Research On The Method Of Reducing Emissions On The Urban Intersection Based On Microcosmic Simulation

Nowadays, accompanied with the people's life growing better, and the quantities of the vehicles climbing, the pollution of air by the vehicles is growing severe unavoidably. Research shows that the increase of retain measure for motor vehicles is the direct cause of increased motor vehicle pollution. The urban intersection which is playing as the hinge of the traffic, its contribution to the emission is very large. The idle speed in the intersection introduces a high pollution of the vehicle, especially the CO. And the frequent performance of acceleration and deceleration in the intersection all lead to the heavy emission of the vehicle.Referring to the environmental problems and the treatment methods of the vehicle emissions, there are many research results at home and abroad.It's mainly on the fuel modification, the purification inside the engine and outside the engine,the control of the traffic demand; And there are researches starting from the simulation to analysis the vehicle emission.By using the TSIS software, taking the GongNong square for example, this thesis performs a simulation by using the module CORSIM. This simulation mainly emphasizes on the three main vehicle emissions (CO, HC and NOx).The software specifies the vehicles into four types according to the fleet (length), performance index. They're carpool, passenger car, bus and truck. And here the'carpool'means that a car consists of two or more people who almost share the same route, and so there will be fewer vehicles on the freeways. That's an effective way to reduce the private cars on the road, and consequently the emissions and the fuel consumptions that the vehicles introduced would be weaken largely. But here in China, the use of carpool is so thin that we almost can neglect it in the traffic planning. In this thesis, the carpool is ignored, and the passenger car is divided into the high-performance car and the low-performance car, and ultimately the vehicle type is defined as high-performance car, low-performance car, truck and bus.After the microcosmic traffic simulation, the results of this thesis are displayed as follows:(1) In this thesis, researches on the road structure, the lane compositon, the traffic turning and the peak hour traffic volumes, etc. And later the primary treatment of those information is carried in order to set up the topology of this intersection.(2) After analysis on the composition, the characteristics, the parameters and the performance indexes of the TSIS software, and also the models of car-following and lane-changing, the formation and dissipation of the queue and the control delay, etc. Necessary adjustment is carried on the division of the vehicle types. (3) Under the original traffic control, according to the simulation of the square, it turns out that the vehicle emissions on the nanhu road and the renmin street are heavy, averagely on the medi-level or above, and in this square, the emission of CO is the heaviest, and then followed by NOx, the emission of HC is the lightest;(3) We can see exactly the pollution degree of the different road section inside the intersection. Generally the pollution of this intersection is heavy, and especially the renmin road, which is performing as the main road in this city.(4) According to the vehicle emission of the square under the current traffic control, relevant measures are put forward, respectively the incomplete-interchange (project A) and the modified-clover-interchange (project B).(5) And then a new modified project is put forward according to the existing states of this square: an incomplete-interchange, which makes the renmin road be a interchange, this interchange can offer a better channelization by leaving a special lane for the through flow of the renmin street, separating the main flow of the renmin road and coming to a aim to eliminate the influence of the traffic control, and also weaken the collisions with other flows. In this way the delay is reduced, and from another aspect, the frequent of the variation of the speed is reduced too, and consequently the vehicle emission of the intersection is improved;(6) By using the modified-clover-interchange, the flows turn left by running through the interchange ramps, and so the collisions among the different flows are alleviated. This interchange reduces the queue delay that introduced by the traffic control and the frequency of the variation of speed effectively, and finally the vehicle emission in this intersection is reduced largely;(7) The two new modified projects all improve the vehicle emission with different degree. About the reduction of the emission, project B is better than A by 6%. About the reduction of NOx, project A is better than project B by 3%. And in CO, project B is better than project A by 7%. In HC, project B is better than project A by 13%. In traffic delay, project B has the smallest queue delay, a reduction of 99.39% to the original project. Project A also has a better of the queue delay, its reduction is 34.30%; Based on the above analysis of the three projects, that we can see the project B is the best one.This thesis is aiming to reduce the vehicle emissions in the road intersection. After the analysis of the degree of the emission, it mainly analyses the total amount of the main vehicle emission. And at the same time, traffic delay is chosen as another transportation performance criterion. Giving consideration to the vehicle emission and the traffic flow, two new modified projects are presented to reduce the vehicle emission and improve the traffic flow simultaneously.