An accident black spot is a term used in road safety management to denote a place where road traffic accidents have largely been concentrated. At certain sites, the level of risk might be higher than the general level of risk in surrounding areas. Crashes will tend to be concentrated at these relatively high-risk locations. Such locations are described as black spot. Another term known as blacklength, implies a stretch of road other than intersections with a certain number of crashes per kilometer, within a specified number of years. However, there is no universally accepted definition of a 'blackspot' or 'blacklength'.
In general, the number of crashes takes place by three factors: (i) the road environment; (ii) the condition of vehicles; and (iii) the skills, concentration and physical state of road users, usually termed as human factor. In majority of cases, a crash occurs when the driver's performance level is insufficient to meet the performance demands of the road environment. Most of the time, driver capabilities exceed performance demands. Engineering improvements in the road network lower performance demands on the driver. This increases the safety margin between the driver's performance level and the performance demands of the road environment, and reduces the probability of a crash.
The 'fatal', 'serious' and 'minor' accidents represent type of injury in an accident; while non-injury accident is termed as 'property damage only'. The definition of these injury types differ among the countries. A research study in New Zealand says, different crash evidences showed that injuries per accident and severity of injury have increased linearly with speed; that is why speed reduction is so important.
It is a significant issue by which an intersection or link (midblock section) can be designated by its severity in terms of crash propensity to alert drivers in advance and subsequent remedial measures. In Bangladesh, it has been observed that some accident prone sites are termed as blackspots; actually, it is a fallacy. Because, no definition of a blackspot has yet been formulated for Bangladesh context; that is why, such locations are referred to as an 'accidents prone areas' instead of 'blackspots'. Actually, there is no universally accepted definition for a blackspot. Moreover, the definition of blackspot varies from country to country depending upon number of crashes over a specified period within a specified area; for example, a blackspot in New Zealand is defined, in two different manners based on urban and rural environment, as a concentration of crashes within a 30m radius in urban areas, or a concentration crashes within a 250m radius in rural areas, while for both the cases, three or more fatal or serious injury crashes need to be occurred in consecutive five year period. Bangladesh has a very poor road safety standard; and hence accident countermeasures are very important. Most importantly authorities are unable to take countermeasures unless blackspots are identified. So it is urgently necessary to formulate the definition of blackspot for Bangladesh context; instead of passing off as 'accident prone area'. Once the blackspot is defined only then the total number of blackspots could be indentified; and undertake appropriate measures to prevent accidents.
At the first step, blackspots are targeted at improving safety on the road network through remedial treatment of the sites. One of the most cost-effective road safety interventions is to eliminate blackspots. The course of eradicating or improving accident blackspots in a road network consists of several phases; these are: (i) identification of blackspots, (ii) finding countermeasures, (iii) estimating effects, (iv) prioritising, (v) implementation, and (vi) follow-up and evaluation.
While analysing accident blackspots, the accident types which are defined by the road users' movement is very important for deriving countermeasures and understanding different crash patterns. The accident type represents diagrammatic presentation of vehicle-to-vehicle and vehicle-to-other-road-users movements. This way of diagrammatic presentation has been proved to be a powerful tool in the analysis of road accident problems, developing countermeasures and examining the changes and effects of countermeasures. It is important to determine the particular nature of accident problems by identifying what type of accident is predominant, whether they are at intersection or link and what proportion of casualties they result in. In the accident study, it is important to define the three fundamental variables: (i) accident types, classified by the movements of the road users; (ii) accident locations, classified into intersections and links; (iii) and road type, classified by functional classes of road.
Without identifying blackspots no intervention and priority selection seem to be feasible. It is particularly true for the urban areas; especially in the big cities like Dhaka, where pedestrian casualties is a matter of concern; proper countermeasures are not possible for not having identified blackspots. Road users' movement diagrams are not also possible without definition of blackspot. Consequently, comprehensive countermeasures could neither have been possible to address pedestrians' problems in the urban areas, nor appropriate countermeasure could have recommended on the highways except for a few 'accident prone areas'. Thus, the identification or shortcomings in design or what so ever could not have been properly addressed for not having defined blackspots and 'collision diagrams'. Consequently, reactive countermeasures are not being addressed properly, not to speak of proactive measures which require highly expert professionals and use of road safety audit software. The urgency for the formulation of blackspot definition is thus critical and soonest the best.
The writer is Traffic cum Road Safety Engineer.
E-mail: [email protected]
© 2024 - All Rights with The Financial Express
