Modelling Firefighters - Using Your Network Model to Keep People Safe
Annual Conference
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The Fire Code (SNZ PAS 4509:2008) has long been the go-to document for determining fire flow requirements in urban water networks. However, the focus of the Fire Code itself is on individual buildings - the puzzle for network analysts has always been how to run a system-wide analysis with consideration of individual buildings.
In particular, the Fire Code talks about the number of hydrants within a certain distance of the building. Interpreted literally this means you can use any hydrant within a certain radius, and this is easily done with simple GIS tools. However, reality in the field can look very different - the whole purpose of having a hydrant nearby is to ensure firefighters can plug one end of a fire hose into the network and get to the fire with the other end.
As a first responding appliance to any structure fire there are a number of considerations the officers need to think about. On the way to a call information may be relayed via Firecom, including, location of fire hydrants in the area of the address and if there are any recorded hazards as part of the risk identification carried out at the address particularly if it is a commercial or industrial building.
Several considerations and risks need to be considered by the Fire Emergency officer; number of persons reported, building size, fuel loading, neighboring buildings, access, and location of hydrants and available water supplies.
To determine where people are genuinely at risk, Wellington Water has taken advantage of their consultants’ panel to draw on the expertise of both Stantec and WSP Opus to create a methodology for fire hazard assessment for every property in the region. This incorporates both hydraulic model outputs and the nationally consistent OpenStreetMap roads dataset into a simple online tool to determine the most likely access route for firefighters to any building, and the likely available fire flow from hydrants they can actually use.
A second aspect of ongoing frustration to water network modellers is that the fire code is based around simultaneous use of multiple hydrants to obtain the required flow. Modelling software can give you accurate predictions of how much water is available at a single hydrant, but flow from multiple hydrants requires manual setup and analysis – not practical for every building in a city. A statistics-based analysis has been developed to determine the combined output of a group of hydrants from the single-hydrant flows which are readily available from an InfoWorks model. This analysis provides an estimate of the total available hydrant flow for any given set of hydrants.
With knowledge of which hydrants can be used and how much water is available from these hydrants, Wellington Water is now able to estimate the level of fire coverage for every property in the region.
This paper will explain how Fire and Emergency NZ (FENZ) manage risk when fighting fires, how this relates to the current CoP, and how modelling and GIS tools have been developed to better inform FENZ when fighting fires.