The variables of physical, socioeconomic, and neighborhood
factors together significantly affected the urban expansion in Beijing
(Table 5). Elevation and slope showed consistently negative
effects on urban expansion in the past forty years, except for
elevation during the period of 1984e1992. The percentage of urban
areas within a 210 m window had consistently positive effects on
urban expansion for all of the four periods. The socioeconomic
factors also showed significant influences on urban expansion, but
their effects varied over time. The distances to the city center and
the county center showed consistently negative relationships with
urban expansion, while the effects of the distance to roads on urban
expansion varied over time. The distance to the highways negatively
affected urban expansion after 1992, and the distance to
major roads only had effects on urban expansion in the period of
1992e2000 (Table 5).