Ride quality on London Underground

The ride quality experienced by a passenger depends on three things, the track geometric quality, the vehicle suspension and state of maintenance and the passenger's perception of the importance of the accelerations experienced. This paper will describe London Underground's understanding of the relationship between the track geometric quality and the vehicle characteristics and how important various aspects of these are to the customer. There is a balance to be struck between the cost of providing geometrically accurate track and the cost of sophisticated vehicle suspension systems which would smooth out track inaccuracies and the paper will address this issue. To be able to make a reasoned judgement on this balance it is necessary to know what the state of the track geometry and vehicle characteristics is at present, to know what the optimum is for given business aspirations and what needs to be done to achieve this optimum. The paper will present the current position and describe the historical influences that have caused it to be as it is, identify the changes to track and vehicles needed to reach the desired optimum and suggest how future developments win achieve this and improve the ride quality experienced by the passengers.