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TO REDUCE THE OVERSUPPLY AND MAINTENANCE COST OF FIRE HYDRANTS USING QUANTUM GIS By Abbas Abdul Wahab Federal Department of Town and Country Planning Peninsular Malaysia abbas@townplan.gov.my This paper acknowledges and appreciates the contributions made by Mohd. Fadzlan Mhd. Sa'ad, Federal Department of Town and Country Planning, Peninsular Malaysia in joint efforts to promote the use of Quantum GIS (QGIS) as a mapping as well as an analytical tool. ABSTRACT This study is a simple GIS analytical exercise to see how clever use of GIS planning can help save much public money and help reduce annual maintenance cost for the fire department by the prevention of unnecessary oversupply of hydrants to an area. The study is very effective and only utilizes the buffer technique, simple SQL queries and basic arithmetics to come up with its conclusion. INTRODUCTION Proper planning of public infrastructure means prudent use of public money, be it for the provision or maintenance of those assets. It also means that more public are accessible to such public infrastructure since distribution is optimal. With GIS, it is possible to guide planning and ensure that the distribution of such resources are soundly carried out and not exhaust the public coffer. But how best can one go about it? Quantum GIS (QGIS) has the capability to be used for mapping and analaytical purpose. In order to further promote the potentials and capability of QGIS as a userfriendly GIS for analytical purposes, a study was carried out to see if it is possible to use this free GIS and identify whether an area was over or under supplied in the provision of fire hydrants and to determine whether maintenance cost could have been reduced through GIS planning for fire hydrants. CASE STUDY The study area involved a section of Air Keroh, Malacca where existing hydrants are found. Google Hybrid was imported and used as the background to help orientate and give the user a better visual prespective of the study area as shown below:
However, for the purpose of this paper, it was removed to make it easier to show the study outputs.
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Firstly, the existing hydrant layer was activated as shown below:
Reference to the fire and safety department showed there that the minimum distance between fire hydrants varies between 50-300m. Many technical issues affect this distance such as water pressure of an area concerned. But the greater the buffer distance, the greater, the chances of overlapping buffers to occur so for the purpose of this study, a buffer radius of 50m was used. Using the geoprocessing tool 'Buffer', a catchment area of radius 50m for each hydrant was applied as shown below:
Ideally, each buffer catchment area should only contain one hydrant so an area where this occurs implies that the distribution of hydrants there was properly planned and not wasteful. For the study area, there was a need to determine the number of buffer catchment areas that contain more than one hydrant, if any. Here, it was necessary to come up with an attribute table output that could identify the number of hydrants per buffer. To do that, the analysis tool 'Points in Polygon' was used to merge the hydrant and the buffer catchment area layers as shown below:
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The result after running that module is shown below:
Next, the Query Builder was used to determine if buffers with more than 1 hydrants exist. The SQL clause used was “PNTCNT>1� and a test revealed 421 matching cases as shown below:
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The result after running the SQL query is shown as below:
A macro view of the study area found that the distribution of such cases is not specific to any area but randomly throughout the study area as shown below:
ITEM
Distribution of hydrants by buffer type UNIT
Buffer with 2 hydrants
323 buffers x 2 = 646 hydrants
Buffer with 3 hydrants
71 buffers x 3 = 213 hydrants
Buffer with 4 hydrants
27 buffers x 4 = 108 hydrants
421 buffers Oversupplied hydrants
967 hydrants 967 - 421 =546 hydrants
Separate SQL clause were used to detemine the number of hydrants per buffer e.g. “PNTCNT=2”, “PNTCNT=3” and “PNTCNT=4”. The results were summed together to calculate the number of hydrants affected within those buffer catchment areas. Lastly, since a ratio of 1 hydrant is required per buffer catchment area, 421 hydrants were deducted from that 976 quantum to determine the number of oversupplied hydrants.
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In terms of cost savings, for the purpose of this exercise it is assumed that the annual maintenance of a hydrant is RM1,000. Thus, using simple arithemetic, the cost savings for this study area was calculated as shown below: COST SAVINGS ITEM
SAVING
Annual maintenance of 1 hydrant
RM 1,000
Annual maintenance of oversupplied 546 hydrants
RM 1,000 x 546 = RM546,000
RESULT 1. Out of a total of 1,236 hydrants, 546 hydrants were oversupplied to the study area. 2. That amount of oversupplied hydrants equate to an annual cost savings of RM546,000 which could have benefitted other critical areas yet to be provided with hydrants e.g. key hazardous industrial areas. CONCLUSION 1. GIS analysis can help save public money by public utilities making more effective use of GIS; 2. Clever use of GIS planning helps to distribute resources more evenly and reduce annual maintenance cost; 3. GIS is a double edge sword but used wisely, can be a great help to the local community in terms of a better distribution of public infrastructure.