Study On Emission Law Based On The Prediction Of The Operating Speed Of Typical Highway Alignment Combination

With the development and progress of urban society and the improvement of people's living standards,the number of motor vehicles is increasing,and their use is becoming more and more frequent.Vehicle exhaust pollution is becoming more and more serious,affecting people's daily production and life.The source of exhaust gas is not only related to vehicle performance,but also closely related to road alignment.This paper combines vehicle running speed prediction with road alignment by running speed model,and combines MOVES comprehensive mobile source emission model to clarify vehicle exhaust emission law under different running speed under the influence of alignment index,which provides a reference for low-carbon road selection.The main research contents include the following aspects:Firstly,the paper introduces the typical alignment combination of roads and uses the concept of running speed.When predicting the running speed of typical road alignment combination,it is necessary to divide the road alignment combination into different analysis sections.According to the principle of road partition in operation speed prediction model,the road under different alignment combination can be divided into straight section,longitudinal section,horizontal curve section and curved slope combination section.By dividing the road sections and using the prediction model of running speed,the variation law of the running speed of vehicles on the road can be obtained.Secondly,this paper takes MOVES as the exhaust emission measurement platform.By using MOVES,the corresponding emission rates of vehicles on different road alignments are studied,and the emission laws of vehicles under different alignment indexes are obtained.It has been proved that the exhaust emissions of passenger cars are low when they travel at the speed of about 95 km/h on a straight road section.For large vehicles,we should try our best to drive at high speed within the allowable range of design speed.When driving on the longitudinal slope section,the longitudinal slope has a greater impact on the exhaust emission rate of passenger cars and large vehicles.With the increase of the slope,the exhaust emission rate is also increasing,and the passenger cars are more sensitive to the slope.When designing the horizontal curve,we should avoid choosing the small radius curve as far as possible.In order to reduce the exhaust emissions of small and large vehicles,smaller slope combination should be adopted as far as possible in the design of curved slope combination section.Finally,through a case study of a real road,by predicting and calculating the running speed of vehicles on the road,the variation law of vehicle speed during road operation is obtained.According to the running speed obtained,the road is simulated by MOVES,and the emission law of vehicles on the actual road is obtained.Then according to the result,the emission law is analyzed,and the improvement measures of road alignment index based on emission are put forward,and compared with the improvement measures based on road continuity index.It has certain reference significance for low carbon road type selection design.