They're 45mm. So like a coke can in diameter. Speed bumps - which are everywhere - are allowed to be up to 100mm: https://www.legislation.gov.uk/uksi/1999/102

They're 45mm. So like a coke can in diameter. Speed bumps - which are everywhere - are allowed to be up to 100mm: https://www.legislation.gov.uk/uksi/1999/1025/regulation/4/made https://www.legislation.gov.uk/uksi/1999/1025/regulation/4/m.... I drive over speed bumps all the time and they're more than twice the height.