Study On Microscopic Vehicle Emissions Based On Shockwave

Shockwave is a kind of unstable traffic flow, which not only induces traffic accidents, but also results in traffic congestion. Vehicles affected by Shockwave will stop-and-go more than one time as the shockwave propagates, which leads to frequent emission "peaks". This paper has analyzed the changes of vehicle emission with shockwave qualitatively, and discussed the relationship between emission of Shockwave and emission of smooth traffic flow quantitatively, by combination of a micro-simulation model FLOWSIM and a micro-emission model MEM-RThe conclusions were as follows: The emission curve of a single vehicle affected by Shockwave appeared distinguished wave crests and wave troughs, which diversely from that of smooth flow. Vehicle emission of deceleration and idle was much lower than that of smooth flow, While vehicle emission of acceleration grow much faster and reach an emission "peak" around speed "peak". Through Lilliefors test, it had shown that both Shockwave data distribution function and non-shockwave data distribution function were abnormal. By Mann-Whitney test, the results indicated that the difference of emission data variance from different lanes was indistinctive. By comparing the shockwave emission matrix and non-shockwave emission matrix, results showed that the confidence interal of the ratio between shockwave emission and non-shockwave emission was (1.3147±0.0229), at a confidence level of 95%.The emission ratio was used to estimate shockwave emission induced by link entrance. The result was identical with that of other relative research. It was also certified applicable.