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Chandra S.,Indian Institute of Technology Roorkee | Mehar A.,National Institute of Technology Warangal | Velmurugan S.,Traffic Safety India
KSCE Journal of Civil Engineering | Year: 2015

Mixed traffic has always been a major concern in all studies related to estimation of capacity of a highway in developing nations like India. The problem of mixed traffic is generally circumvented by making use of passenger car equivalency factors for different categories of vehicles and converting them into equivalent number of Passenger Cars Units (PCU). However, capacity is also required in terms of vehicles per hour, particularly for quick estimation of volume-to-capacity ratio on a highway. The present study investigates the effect of traffic mix on capacity of four-lane, six-lane divided highways in India. All vehicles on a highway are divided into five categories namely standard car, big car, heavy vehicle, motorized three-wheelers and motorized two-wheelers, and effect of each vehicle type on capacity of the highway is evaluated. The VISSIM software is calibrated and used to generate the traffic operations based on field data using capacity as the measure of performance. Speed-flow curves are developed to find simulated capacity values for different combinations of standard car and one of the remaining four types of vehicles in the traffic stream. The results are finally combined to propose the generalized equations to determine capacity when all or few of the five categories of vehicles are simultaneously present on a highway. © 2015 Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg

Mehar A.,Indian Institute of Technology Roorkee | Chandra S.,Indian Institute of Technology Roorkee | Velmurugan S.,Traffic Safety India
Journal of Transportation Engineering | Year: 2014

Passenger car units (PCU) of different types of vehicles are required to convert a mixed traffic stream into a homogeneous equivalent, and thereby to express the mixed traffic flow in terms of equivalent number of passenger cars. Earlier studies have reported that PCU for a vehicle is dynamic in nature and changes with traffic volume and proportional share of a vehicle type in the traffic stream. The present study provides PCU values for different types of vehicles typically found on interurban multilane highways in India at different levels of service (LOS). Traffic simulation model VISSIMis used to generate the traffic flow and speed data for conditions that are difficult to obtain from field observations. Important VISSIM parameters are first calibrated to reflect mixed traffic flow behavior and then the software is used to draw the speed-volume relationships for cars and one of the remaining four categories of vehicles in the traffic stream. The proportion of second category of the vehicle was also varied to observe its effects on PCU values. Finally, PCU values are suggested for different type of vehicles at different LOS and for different traffic composition on four-lane and six-lane divided highways. © 2014 American Society of Civil Engineers.

Pulugurtha S.S.,University of North Carolina at Charlotte | Self D.R.,Traffic Safety India
International Journal of Injury Control and Safety Promotion | Year: 2015

This paper focuses on an analysis of pedestrian and motorists’ actions at sites with pedestrian hybrid beacons and assesses their effectiveness in improving the safety of pedestrians. Descriptive and statistical analyses (one-tail two-sample T-test and two-proportion Z-test) were conducted using field data collected during morning and evening peak hours at three study sites in the city of Charlotte, NC, before and after the installation of pedestrian hybrid beacons. Further, an analysis was conducted to assess the change in pedestrian and motorists’ actions over time (before the installation; 1 month, 3 months, 6 months, and 12 months after the installation). Results showed an increase in average traffic speed at one of the pedestrian hybrid beacon sites while no specific trends were observed at the other two pedestrian hybrid beacon sites. A decrease in the number of motorists not yielding to pedestrians, pedestrians trapped in the middle of the street, and pedestrian–vehicle conflicts were observed at all the three pedestrian hybrid beacon sites. The installation of pedestrian hybrid beacons did not have a negative effect on pedestrian actions at two out of the three sites. Improvements seem to be relatively more consistent 3 months after the installation of the pedestrian hybrid beacon. © 2013 Taylor & Francis.

Schueller H.,Traffic Safety India
ICTIS 2011: Multimodal Approach to Sustained Transportation System Development - Information, Technology, Implementation - Proceedings of the 1st Int. Conf. on Transportation Information and Safety | Year: 2011

This paper presents the main results from modeling relationships between road design, and speed behavior as well as the influence of speed in the occurrence of accidents. In order to describe speed choice of drivers by using parameters of the speed distribution different kinds of classification of free-flow-vehicles were analyzed as well as spatial and temporal aspects of spot speed measurements. Results of multiple regression models for mean speeds and 85-percentiles of the speed distribution are documented and discussed. Road classification, cross section characteristics, land-use and the road surface condition among others are found to be significant parameters that correlate with driving speed. Generalized Linear Models are used to describe the influence of mean speeds on the occurrence of road accidents. This is done for different accident groups under consideration of the annual daily traffic and a parameter that describes the length and type of land-use of the adjacent buildings next to the road section. The relationship between speed and accidents count is described using a power function. © 2011 ASCE.

Olofsson E.,Paediatric and Adolescent Medical Care | Olofsson E.,Gothenburg University | Olofsson E.,Sahlgrenska University Hospital | Bunketorp O.,Gothenburg University | And 4 more authors.
Safety Science | Year: 2015

Aim: To investigate the use and protective effect of helmets in children injured in bicycle crashes and changes in injury patterns during a period of increased helmet use. Method: Injuries in 4246 children below 16. years of age, who attended an A&E ward after a bicycle crash in the Gothenburg region during 1993-2006, were analyzed. The injury severity was classified according to the Abbreviated Injury Scale. The occurrence of skull/brain injuries and facial injuries was analyzed for 3711 children with respect to injury severity, helmet use and demographic and crash-related factors. Changes in injury patterns during the period were analyzed for 4246 children with no regard to helmet use. The ratio of the number of subjects with head injuries to the number of subjects with extremity injuries of any severity and of at least moderate severity was used to estimate the protective effect of helmet at a population level. Results: Helmets were used by 40% of the injured children at the beginning of the period and by 80% at the end; much less frequently by teenagers, especially girls. The adjusted odds of serious or more severe skull/brain injuries and moderate or more severe facial injuries with a helmet were about one fourth of those without a helmet. The proportion of children with skull/brain injuries did not change significantly during the period. Serious or more severe skull/brain injuries were noted more often during the latter half of the period, most often in children without a helmet. The proportion of children with facial injuries decreased, and the proportion with injuries to the upper extremities increased, also for moderate and severe injuries. The ratio between the number of children with head injuries and the number with extremity injuries decreased for injuries of any severity and for moderate or more severe injuries. Conclusions: Bicycle helmets have an obvious protective effect against head injuries in children, regardless of the crash circumstances. Teenagers must be informed about the high risk of skull/brain injuries in bicycle crashes without a helmet. The increasing occurrence of injuries to the upper extremities needs attention. © 2015.

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