Delays on the Underground

Delays on the Underground

This Daisy Chart was produced using the drawing template, delays.dyt, using the data file, delays.txt, supplied with all versions of Daisy. It is a graphical representation of all the delays on the various lines of the London Underground in March 1996.

The data has been analysed into three sets of nodes, each of which is shown as an arc of the circular Daisy Chart. These are the Line, the Day of the Week and the Area of operation that caused the delay.

Two histograms are shown on each node; the number of delays, green, and the total delay in minutes, violet.

The lines of links between the nodes show the relative strengths of the connections between nodes. In this Daisy Chart, they are shown in terms of the total delay.

At a first glance, it would appear that there were serious delays on the Jubilee Line on Mondays, involving stations and safety. By using the mouse to select the actual delays involved, it was found that the delays were due to the closure of two stations because of unsafe floors for several hours. Something, that although a serious inconvenience to passengers at those locations, did not cause any danger to passengers or actually affect the overall running of the network.

Other strong links show power and track problems on the Northern Line. These are currently being addressed in a multi-million pound total re-equipment of the line.

Note that most of the other links are weak, which indicates that delays are of a random nature and not due to systematic management, staff and equipment failures.