  Nowadays, traffic monitoring systems have access to real time data, e.g.
through GPS devices. We propose a new traffic model able to take into account
these data and, hence, able to describe the effects of unpredictable accidents.
The well posedness of this model is proved and numerical integrations show
qualitative features of the resulting solutions. As a further motivation for
the use of real time data, we show that the inverse problem for the
Lighthill-Whitam and Richards (LWR) model is ill posed.
