What I wondered about that data set is, if two people living/working at two locations, consistently take taxis to meet at various other locations at the same times, could that pattern be identified in the data?

That is, are there locations A and B such that there are matching trips to locations M1,M2,... at times T1,T2,... i.e. (A,M1,T1),(B,M1,T1),(A,M2,T2),(B,M2,T2) and perhaps reverse trips (M1,A,T1+x) etc?

Further classification of M* -- hotels, for example -- could classify the nature of the meetings. You might be able to identify the addresses of people having affairs, or other deliberately secret rendezvous.