Singapore was the first country to implement congestion charge in 1975, followed by Bergen in 1986, Oslo in 1990 and Trondheim in 1991, London in 2003, and Stockholm in 2007. The majority of existing congestion pricing systems are based on cordon charging, where drivers have to pay for entering or leaving the charging zone (usually the central business district) during the designated time period. Compared to Delhi, all the cities are small (except London), all have very high incomes per capita and all have very well established, dense, attractive and very rich central business districts that businesses are reluctant to leave. All studies show that it takes two or three years to get the technologies ready to establish the charging systems and it is very expensive to do so. The results vary and the London experiment indicates that initially average speeds increased from 14 km/h to 18 km/h in the cordon area. When London introduced congestion charges the average speeds in the central business district were lower than those in Delhi and remain lower after he charges.