Last couple of weeks I have been playing around with a dataset of taxi GPS traces from Beijing. This includes positions and timestamps from 10.000 individual taxis for a week.
Here is a map of speeds (red low, green high). It has been created by calculating the distance between consecutive pairs of traces from the same vehicle. When the time difference between a pair of such timestamps is less than 60 seconds, they are used to estimate a value instance based on their euclidean distance and time difference.
Datasets like this one are becoming increasingly available and they provide new information-rich ways to explore the spatial and temporal dynamics of urban systems. We are planning to evaluate this specific dataset, using spatiotemporal autocorrelation and if the results are encouraging we will be using it to estimate the speeds of the links of a transport model of Beijing.
I will come back to this to discuss the autocorrelation method we devised and share some results when we have made some more progress.