The Parisian metro seems to be a conspiracy to make Paris feel larger than it is: the distances between stations are smaller than in London. In central Paris, it feels as if the average distance between two metro stations is more or less the equivalent distance between Leicester Square and Covent Garden in London. Because it’s underground and dark, we overestimate the distance we travel. Perhaps there is a difference between the strategies of London Underground and Paris metro.
There are more stations and more lines, therefore more interchanges in Paris compared to London. Because there are more stations, density of stations in central Paris is much higher, which leads to the conclusion that the catchment area for each metro station is smaller. Each station does not have to cope with a huge number of people getting on and off. There are certain stations which act as nodal points of the public transport system, therefore they are built larger to cope with the extra traffic. This avoids overcrowding in stations and platforms which slow down the progress of the train, as is often the case in London. Services are frequent so that overcrowding on platforms does not accumulate. Perhaps it’s more attributable to Gallic impatience than French efficiency, but the length of time that the metro spends at each station is shorter than in London: the frequent Parisian metro stops more often, but the stops are shorter compared to the tube. Also, metro lines are shorter and they function as transport within central Paris: RER and trains link the suburbs to the centre.
The London tube system is in many aspects, the opposite of the Paris metro, and perhaps therein lie problems for London. There are fewer lines and stations in central London, making each station’s catchment area larger. There are more people per station than in Paris. The stations are further apart, and some lines share sections of the track (e.g. Circle, Hammersmith and City, Metropolitan). Traffic builds up at certain stations despite regular services, as anyone who is hardy enough to try to get on the tube in Victoria knows. The average time spent at stations is longer, and overcrowding both in the carriages and on the platforms make a smooth running of the tube difficult. This naturally leads to knock-on effects which cause delays in the services. The London Underground not only serves as a means of transport within central London but also as commuter lines in and out of suburbs, therefore serves several purposes at the same time. With new or improved Crossrail, Thameslink and East London Railway, the situation may become better in a decade or so but there are still more lines needed in West and South London. And it’s easy to forget that London has a much larger population and will therefore need more capacity than Paris.
This is probably an over-interpretation of two differing public transport systems in London and Paris, though I think London would not be worse off if it looks to Paris for ideas for a better public transport.