【正文】 pandgo conditions [10]. The relationship between emissions and speed can be seen in Table 1. Table 1 Emissions level in different speed [11,12] Speed (km/h) CO (g/km) CO2 (g/km) Fuel consumption (g/km) 10 310 130 20 240 96 30 200 79 40 170 65 50 150 55 60 145 48 70 138 43 80 130 40 100 110 50 With respect to air quality impacts, congestion pricing can be expected to improve air quality in two ways. The first impact es from the reduced level of congestion on the facility, pared with the level of congestion on the unpriced road. The second impact on emissions is due to the reduced number of vehicles on the road facilities. To the extent that higher prices succeed in reducing vehicle miles traveled, there will be fewer vehicles on the road. It is clear that reduced travel demand in peak periods reflects fewer and shorter trips being made and results in higher travel speeds during peak periods, with consequent reductions in vehicles emissions during peak periods. However, the bulk of daily travel occurring in offpeak periods may be negatively affected, as some peak travelers shift their time of travel to offpeak periods to avoid tolls. Overall beneficial impacts on air quality may thus be smaller than that suggested simply by peak period travel demand reductions. This reduction cannot be measured directly, but will have to be calculated from the information on traffic diversion, congestion reduction, and ridesharing increase. In the long term, congestion pricing could lead to increases in use of alternative travel modes for all daily trips, thus reducing total daily emissions. 4. Social justice Sustainable development has three widely agreed metagoals: sustainable economic development, environmental protection and social justice. All three goals must be addressed together if development is to be sustainable. Much attention has been paid to economic development and environmental protection, but less attention has been paid to social justice. Social justice (equity) contains economic equity and environmental equity. Economic equity issues resulting from congestion pricing are difficult to address pletely. Some people have argued that road pricing is regressive, in that it will bear more heavily on poorer car users, short distance journeys, and on those living adjacent to the cordons。 up till now, it is the most wellknown example of a large metropolitan area that has implemented congestion pricing. However, congestion pricing has not seen widespread use in practice due to theoretical and political reasons. Some potential impacts of road pricing remain unknown, and the sustainability of congestion pricing for urban development requires further study. Sustainability is normally taken as basic objectives in the assessment of transportation policy. The idea of sustainable transportation emerges from the concept of sustainable development in the transport sector and can be defined as follows [1], “sustainable transportation infrastructure and travel policies that serve multiple goals of economic development, environment stewardship and social equity, have the objective to optimize the use of transportation systems to achieve economic and related social and environment goals, without sacrificing the ability of future generations to achieve the same goals”. Sustainable transportation systems require a dynamic balance between the main pillars of sustainable development, . economic development, environmental protection and social justice for current and future generations. In the context of sustainable transport systems, how congestion pricing can contribute to economic growth, environmental protection and social justice is examined in this paper. The rest of the paper is structured as follows. In section 2, the impacts of congestion pricing on economic development are described. Section 3 presents the contribution to environment protection, and the relationship between social justice and congestion pricing is analyzed. Some conclusions are given in section 5. 2. Economic development 2020 Workshop on Power Electronics and Intelligent Transportation System9780769533421/08 $