Research On The Risk Assessment Method Of Crowd Gathering In Urban Open Public Space Supported By Spatiotemporal Big Data

With the rapid development of urbanization in China,a large number of open public spaces have been built in urbans to meet the living needs of urban residents.However,the construction of emergency management system of urban open public space lags far behind the growth of its quantity.Once an emergency breaks out,it is easy to cause serious casualties and property losses.Therefore,it is urgent to establish an assessment method for crowd gathering risk in urban open public space,prevent possible emergencies through pre-risk assessment,and provide decision support for risk prevention and emergency management in urban open public space.This study proposes a risk assessment method for crowd gathering in open public space supported by spatio-temporal big data,which is mainly divided into two parts:(1)With the support of Tencent User density data(TUD),a large-scale fine-scale crowd density estimation method for urban open public space is established.TUD-population correction function is used to correct the TUD grid to estimate the crowd density of open public space;(2)With the support of multi-source spatio-temporal big data,a risk assessment method for crowd gathering in urban open public spaces is established.This method is used to identify key open public spaces,and comprehensively and effectively assess the crowd-gathering risk in urban open public spaces by spatial quantitative expression.Taking the inner region of the outer ring road of Shanghai as the study area,the study conducted a quantitative assessment of the crowd-gathering risk in open public space,drew a risk map to show the risk level,and revealed the spatial and temporal distribution pattern of open public space with high crowd-gathering risk.The results show that the estimation results of population density in open public space have high accuracy and can be used to support the risk assessment of crowd-gathering.The spatial and temporal distribution of crowd gathering risk in open public space is heterogeneous.The highest risk of gathering occurred at 13:00 on weekdays and 17:00 on weekends in the study area.The open public spaces with high risk grade were mainly distributed in the concentrated commercial office buildings in Huangpu district,Xuhui District,Changning District,Jing 'an District and Hongkou District.According to the changing characteristics of crowd gathering risk of open public space in the study area,the study area was divided into three different risk prevention areas,and the risk prevention deployment could be carried out pertinently.The proposed approach can integrate the internal and external factors of open public spaces,and adjust the parameters according to the characteristics of urban open public space in different regions,so as to calculate the dynamic risk value of crowd-gathering.The evaluation results can provide help for urban planning from the risk level,and provide decision-making basis for improving risk management levels in urban open public space crowd-gathering and reducing casualties and losses of accidents.