The impact of urban transportation on air pollution and the role of subway inits control (Tehran, Beijing, Barcelona)

Many scholars believe that air pollution can be defined when it is mixed with  technical indicators. Therefore,in his legal dictionary, Garner has defined air  pollution as any material and harmful energy that directly or indirectly emit in the air in such as a way that harm the environment, welfare, or public health. Air pollution has both natural and synthetic origin. In the meantime, transport is one of the  causes of pollution that is in artificial emissions group and has a major contribution to air pollution.Urban rail transportation is considered as an efficient factor in reducing transport-related pollution, and thusin addition to its ability in rapid and massive transportation, subway can play an important role in sustainable urban development. In this article, we have tried to examine the role of transportation in urban air pollution as well as the subway role in reducing these emissions, and subways in Tehran, Beijing, and Barcelona havebeen investigated and the outstanding role of subway is identified because of the high volume of human transportation and reducing traffic in the city.Key words: transportation, air pollution, subways, traffi

Metro Passenger Flow Forecast with a Novel Markov-Grey Model

Accurate forecasts of passenger flow entering and leaving metro stations is an important work for Metro operation management, such as for the automatic adjustment of train operation diagrams or station passenger crowd regulation planning measures. In this study, Grey theory is introduced to develop a time series GM (1, 1) model for total passenger forecasting. Two modification factors determined by two minimum mean square error principles are proposed to decrease the discreteness of input data and thus improve the forecast accuracy. Moreover, the Markov chain approach is further used to optimize the residual error series. Passenger flow data entering and leaving the Xiaozhai station of Xi'an Metro Line 2 from September 1-30, 2015, were utilized to verify the effectiveness of the proposed method; the forecast results show that this novel Markov-Grey model performs well in terms of forecast accuracy with smaller SMSE and MAPE values. To this effect, the proposed method is especially well-suited to smooth passenger flow forecasting compared to other forecast techniques