In some circumstances of urban operation (such as in areas with narrow streets and tight turns), articulated buses may also be involved in significantly more accidents than conventional buses. Estimates for London's articulated buses put their involvement in accidents involving pedestrians at over five times the rate of all other buses, and over twice as high for accidents involving cyclists. In a period when articulated buses made up approximately 5% of the London bus fleet, they were involved in 20% of all bus-related deaths, statistics which eventually led to their replacement.[13] However, these safety statistics may be partly skewed due to the buses having been used on the busiest routes in the most crowded areas of the city, making them look worse than the buses they were being compared with.[14]