In an ambitious attempt to reverse the traffic growth that is choking Britain's cities and clogging its highways, the government announced broad plans to impose new taxes on cars entering crowded urban areas, bolster spending on bus and rail services and even encourage parents to walk their children to school. John Prescott, deputy prime minister and minister for transportation, said Britons needed to radically change the way they travelled to work, schools and shops to avert national gridlock in the 21st century. Road traffic has doubled over the last 25 years and could rise by a further one-third in the next 20 years without reform, he said.