  We propose a data structure that stores, in a compressed way, object
trajectories, which at the same time, allow to efficiently response queries
without the need to decompress the data. We use a data structure, called
$k^{2}$-tree, to store the full position of all objects at regular time
intervals. For storing the positions of objects between two time instants
represented with $k^{2}$-trees, we only encode the relative movements. In order
to save space, those relative moments are encoded with only one integer,
instead of two (x,y)-coordinates. Moreover, the resulting integers are further
compressed with a technique that allows us to manipulate those movements
directly in compressed form. In this paper, we show an experimental evaluation
of this structure, which shows important savings in space and good response
times.
