Global road traffic injury statistics:Challenges,mechanisms and solutions

High-quality data are the foundation to monitor the progress and evaluate the effects of road traffic injury prevention measures.Unfortunately,official road traffic injury statistics delivered by governments worldwide,are often believed somewhat unreliable and invalid.We summarized the reported problems concerning the road traffic injury statistics through systematically searching and reviewing the literature.The problems include absence of regular data,under-reporting,low specificity,distorted cause spectrum of road traffic injury,inconsistency,inaccessibility,and delay of data release.We also explored the mechanisms behind the problematic data and proposed the solutions to the addressed challenges for road traffic statistics.

Road-safety recognition and network equilibrium with perceived route-choice sets

Safety is regarded as the second basic need in Maslow’s hierarchy of needs(1943),and safety recognition and circumvention behaviour in the route-choice decision-making process should therefore be accommodated in network-traffic equilibrium analysis frameworks.This paper proposes a framework by which crash frequency,forecasted using the safety-analysis method or compiled from historical data for intersections,is used to measure the safety consciousness of drivers.Drivers are then classified into different groups according to their acceptable-risk thresholds,and each group has its own route-choice set.Decision behaviour whereby drivers are willing to bear additional costs in order to circumvent travel risk is incorporated into the variational inequality model based on the user equilibrium in the perceived route-choice set(UE-PRCS),which is an extension of Wardrop’s first principle.The Frank–Wolfe algorithm,based on the convex combination method,is employed to obtain the solution.A small road network is used as a case study to illustrate the proposed framework,incorporating risk recognition and circumvention behaviour under different combinations of traffic demand and risk-sensitivity group ratio.The results show that the standard user equilibrium is a special case of the UE-PRCS,but that the UE traffic state is more common than the UE-PRCS under different parameters.

Estimating hotspots using a Gaussian mixture model from large-scale taxi GPS trace data

The data collected from taxi vehicles using the global positioning system(GPS)traces provides abundant temporal-spatial information,as well as information on the activity of drivers.Using taxi vehicles as mobile sensors in road networks to collect traffic information is an important emerging approach in efforts to relieve congestion.In this paper,we present a hybrid model for estimating driving paths using a density-based spatial clustering of applications with noise(DBSCAN)algorithm and a Gaussian mixture model(GMM).The first step in our approach is to extract the locations from pick-up and drop-off records(PDR)in taxi GPS equipment.Second,the locations are classified into different clusters using DBSCAN.Two parameters(density threshold and radius)are optimized using real trace data recorded from 1100 drivers.A GMM is also utilized to estimate a significant number of locations;the parameters of the GMM are optimized using an expectation-maximum(EM)likelihood algorithm.Finally,applications are used to test the effectiveness of the proposed model.In these applications,locations distributed in two regions(a residential district and a railway station)are clustered and estimated automatically.

Left-turning vehicle-pedestrian conflicts at signalized intersections with traffic lights: Benefit or harm? A two-stage study

Purpose: Vehicle-pedestrian conflicts are com mon at road intersections when traffic lights change. However, the impact of traffic light on transportation safety and efficiency remains poorly understood. Methods: A two-stage study was used to survey the proportion of intersections with conflicting traffic lights and the related transpoilation efficiency and safety were evaluated as well. First, a cross-sectional study estimated the proportion of signalized intersections with conflicting left-turning vehicle-pedestrian traffic lights in Changsha city, China. Second, a natural experiment compared transportation efficiency and safety between intersections w让h and without conflicting left-turning vehicle-pedestrian traffic lights. Risky conflicts, where motor vehicles violated laws and failed to yield to pedestrians in crosswalk were used as a surrogate for transpoilation safety. The number of motor vehicles and pedestrians passing through the intersections per second and per meter were used to estimate transportation efficiency. Data were collected and analyzed in 2015 (from March to December). A search of on line news from domestic media sources was also conducted to collect pedestrian injury data occurri ng at the intersections. Results: About one-fourth (57/216) intersections had conflicting left-turning traffic lights (95% Cl: 20.5%, 32.3%). Risky vehicle-pedestria n con flicts were more frequently observed at in tersections with conflicti ng lights compared to those without (incidenee rate ratio (IRR) 3.13;pedestrians: IRR = 4.02), after adjusting for type of day (weekday vs. weekend), the time period of observation, and motor vehicles traffic flow. Intersections without conflicting vehicle-pedestrian traffic lights had similar transportation efficiency to those with conflicting lights after controlling for covariates (p > 0.05). The systematic review of news media reports yielded 10 left-turning vehicle-pedestrian crash events between 2011 and 2017, involving 11 moderate or severe pedestrian injuries and 3 fatal pedestrian injuries. Conclusion: Over one-fourth of road intersections in Changsha city, China have conflicting left-turning traffic lights. Conflicting traffic lights cannot improve transportation efficiency, but increase risky conflicts between vehicles and pedestrians.