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Policy: Carbon AbatementCase Evidence Transport for London estimates that between 2002 – 2003, observable traffic and speed changes have caused a 16.4 % reduction in CO2 emission (TfL, 2006a; TfL, 2007a; EEA, 2008). Estimates by Beevers and Carslaw (2005) over the same period are slightly higher at 19.5% within the central charging zone. Santos and Fraser (2006) estimate that the western extension of the London Congestion scheme implemented in February 2007 could yield a further 12% decline in CO2 emissions. CO2 emissions reduction are less clear for the inner ring road (which surrounds the charge zone). Estimates range between 0.6% by Beevers and Carslaw (2005) to 5% reported by TfL (2006). Moreover, provisional estimates in 2004 suggest continued emissions reductions on the inner ring road (TfL, 2006). However, in 2007 it was reported that there have been increases in traffic flow on the inner ring road with a proportionate increase in CO2 emission of approximately 1% compared to pre-charge levels. This points to the need for capturing potential carbon savings for public transport such as initiatives taken in Sweden with the introduction of fuel cell operated buses (Atkins, 2006; Kakkad and Rossiter, 2007; TfL, 2007; EEA, 2008). Between January and July 2006 a trial run of congestion charging in Stockholm achieved on average a 22% reduction in traffic levels within the charging zone compared to 2005 levels over the same period (Atkins, 2006; CfiT, 2006a; EEA, 2008; OECD, 2008). In Singapore, Electronic Road Pricing (ERP) introduced in 1988 reduced congestion by 13% and increased average speeds by up to 20%. Between 1991 – 2005, Trondheim, Norway’s congestion charge reduced traffic by 10% (CfIT, 2006a). Although exact data on carbon has not been obtained CO2 emissions are closely correlated with the number of vehicle kilometers driven and fuel consumption (EEA, 2008). It is therefore plausible that reductions in CO2 emission can be attributed to less traffic within the charging zone and reduced levels of congestion. Modelling Estimates A study conducted by AEA (2007) on the impact of an emissions related congestion scheme upon the vehicle mix within the London charging zone indicates an increase in band A and B vehicles with potentially related carbon savings. A Transport for London (TfL) model was used to assess vehicles entering and circulating within the charging zone in 2009 based on behavioural surveys conducted by the Halcrow Group . Changes are set against a 2009 baseline without the congestion charging in place. Figure 3-1 illustrates that charging could lead to a reduction in band G vehicles and pre-registered 2001 cars with an engine capacity above 3000cc and an increase in band A and B vehicles by approximately 5% (AEA, 2007).
Figure 3-1. Comparison of passenger car fleet composition for 2009, with and without emissions related congestion charging Source: AEA, 2007 AEA (2007) also conducted life-cycle analysis using the same TfL model. The results suggest that because there is an expected decrease in larger vehicles (band G) and pre-2001 models over 3000cc and a corresponding shift towards smaller vehicles (band A and B) (Figure 3-1) minor CO2 reductions may be achieved. These gains are due to CO2 emissions associated with fuel production and vehicle manufacture associated with a shift from large to smaller vehicles. The largest gains however would be expected from the vehicle use phase of the life-cycle (AEA, 2007). The model predicts that between 0.3 – 2.0% of total CO2 emissions within the charging zone could be abated (representing 1,200 – 8,200 tonnes of CO2) (AEA, 2007). Modelling techniques undertaken for the Sydney Metropolitan Area also indicate a positive relation between congestion charging and carbon savings. For instance, a congestion charge of 50 c/km in the Central City Area of Sydney could reduce total annual vehicle kilometres by 0.43% implying related carbon savings (Hensher and Ton, 2002). Time of Carbon Savings Case evidence from London suggests that carbon savings can be realized over a 1-year period. As stated above various sources indicate that between 2002 - 2003 a 16.4 – 19.5% reduction in carbon emissions was realized within the London central charge zone (Beevers and Carslaw, 2005; TfL, 2006; TfL, 2007b; EEA, 2008). Aside from total carbon savings achieved due to the London western extension, it is reasonable to assume that carbon savings will be realized over a similar time-frame or at least within a 5-year period. Moreover, modelling results across the EU indicate that urban congestion charges could produce remarkable effects during the first years of implementation as compared to the slower penetration of advanced technologies (Zachariadis, 2005). Zachariadis (2005) applies a transport simulation and forecast model to simulate the economic behaviour of consumers and producers within a microeconomic optimization framework over the period 2005 – 2010 applied to 15 European member states. The results indicate that under a scenario where urban travel costs increase over 20% for cars and light trucks, a corresponding increase in public transport use occurs for urban buses and tram/metros by 26% and 14% respectively. Moreover, forecasted improvements in average urban driving speeds particularly in peak hours would lead to fuel savings resulting in a 4.4% reduction in transport energy demand and CO2 emissions by 2010 (Zachariadis, 2005). Modelled results therefore suggest that carbon savings could be achieved within a 5 – year time frame.
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