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Next: CNTPOST: A Macro for Optimal Up: EMME/2 News 10 October 1990 Previous: Three Useful Macros

VALIDNET: A Network Validation Macro

(contributed by Denis Lebeuf, INRO Consultants)

Network validation is always a tedious and time consuming task. Not too long ago, the main tools available to accomplish this task were a pile of listings and luck. The advent of interactive graphics drastically reduced the amount of data to be scanned (an image is worth a thousand words, it is said) and thus also reduced the importance of the luck factor. Nevertheless, a more systematic approach is needed, if one wants to rely on the results from analysis carried out with these network data. We present here an EMME/2 macro which is a step toward such a systematic network validation method.

The VALIDNET macro uses mainly the network calculator (module 2.41) to perform a set of up to nine tests that detect all the occurrences of some potentially pathological conditions. We say "potentially pathological" in the sense that all the cases detected by the macro are not errors per se, but surely likely candidates. The macro assumes that the base network is syntactically correct (otherwise EMME/2 would not have accepted it) and draws the attention to some potentially questionable topological aspect:

Here are the nine tests that can be performed by VALIDNET:

The tests to be performed by VALIDNET can be specified by using the corresponding keywords as parameters to the macro. If no keywords are specified, all tests will be performed.

Each node or link that does not pass one of the tests is marked with a test specific value in user data UL3. They can then be exhaustively listed using a punch or report format, or can be viewed and quickly located on network plots by using the test specific marking as a color index value. For each test, the total number of instances found is also written in a summary file and kept in a scalar matrix.

The network validation process cannot be fully automated and we emphasize again that the VALIDNET macro uses a most likely candidate method. All data items identified by the macro must be examined on a case by case basis by someone familiar with the network to determine if it is a wanted feature or a coding error. The VALIDNET macro is far from doing exhaustive testing, but constitutes a very fast and efficient tool to do a first level validation.


next up previous
Next: CNTPOST: A Macro for Optimal Up: EMME/2 News 10 October 1990 Previous: Three Useful Macros


Heinz Spiess, EMME/2 Support Center, Thu Jun 6 14:22:53 MET DST 1996