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Network & Environment


TfL acknowledges that it is difficult to separate out the direct impact of the Congestion Charge itself on the function of the road network. Improvements to the road network can be attributed to the impact of a wider package of measures, including major projects such as the pedestrianisation of Trafalgar Square, which removed traffic from the northern side of the square in order to improve the urban environment.
Table 2 2 observes the key percentage changes year on year in traffic entering the central London charging zone between 07:00 and 18:30 . The column 2003 vs 2002 shows the immediate impact of the introduction of Congestion Charging in 2003. The gradual variations year on year are also shown as well as the overall change in the last column of the table that compares 2006 with 2002.

Table 2 2 - Key year on year changes in traffic entering the central London charging zone during charging hours (07:00 – 18:30) .

Statistics of note in the above table include the number of cars and minicabs entering the central London charging zone. During charging hours in 2006 this was 36% lower than 2002 i.e. before charging was introduced. Alternatives to car travel such as pedal cycles have become very popular – a 49% increase between 2002 and 2006.

In terms of network speed, TfL notes a fluctuation over time since the introduction of Congestion Charging in 2003. The figure in 2003 was approximately 17 km per hour, compared to 14 km per hour in 2002. More recently, observed charging hour speeds have fallen to 16 km per hour in 2005 and 15 km per hour in 2006. TfL say that modeling suggests that had charging not been introduced, average speeds would have worsened from the 14 km per hour figure in 2002, to approximately 11.5 km per hour by 2006.

The effect of the western extension on traffic volumes and traffic composition is in line with Transport for London’s expectations. Their July 2008 impact monitoring report records that traffic entering the extension zone during charging hours in 2007 (vehicles with four or more wheels) was down by 14%. This level of reduction has been preserved in 2008, and compares with TfL’s expectation for reductions in the range 13 to 17%. Details of modal split are contained in the table below.

Table 2 3 – Traffic leaving the western extension zone across all outbound roads. (Charging hours, 07:00 – 18:00, 2005 to 2007)


After the introduction of Congestion Charging in 2003, TfL expected a reduction in congestion of approximately 20 to 30%. A 2002 baseline value of 2.3 minutes  per kilometre was established.
Surveys of the Central London charging zone in 2003 indicated average delays  were about 1.6 minutes per kilometre - a reduction of 0.7 minutes per kilometre, compared with the 2002 baseline, a reduction of 30%. Subsequent years recorded a 30% (2004) and 22% (2005) reduction, compared with the 2002 pre-charging
baseline. During 2006 congestion reduction fell to 8%, while in 2007 congestion returned  to the levels experienced in 2002. This was not due to a rise in traffic levels,  which remain relatively unchanged. It is thought the increase was caused by  other factors, in particular a notable rise in the street works projects that  have affected capacity on the road network and thus traffic flow.

Public Transport network


Bus patronage figures for passengers entering Central London increased year on year between 1999 and 2002 – from approximately 70,000 passengers in 1999 to just below 88,000 passengers in 2002. There was a significant increase in 2003 to approximately 104,000 passengers, and a further rise to 116,000 in 2004. Patronage stabilised at around 116,000 in 2005 and 2006.

The Underground

The Underground has seen less of a significant impact on patronage since 2003. A recorded average of approximately 516,000 passengers exited stations in and around the central charging zone during the morning peak period in 2002. This rose to 523,000 in 2006 having been 498,000 in 2005.


The impact of the Charging Scheme on the environment is arguably best measured by changes in vehicle emissions and measured air quality. It is challenging to attribute the direct impact of the Charging Scheme on either in isolation.

There have been a number of factors, unrelated to Congestion Charging, which have had an impact on air quality, not least technology changes to vehicles and most recently the introduction of the London Low Emission Zone.

However, the improvement in air quality – reducing emissions to air – has been due in part to less traffic moving within central London and that which remains in the area moving more efficiently.

Table 2‑4 summarises the key percentage changes between 2002 and 2003 - before and after the introduction of the Congestion Charge in Central London.

Table 2 4 - Principal changes to emissions of NOX, PM10 and CO2 .


Former London Mayor Ken Livingston had proposed to introduce a higher daily levy - £25 (€30) compared to the current £8 (€9.60) charge – for high emission vehicles in the Autumn 2008. With the recent change in administration in May 2008 and new Mayor of London, Boris Johnson taking charge, this proposal has now been abandoned.

Table 2‑5 summarises the key the percentage changes to emissions inside the Western extension zone between 2006 and 2007.

Table 2 5 - Principal changes to emissions of NOX, PM10 and CO2 in relation to the western extension. Percentage change, 2007 compared with 2006. Annual average day, all road traffic emissions .

Source: Transport for London