The Metropolitan Police has warned its response to emergency calls is being hampered by road humps.
There are up to 30,000 speed bumps in London
A traffic division report accused councils of implementing traffic calming in roads which have no history of accidents.
In the last three months 34 police vehicles were possibly damaged due to traffic calming features, it added.
The report called for a new strategy to make sure traffic calming features are standard across London.
The disclosure comes after the head of London Ambulance Service called for a review of speed bumps, saying they put patient's lives in danger by slowing emergency response times.
It has been estimated that there are between 20,000 and 30,000 speed bumps in London, with thousands more ramps, barriers and chicanes.
The traffic division report said that road humps encourage drivers to speed up in the gaps between them.
It adds: "Traffic calming does affect attendance times, based on the principle that any highway obstruction will impede the progression of the emergency services during a response call."
It also said there was "little evidence" London boroughs have acknowledged the importance of identifying and agreeing upon strategic routes for emergency services.
The study has been submitted to the London Assembly's transport committee, which is due to meet next week.
Transport for London has said in the past that road humps were a key factor in reducing fatalities on the roads.
But Brian Coleman, Conservative London Assembly Member, said: "We already know from the London Ambulance Service that so-called 'traffic calming' causes over 500 deaths a year in London alone, and now the police have confirmed it affects their response times too.
"The evidence is clear - road humps are a menace which are endangering Londoners. "