With the exception of Monaco, which is an anomaly in every way, the Circuit de Catalunya has long been the circuit at which overtaking is more difficult than anywhere else in Formula One. 16 of the 20 races held at the circuit have been won from pole position, including every one in the past decade. In the past three years, normal overtaking manoeuvres have been measured in single figures; on average, there have been 2.3 'normal' passes for position per Spanish Grand Prix since 2008.

So if a circuit is going to provide a yardstick for the success of the 2011 regulations, which have so far seen an average of 24.5 'normal' overtaking moves per race, and many more with the use of DRS, then Barcelona is it...

The fundamental impediment to overtaking at the Circuit de Catalunya is that the 880m main straight is preceded by the fast Turn 16. It is a corner through which it is hard to follow another car closely and, when performance differentials between are small, this makes overtaking extremely difficult. Furthermore, teams have normally been testing at Barcelona and have optimised the car and tyre usage, which usually gives less variation in performance and strategy than normal.

Downforce levels are monitored by the car's on-board sensors and the closer you get to the car in front, the bigger the loss in downforce. This loss occurs across the whole car, but is more pronounced at the front, hence the tendency for the following car to understeer. The loss begins to occur when the gap between the cars is 3.5s. When one second behind, the chasing car loses approximately 7% of total downforce; when 0.5s behind, this rises to around 12%.

The traditional method of counting on-track overtaking relies on registering position changes from a lap chart; however, this method cannot take account of multiple passes on a single lap, or passes made on in and out-laps. The teams calculate the number of overtaking manoeuvres using a combination of video, timing data and GPS technology.

This method enables the 'value' of overtaking moves to be categorised for use in strategic calculations: for example, passes between team-mates are categorised separately because one driver can choose to let the other pass, although this is not automatically the case; similarly, passes by faster cars on those from the bottom three teams are categorised separately as their strategic importance is different.

However, there is no standard definition of a 'real' overtaking move, so differing conclusions can be reached according to the method used. Consistency of method is as important as overall accuracy.

As far as overtaking at Barcelona is concerned, the raw statistics are as follows: 2008, 11 moves; 2009, three moves; 2010, 10 moves. However, the total from 2008 includes passes made because of damage or mistakes, while the 2010 number includes passes by faster cars on a car from the bottom three teams. The number of 'normal' overtaking manoeuvres was: 2008, two; 2009, three; 2010, two.

This year, the number of overtaking moves has not only increased significantly compared to 2010, but it has also risen steadily with each race so far, from 30 total moves in Melbourne (including all types of pass) to 112 in Turkey. Within these totals, the number of 'normal' passes between cars from different teams more than doubled between Melbourne and Sepang, and has since then remained reasonably consistent: the race in Turkey saw 31, for example, compared to 12 in Melbourne and 29 in Sepang. In contrast, the number of DRS-assisted passes has risen significantly, from five in Melbourne to 40 in Turkey. In percentage terms, DRS played a role in 17% of passes in Melbourne, compared to 36% in Istanbul; conversely, 'normal' on-track passes accounted for 40% of passing in Melbourne, and 28% in Turkey.

In terms of passing this year, the raw totals are as follows: Australia, 30; Malaysia, 70; China, 90; Turkey, 112. Within these totals, the sum of 'normal' and DRS-assisted moves is: Australia, 17; Malaysia, 48; China, 53; Turkey, 71. Comparing the raw totals from the 2010 Spanish Grand Prix and the 2011 Turkish Grand Prix, one can see that the race in Istanbul featured over eleven times more overtaking than last year's race in Spain: 112 moves compared to ten.