The Victorian Government has been accused of pulling up short with its new trams.
The new trams are about 32 metres long, which is two metres longer than some raised passenger platforms built only recently.
The government says it is still working out which routes the new trams will take and which platforms will need to be extended.
The Opposition's transport spokesman, Terry Mulder, says the government has ordered 50 new trams which are two metres longer than some raised platforms.
"In the meantime, if the new trams arrive, the rear door on the trams will have to remain closed and that is going to cause a slowdown and disruption in terms of passengers getting on and off the trams," he said.
Of the thousands of tram stops across Melbourne, 300 are so-called 'super stops' - raised platforms where the passenger can step straight onto or straight off straight off the tram.
Mr Mulder says the super stops were only built a few years ago, and they will need to be extended.
"It should never have occurred. The government should have been aware that there are new trams out there on the marketplace that were longer than the ones that were operating in Melbourne and if they were going to build new super stops, those super stops should have been designed and built to accommodate for any length of tram that Melbourne may use into the future," he said.
The president of the Public Transport Users Association, Daniel Bowen, says it is a case of poor planning.
"Clearly if you have got a standard for tram stops and for trams then you should be sticking to it," he said.
"These platform stops are new. They have all been built in the last few years and a little forward planning, you would think, would have gone a long way towards making sure that all the stops could cope with all the trams."
The new trams are due to be on track by 2012.
A spokesman for the Transport Minister Lynne Kosky says most of the existing stops will be able to handle them and only 20 may need to be extended.
