I also recommend a visit to the Shanghai Museum of Urban Planning to anyone curious about population density, retail clusters or transportation infrastructure.

我还建议，对人口密度、零售集群或者交通基础设施感兴趣的人可以去上海城市规划馆参观。

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From the downtown to the urban fringe, the greening coverage is increased along with the decrease of the population density and building density.

从市中心到城市边缘，随着人口密度和建筑密度的下降，绿化的数量逐渐增加。

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Floodway; high-flow diversion Natural or man-made bypass channels or conduits that redirect flood waters around or away from urban centers or area of high population density.

泄洪道，分洪道，溢流槽天然或人造的泄洪渠或泄洪管道，以引导洪水绕过或远离城市中心或人口稠密地区。

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One study has suggested that the tax system alone reduces the population density in urban areas by 15%.

ECONOMIST: Urban sprawl

Probably this worry derives from the difference in population density between urban and rural or small town areas, but there is a tacit implication that non-urban dwellers are more expendable than urban dwellers.

FORBES: 1st Person | Facing an Unsettled Future After Radiation Exposure

Population density not only increased the vulnerability of urban centres but magnified the impact of natural disasters, delegates heard.

BBC: NEWS | Science/Nature | Losing sight of the countryside