Improving the Performance of Critical Link Analysis in InfoWorks WS

Hydraulic modelling identifies the impact of a failure in a network

Hydraulic modelling identifies the impact of a failure in a network

Within any water supply network there will be links that could be considered critical in a number of ways. It could be the number of customers that would be affected due to a failure, the type of customers affected (such as hospitals, schools, care homes etc.) or perhaps links that would be difficult to repair due to their location. Critical assets can be graded in a number of ways, but it is hydraulic modelling that can identify the hydraulic impact of the failure of a link and therefore the impact on end-users.

Within InfoWorks WS the impact of failures is performed with the Critical Link/Area Analysis tool. The tool closes either a single pipe or an isolation area at a time, runs a simulation and then compares the results with a base simulation. However, because a comparison is required for each simulation the time required to perform critical link/area analysis is greater than the time of the simulations alone. As a result it can be beneficial to reduce the number of simulations that InfoWorks needs to do in order to reduce analysis time.

Three ways of doing this are as follows:

  • Perform the calculation at peak demand for a shorter duration.
  • Use Isolation Areas instead of single pipes – Take for example a network with 1,523 pipes and 545 isolation areas. In this situation closing isolation areas instead of single pipes would lead to a reduction in simulations of 60%.
  • Reduce the number of isolation areas that are analysed – There are some isolation areas, in particular dead end valves and pipes, where the simulation of the closure of a valve is unnecessary as there is no hydraulic impact on other areas.

There is no need to run a simulation for the selected links

These isolation areas could be removed by hand, but this would obviously be a time consuming task. Instead users of InfoWorks WS can use the built in SQL analysis tools and the Skeletoniser Tool to locate and remove a number of isolation areas.

For the same example network mentioned above 148 isolation areas can be identified for removal. This leads to a reduction in simulations of nearly 30% compared to the simulating all isolation areas and around 75% reduction in simulations compared to single pipe analysis. Obviously this will have a substantial impact on the time it takes engineers to perform critical link analysis.

For assistance with the functionality mentioned above, InfoWorks WS users can contact their local support representative for additional guidance. Alternatively dedicated training can be provided on this subject.

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