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Abstract
The foundation of traffic safety work is information. The primary task is to establish a traffic accident database and than to maintain and analyse the same. The use of computers makes this effort more comprehensive and productive. Till now the data bases are in the form of linear record file system, nicely helpful in placing the analysed information only in tabular forms. For a better understanding and good decision-making visibility was not apparent in the databases and in it’s outcome. The GIS (Geographical Information System) a graphical information system that supports display and analysis of spatial data has revolutionised making and use of maps where as some times back it was a tedious exercise. The powerful aspect of GIS is its flexibility in modelling special objects to suit particular application requirement. It helps in understanding the characterstics of concerned area in aggregate by taking care of accident data and by linking to geographical features. Further accidents do not occur uniformly and their occurrence may be due to the number of limitations existing in those areas. These accidents could be studied and analysed to identify in some form of patterns through GIS. In this paper a conceptual effort has been made to identify the problem-zones. The complete zone under consideration can be an attention-requiring area or a subset of the same. To observe the patterns of accidents, it is necessary to mark the location of accidents in area on the map and thereafter, define the zones in terms of problems and resources. The analysed information would be useful in adopting improvement measures for finally selected zones.
Introduction
Road accidents are one of the most important problems being faced by modern societies. The deaths of persons and serious economic loss caused by road accident demand a continuous attention in accordance with the spectacular growth in road transportation. The fact shows that India’s motor vehicle population is hardly 1 % of the world while its share in world road traffic accident is nearly 6%. About 61% accidents occur due to heavy vehicles in the country. The national highway accounts for 25% accidents, 34% of deaths and 28% of injuries on road. Likewise more and more statistics is available with different perspectives. The accident problem perceptions are mostly handled out to bring the conclusion based on data – primarily the FIR data from police departments. It requires consistency and accuracy in location reference and simultaneous consideration of FIR Data, Roadway Inventory Data and Work-zones. Analysis based on these different streams of data in-relation having impact and cause of dependency on each other parameters requires patience and skill. The different source makes the process complex though preference is for general, uniformed aggregate approach i.e. a macro level approach, which includes micro analysis as well. To deal with these limitations, to make the actions visible, to identify accidents patterns, GIS is a gateway to move ahead.
GIS Potentiality
GIS is Geographical Information System that supports the display and analysis of spatial data. GIS has its strength in providing capabilities to model the physical proximity of spatial features. The powerful aspect of GIS is the flexibility in modeling spatial objects to suit particular application requirement. GIS provide capability to store and maintain large data sets. GIS provides relational link between different streams of accident data - FIR Data, Inventory Data etc. It provides facilities to understand one to many, many to many and many to one relation-ship, which exists in spatial data. An expert may put his concentration on an intersection or a culvert or a type of accident or on a combination of parameters. The GIS provides new capabilities of data comparison and analysis that were not available in non-GIS linear reference system. GIS enables the safety experts to compare accidents along a road way segment with land use and zoning-data or population and other demographic data to gain a better understanding of the relationship of crash incidents or the zone-data could be integrated with accidents records to provide a true picture. Visual ability of GIS permits the mapping of FIR data, Inventory data and geometry data. Maps can be created to show the accidents of several targets groups (pedestrian, cyclist, intersection etc.) but also of various subgroups of victims or accident circumstances. The mapping provides beside a spot / intersection identification a way to establish zones and understanding of accident patterns. Patterns may cluster in linear or circular form or in other shapes.
The authorities are always on lookout to make roadways safer either by improving engineering measurements or by traffic monitoring. However, at times it is not advice able or feasible to implement safety improvement ideas in the whole city. The reason accidents do not occur uniformly, characteristics of roadways vary significantly. The reason may also be the geography of area, demography of area, funds allocation or combination of these. Safety improvement programs are required to be applied first in those areas (or zones) where the accident occurrence is high and land area is small. In this connection it is necessary to define zones.
What is Zoning?
The zoning process provides a systematic method for identifying accidents prone locations for safety improvement programs in cost-effective manner. Zoning identifies a subset of area having high number of accidents with respect to as little land area as possible. The motive is to gain maximum possible efficiency. The efficiency can be expressed as a ratio -
When the ratio is in form –> “ % of accident problem addressed > = % of land area covered” than zoning will yield a meaningful results.
The establishing of zones encourage safety programs where improvement measure can be incorporate where otherwise it is not feasible to apply safety improvement measures citywide. Zoning brings the following profits:
Zone Preparation
Zoning is quite simple and it includes the following steps:
First of all pick up the accident problem e.g. more number of crashes involving heavy vehicles, two wheelers or pedestrian, high dose of drugs or alcohol that effect driving or stretch forcing monotones driving etc. This further need detailed accident data from FIR, Road Inventory and other sources. The data should be complete and sufficient enough to produce stable maps. At least three to four years data should made be available for the purpose because more data shows more better clusters of accident locations helpful in establishing zones.
Second the available data of accidents can be mapped manually or by a computerised mapping system often called as Geographic Information System (GIS). Computerised mapping is obviously more efficient in making the correct location of each event.
The GIS permits the analysis of full range of variables appearing in FIR Data, Road Inventory Data and other streams of data. It establishes a link among different streams of data pertaining to accident. These data records are to be entered in computer with the location information. There after the maps can be created to show the crashes not only of target groups but also of various subgroups e.g. early morning accidents or accidents at intersections. Separate maps are needed to display different subsets of data or different colour /symbol scheme could be adopted to show type of accidents.
Defining Zones
A visual examination of map will show whether accident crashes of interest clusters in some way in an area of city. If the clustering is not apparent i.e. map shows that target-groups events are randomly spreaded than problem may not be zoneable i.e. percentage of addressable problem is less than the percentage of land area covered. On the other hand if clustering is apparent with some dispersion it will show a some kind of pattern.
To identify zones it is necessary to provide some qualification to the concern zone. Some initial shape or pattern should be selected for zones and also fix some number of accidents that must fall in that area i.e. defined as zone. In establishing the pattern search should be made first for circular zones than for linear zones there after other patterns.
Search for circular zones
Experts says that accidents occur more frequently in a radius around some place e.g. around some work place, residential place, hospitals, schools or intersection. For study purpose accidents occurring within a radius of one or two kilometer will be a manageable area where safety improvements programs can be initiated. The circular zone must be characterised by minimum number of accidents; this rating will make it enable a deserving order zone to process safety improvement programs. The rate depends upon the size of sample of number of reported accidents available, how many accidents cluster and overall land area of concern covered. The number of accidents in a zone is simply an indicator where as clustering of accidents is more of high concern.
Search for linear zones
The safety improvements put their concentration along a road segment where accidents occur more frequently, which may be a part of circular zone. The GIS helps out in displaying those locations both on single strip of roadway as well as in circular zone. A manageable length for road segment and number of minimum accidents over a period of time must be allocated to make that linear zone ordered linear zone for safety improvement programs.
Final pattern of zones
With the aid of GIS map shows different pattern of interest where these pattern may be contiguous or scattered. When the contiguous zones overlap each other they are of more importance and demand high concentration. It may be possible when two circular zones having high number of accidents at periphery they can be clubbed with other zones and a new pattern can be created. It may be better to add or delete few locations to keep neighborhood zone intact. Boundaries may be revised to a square or rectangular area to generate better impact of safety improvement programs.
Ordering of zones
After establishing of circular, linear zones restructure the same if required to fall in some order. Finally for all the zones percentage of accident problem addressed and land area is required to be calculated in order to program coverage efficiency. If the ratio of percent of problem addressed to the percent of land area covered in the zone is much less than the defined zone may need to be re-examined. If efficiency ratio is high e.g. 60% of accidents of interest in 20% of concerned, land area will definitely demand for safety improvement measures. If the ratio is not going to be high that area may be studied as a non-zoneable area.
Zones Utilisation
Conclusion
The zoning application is not limited to one particular problem. In reality any highway safety problem, which can be described by the geographic location of occurrence will be a good exercise for zoning. The above strategy could be applied to all type of vehicle crashes, roadway maintenance activities and pedestrian safety etc. In fact zoning can potentially be applied to any highway problem that has a mappable target measure and could benefit from more efficient safety improvement program deployment.
GIS as an aid to identify accidents patterns
Alind Saxena, Ganesh Babu
Scientist(Environment & Road Traffic Safety, CRRI)
alind@cscrri.ren.nic.in
R. K. Bajpai
Head (Envirnoment & Road Traffic Safety, CRRI)
Dr. S. M. Sarin
Director (Road Safety) IRTE Retd. Scientist (Director -Grade) CRRI
Alind Saxena, Ganesh Babu
Scientist(Environment & Road Traffic Safety, CRRI)
alind@cscrri.ren.nic.in
R. K. Bajpai
Head (Envirnoment & Road Traffic Safety, CRRI)
Dr. S. M. Sarin
Director (Road Safety) IRTE Retd. Scientist (Director -Grade) CRRI
Abstract
The foundation of traffic safety work is information. The primary task is to establish a traffic accident database and than to maintain and analyse the same. The use of computers makes this effort more comprehensive and productive. Till now the data bases are in the form of linear record file system, nicely helpful in placing the analysed information only in tabular forms. For a better understanding and good decision-making visibility was not apparent in the databases and in it’s outcome. The GIS (Geographical Information System) a graphical information system that supports display and analysis of spatial data has revolutionised making and use of maps where as some times back it was a tedious exercise. The powerful aspect of GIS is its flexibility in modelling special objects to suit particular application requirement. It helps in understanding the characterstics of concerned area in aggregate by taking care of accident data and by linking to geographical features. Further accidents do not occur uniformly and their occurrence may be due to the number of limitations existing in those areas. These accidents could be studied and analysed to identify in some form of patterns through GIS. In this paper a conceptual effort has been made to identify the problem-zones. The complete zone under consideration can be an attention-requiring area or a subset of the same. To observe the patterns of accidents, it is necessary to mark the location of accidents in area on the map and thereafter, define the zones in terms of problems and resources. The analysed information would be useful in adopting improvement measures for finally selected zones.
Introduction
Road accidents are one of the most important problems being faced by modern societies. The deaths of persons and serious economic loss caused by road accident demand a continuous attention in accordance with the spectacular growth in road transportation. The fact shows that India’s motor vehicle population is hardly 1 % of the world while its share in world road traffic accident is nearly 6%. About 61% accidents occur due to heavy vehicles in the country. The national highway accounts for 25% accidents, 34% of deaths and 28% of injuries on road. Likewise more and more statistics is available with different perspectives. The accident problem perceptions are mostly handled out to bring the conclusion based on data – primarily the FIR data from police departments. It requires consistency and accuracy in location reference and simultaneous consideration of FIR Data, Roadway Inventory Data and Work-zones. Analysis based on these different streams of data in-relation having impact and cause of dependency on each other parameters requires patience and skill. The different source makes the process complex though preference is for general, uniformed aggregate approach i.e. a macro level approach, which includes micro analysis as well. To deal with these limitations, to make the actions visible, to identify accidents patterns, GIS is a gateway to move ahead.
GIS Potentiality
GIS is Geographical Information System that supports the display and analysis of spatial data. GIS has its strength in providing capabilities to model the physical proximity of spatial features. The powerful aspect of GIS is the flexibility in modeling spatial objects to suit particular application requirement. GIS provide capability to store and maintain large data sets. GIS provides relational link between different streams of accident data - FIR Data, Inventory Data etc. It provides facilities to understand one to many, many to many and many to one relation-ship, which exists in spatial data. An expert may put his concentration on an intersection or a culvert or a type of accident or on a combination of parameters. The GIS provides new capabilities of data comparison and analysis that were not available in non-GIS linear reference system. GIS enables the safety experts to compare accidents along a road way segment with land use and zoning-data or population and other demographic data to gain a better understanding of the relationship of crash incidents or the zone-data could be integrated with accidents records to provide a true picture. Visual ability of GIS permits the mapping of FIR data, Inventory data and geometry data. Maps can be created to show the accidents of several targets groups (pedestrian, cyclist, intersection etc.) but also of various subgroups of victims or accident circumstances. The mapping provides beside a spot / intersection identification a way to establish zones and understanding of accident patterns. Patterns may cluster in linear or circular form or in other shapes.
The authorities are always on lookout to make roadways safer either by improving engineering measurements or by traffic monitoring. However, at times it is not advice able or feasible to implement safety improvement ideas in the whole city. The reason accidents do not occur uniformly, characteristics of roadways vary significantly. The reason may also be the geography of area, demography of area, funds allocation or combination of these. Safety improvement programs are required to be applied first in those areas (or zones) where the accident occurrence is high and land area is small. In this connection it is necessary to define zones.
What is Zoning?
The zoning process provides a systematic method for identifying accidents prone locations for safety improvement programs in cost-effective manner. Zoning identifies a subset of area having high number of accidents with respect to as little land area as possible. The motive is to gain maximum possible efficiency. The efficiency can be expressed as a ratio -
When the ratio is in form –> “ % of accident problem addressed > = % of land area covered” than zoning will yield a meaningful results.
The establishing of zones encourage safety programs where improvement measure can be incorporate where otherwise it is not feasible to apply safety improvement measures citywide. Zoning brings the following profits:
- Efficient delivery of safety improvement programs where a majority of accident crashes or accident victims or economic loss exits.
- Efficient use of funds in gray zones than it was applied to Whole City.
Zone Preparation
Zoning is quite simple and it includes the following steps:
First of all pick up the accident problem e.g. more number of crashes involving heavy vehicles, two wheelers or pedestrian, high dose of drugs or alcohol that effect driving or stretch forcing monotones driving etc. This further need detailed accident data from FIR, Road Inventory and other sources. The data should be complete and sufficient enough to produce stable maps. At least three to four years data should made be available for the purpose because more data shows more better clusters of accident locations helpful in establishing zones.
Second the available data of accidents can be mapped manually or by a computerised mapping system often called as Geographic Information System (GIS). Computerised mapping is obviously more efficient in making the correct location of each event.
The GIS permits the analysis of full range of variables appearing in FIR Data, Road Inventory Data and other streams of data. It establishes a link among different streams of data pertaining to accident. These data records are to be entered in computer with the location information. There after the maps can be created to show the crashes not only of target groups but also of various subgroups e.g. early morning accidents or accidents at intersections. Separate maps are needed to display different subsets of data or different colour /symbol scheme could be adopted to show type of accidents.
Defining Zones
A visual examination of map will show whether accident crashes of interest clusters in some way in an area of city. If the clustering is not apparent i.e. map shows that target-groups events are randomly spreaded than problem may not be zoneable i.e. percentage of addressable problem is less than the percentage of land area covered. On the other hand if clustering is apparent with some dispersion it will show a some kind of pattern.
To identify zones it is necessary to provide some qualification to the concern zone. Some initial shape or pattern should be selected for zones and also fix some number of accidents that must fall in that area i.e. defined as zone. In establishing the pattern search should be made first for circular zones than for linear zones there after other patterns.
Search for circular zones
Experts says that accidents occur more frequently in a radius around some place e.g. around some work place, residential place, hospitals, schools or intersection. For study purpose accidents occurring within a radius of one or two kilometer will be a manageable area where safety improvements programs can be initiated. The circular zone must be characterised by minimum number of accidents; this rating will make it enable a deserving order zone to process safety improvement programs. The rate depends upon the size of sample of number of reported accidents available, how many accidents cluster and overall land area of concern covered. The number of accidents in a zone is simply an indicator where as clustering of accidents is more of high concern.
Search for linear zones
The safety improvements put their concentration along a road segment where accidents occur more frequently, which may be a part of circular zone. The GIS helps out in displaying those locations both on single strip of roadway as well as in circular zone. A manageable length for road segment and number of minimum accidents over a period of time must be allocated to make that linear zone ordered linear zone for safety improvement programs.
Final pattern of zones
With the aid of GIS map shows different pattern of interest where these pattern may be contiguous or scattered. When the contiguous zones overlap each other they are of more importance and demand high concentration. It may be possible when two circular zones having high number of accidents at periphery they can be clubbed with other zones and a new pattern can be created. It may be better to add or delete few locations to keep neighborhood zone intact. Boundaries may be revised to a square or rectangular area to generate better impact of safety improvement programs.
Ordering of zones
After establishing of circular, linear zones restructure the same if required to fall in some order. Finally for all the zones percentage of accident problem addressed and land area is required to be calculated in order to program coverage efficiency. If the ratio of percent of problem addressed to the percent of land area covered in the zone is much less than the defined zone may need to be re-examined. If efficiency ratio is high e.g. 60% of accidents of interest in 20% of concerned, land area will definitely demand for safety improvement measures. If the ratio is not going to be high that area may be studied as a non-zoneable area.
Zones Utilisation
- Once the zones are finalised in some order they are required to evaluated to access accident problem in depth through FIR and Inventory details etc. The evaluation should bring out limitation pertaining to driver, pedestrian, trees, medians, intersections, road furniture and inadequate lighting etc.
- Situation permitting collision need to be highlighted e.g. vehicles are too close to pedestrians when making right or left turn.
- Negative behaviour of driver or pedestrians or cyclist or other road users need to be examined with more importance.
- The high risk factors which effect the safety of pedestrians or other road users such as high speed, inadequate timing or operation of signal are need to be examine thoroughly.
Conclusion
The zoning application is not limited to one particular problem. In reality any highway safety problem, which can be described by the geographic location of occurrence will be a good exercise for zoning. The above strategy could be applied to all type of vehicle crashes, roadway maintenance activities and pedestrian safety etc. In fact zoning can potentially be applied to any highway problem that has a mappable target measure and could benefit from more efficient safety improvement program deployment.