The problem has arisen becuse of disability rgulations introduced by the government.
Some buses will also have retractable ramps that will make their road clearance even lower.
The regulations have already caused problems in some areas of London where the buses have been trialled and have run into trouble with the 'sleeping policemen' humps. London Transport have begun negotiations with councils to have the humps removed or reduced in height. Until this happens, roads with humps have been declared bus-less zones.
The average cost of installing a himp ranges from£5,000 to£10,000. Replacing them could cost£30m.
A Newham LBC spokesman said the cost of relaying all the borough's road humps would be prohibitive and re-routing buses would be the most cost-effective option. However, the emergency services would likely welcome the lowering or scrapping of the humps.
Ambulances already have to go on special routes to avoid them when transferring critically ill people to hospital if there is a danger a sudden jolt could make their injuries worse.
The DETR has circulated advice to all councils warning them of the problems with the new buses and asking them to take this into account when re-laying humps or planning new ones.