The puls of the transport network does play a big role in the constitution of the cities puls. The pace of the departure of the public transport, the frequency of the stops, but also the location of the stations spatially drive this rhythm. Any live tracking transport site gives a good idea of the puls of the transport network.
The following visualisation of the commuter trains around Copenhagen give a really good impression of the frequency. It represents the realtime position of each train on an abstract network map.
Image by Jim Larsen / Click HERE to see the live map. Works best in Firefox or Safari
The time laps captured at a tube station visualizes the puls from a different angle and show how the arrival and departure of trains pump the commuters through the network.