Vehicle Specific Power (VSP) has been increasingly used as a good indicator for the 9 instantaneous power demand on engines for real world driving in the field of vehicle emission and fuel 10 consumption modeling. A fixed vehicle mass is normally used in VSP calculations. However, the influence 11 of passenger load was always been neglected. The major objective of this paper is to quantify the influence 12 of passenger load on diesel bus emissions and fuel consumptions based on the real-world on-road emission 13 data measured by the Portable Emission Measurement System (PEMS) on urban diesel buses in Nanjing, 14China. Meanwhile, analyses are conducted to investigate whether passenger load affected the accuracy of 15 emission and fuel consumption estimations based on VSP. The results show that the influence of passenger 16 load on emission and fuel consumption rates were related to vehicle's speed and acceleration. As for the 17 distance-based factors, the influence of passenger load was not obvious when the buses were driving at a 18 relative high speed. However the effects of passenger load were significant when the per-passenger factor 19 was used. Per-passenger emission and fuel consumption factors decreased as the passenger load increased. 20It was also found that the influence of passenger load can be omitted in the emission and fuel consumption 21 rate models at low and medium speed bins but has to be considered in the models for high speed and VSP 22 bins. Otherwise it could lead to an error of up to 49%. The results from this research will improve the 23 accuracy of urban bus emission and fuel consumption modeling and can be used to improve planning and 24 management of city buses and thus achieve energy saving and emission reduction. 25

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Due to stop-and-go events, bus stops are often treated as “hot spots” for air pollution. The design of bus stops should be optimized to reduce emissions and exposure for transit commuters. The objective of this study was to analyze the impact of bus stop platform types on vehicle emissions and individual pollution exposure. Second-by-second emissions data were first collected from one bus using a portable emission measurement system (PEMS). Microscopic traffic simulation was then used to estimate overall traffic emissions under six scenarios with different bus stop settings. Numerical simulation of pollutant dispersion was also conducted to calculate individual pollution exposure at bus stops. The results of PEMS tests showed no significant differences between bus emissions generated near two different types of stops. However, the effect of platform types on overall traffic emissions was revealed using traffic simulation. The results demonstrated that bus bays reduced the emissions of other heavy-duty vehicles. However, bus bays were not always effective during rush hours. The study also highlighted the importance of the location of bus stops, the number of bus lines, and the length of the platform, in addition to dynamic characteristics of traffic flows in the design of bus stop platforms. Bus stop platforms also affected individuals’ exposure due to the changes in the pollutant flow field. The passenger’s exposure at one bus stop was influenced by both the platform type and standing location. Results suggested that in a condition with a wind direction perpendicular to the bus stop shelter, the total exposure level to CO was lower at the bus bay stop if a passenger stood at the upstream of the station platform. However, the exposure was less at the downstream of the curbside bus stop.