The complexity of the directional construction in Chinese involves the following factors: (a) it can take a single directional item as the predicate; (b) two directional items can cooccur to serve as the predicate; (c) one or two directional items can be attached to a matrix verb in a single clause; (d) if more than one directional item is involved, their linear order can differ. I propose that the leading factor behind this complexity is that in Chinese a single Root can take different categories when merged in different syntactic positions. Therefore, the same directional item may in fact have the phonological form of a verb, a preposition, a part of a single preposition, or even a spatial aspectual marker in different directional constructions. I then place this account within the context of parametric studies of motion event constructions, showing that two new dimensions can be added: the special property of Roots in a language and the existence of Spatial Aspect in at least some languages.