” of the sub-network is the key logic required
The sub-network must have valid connections between facilities. If the entity relationships
and cardinality are inherently correct within the AM/FM/GIS, the next requirement is to make
sure that they do not get inadvertently corrupted during export. Here we have the advantage of
a true object-oriented AM/FM/GIS with a true object-oriented database. Since the facilities
are objects with behaviors, we simply have them “report” their connectivity, so there is little
additional code to write or maintain.
Either there must be absolute connection between facilities, or
export must have the ability to re-validate connections during export
Looped flow must be accommodated for piped networks. In the past we could ignore looping
for electrical networks, but that is changing. In an effort to improve power reliability, some
utilities are practicing limited looping. Looping is a challenge to the export process since its
detection is not always easy. If it is not detected, the AMFM7GIS can export duplicates of
nodes and segments. Often the analysis package will detect this, so all you have wasted is
time. Worse is when the package does not detect it and the resulting calculations are wrong
and misleading.
No duplication of a node or segment is permitted in the exported file
The normal output to an analysis package is a node-segment table constructed by the
AM/FM/GIS. The core is a table that maps the facilities in the AIWFIWGIS to their
equivalent in the analysis package. An example of the differences we see are:
- Some AM/FM/GIS facilities can be either a node or a segment in the analysis
package. The assumption in most of these packages is that a human looks at the
paper map sheets, sees a junction and codes it as a pipe fitting because it has no
other significance to the study. But, if you need to know the pressures at that point
or it is an end point of the sub-network being exported, it has to be exported as a
node and not a pipe fitting.
8An abbreviation for Stoner Workstation Serviee- Water by Stoner Associates,Inc.,P O Box 86, Carlisle,PA 17013-0086.
9An abbreviation for Stoner Workstation Serviee- Gas by Stoner Associates,Inc.
- KYPIPE 2 has separate sets of “cards” for each facility catego~.
set must be in precise sequence.
- GAS WorkS has just two “files”, node and pipe
- Some AM/FM/GIS facilities can be either a node or a segment
In addition each
Matching AM/FM/GIS facility types to the categories in the analysis package differs
greatly with each package
We have found the most challenging data format limitations of the analysis systems are in
field size and required data that are not naturally in the AM/FM/GIS. For example,
GASWorkS limits the node name to 10 characters. As noted below, getting a totally unique,
system-wide facility ID within 10 characters is nearly impossible. KYPIPE 2 requires header
data that are meaningless to an AM/FM/GIS.
Finally, the AM/FM/GIS export process must be able to export in DOS, Windows and UNIX
file formats, That is not usually a problem for UNIX-based AM/FM/GIS systems, It maybe
more difficult with DOS or Windows systems exporting to UNIX.
Limits placed on the external analysis system
Most AM/FM/GIS systems keep the network as many short pipe and conductor segments. It
is exported as a very large set of nodes and segments. This can be a problem for some
packages. Some are priced based upon the number of nodes and/or segments they process.
Number of pipes or number of feeders are common terms. Some packages run very slowly
with large numbers of nodes and segments. “Intelligence” within the AM/FM/GIS to join
segments is not dependable. Since network validity has the highest priority, our export design
will not risk loss of topology to reduce the output size.
It must accommodate a large number of segments and nodes I
An AM/FM/GIS with many classes or layers tends to have duplicate IDs or name when
merged into a single extract. So, with thousands of facilities, AMiFM/GIS facility IDs need
to be very long if they are to be unique. We have partly solved this by using “names” that are
really unreadable hexadecimal hash in order to keep the size small. The major disadvantage
is that the IDs are meaningless to the user and they cannot be imported back into the
AM/FM/GIS, as discussed below.
