Four urbanization models 209respectively), outward urbanization progressively smoothes the metro-area bor-
der creating a compact rounded or oval form.
Satellite-cities model mosaic sequence
All urbanization occurs around a few (four in this case) satellite cities at
equal rates and in concentric-zones form. Consequently, each satellite receives a
quarter of the total urbanization at each stage, and the metropolitan area and
its border remains unchanged.
The selection of satellite cities for urbanization is governed by the following
priorities in order. Satellites are: (1) in the four compass quadrants and relatively
equidistant from one another; (2) in the outer half of an urban-region ring, i.e.,
nearer the urban-region boundary than the metro-area border; (3) connected to
themetropolitan area by a main road; (4) chosen from existing small cities, or
in their absence, towns.
Some explanations for the priorities are helpful. The distribution of all other
features, sites, and characteristics in the region was ignored in selecting satel-
lite cities and main roads. For coastal cities, satellites are relatively equidistant
though often not in four compass quadrants. Selecting satellites far from the
metropolitan area means that the satellite and metro area remain separate as
urbanization proceeds, and that the satellite-city model is clearly differentiated
from the concentric-zones and dispersed-sites models. The presence of a main
road between satellite city and metropolitan area helps make the satellite a log-
ical place for regional urban growth, and enhances direct comparison of the
satellite-cities model with the transportation-corridors model which uses the
same main roads. Finally, small cities may be better prepared for urban expan-
sion than are towns, due to the presence of urban infrastructure, park system,
and administrative structures.
Transportation-corridors model mosaic sequence
All urbanization occurs adjacent to a few (four in this case) main radial
highways connecting the metropolitan area with satellite cities, and progres-
sively extends at equal rates outward from the metro area. From a highway,
development extends outward in parallel bands, half on each side.
Transportation routes connect the metro area with the relatively equidistant
satellite cities selected in the satellite model. If no main road exists, a straight-
line route is established connecting a satellite city either to an existing main
road at a logical point or directly to the metro area. This is consistent with
theexpectation that if a satellite city grows, either existing secondary roads are
likely to be upgraded or a new road will be built to the metropolitan area.