CONCERNED headteachers at two schools say plans to merge separate bus routes into one won't work.
The heads of the Dr Challoner's schools in Amersham and Little Chalfont say the plans will worsen congestion problems and leave pupils with longer journey times and waits at the end of the school day.
Ian Cooksey, headteacher at the High School for girls, added he was not told about the planned changes by Buckinghamshire County Council but instead heard the news via one of the bus contractors who contacted the school to ask if the new scheme was workable.
At the moment each school is served by its own route - but the council plan would combine these and 16 double decker buses would head firstly to the High School before turning round and heading back to the Grammar School in Amersham.
But in a letter to parents outlining his concerns, Mr Cooksey said: "The council accepts that many routes will be significantly longer, with a planned duration of one hour becoming the norm. With the degree of slippage in the schedule which we believe is likely to occur, many journeys will approach the legal maximum of 75 minutes.
"Many students are likely to drive almost literally past their own school and then face a further journey time of up to 30 minutes each day. The amount of time which students spend waiting for buses is also likely to increase, particularly at the Grammar School site at the end of the day.
"By law, school buses have to depart within 30 minutes of the end of the school day and we believe that this is likely to be breached on a regular basis under the new arrangements."
Mark Fenton, headmaster of the Grammar School, said: "If the boys come in from somewhere like Prestwood you can pass through Amersham, past the school, through the heavy traffic and back again. It will add another half an hour onto journeys as a matter of routine, and that's assuming it works to schedule."
He added there would not be enough space for 16 buses and they would back up onto the roads around the school, increasing congestion.
Dr Fenton said one of the buses collecting pupils already has to queue in the car park as there is no officially designated bay for it, and there are no shelters for students who could potentially have to wait around for half an hour at the end of the day.
He has written to residents of adjacent Longfield Drive to get their views and raised the issue with the school's student senior leadership team.
Year nine pupil Matthew Goodwin-Freeman, 14, said: "The main problem is that at the front of the school there isn't enough space to have 16 double decker buses.
"At the moment it's like a military operation trying to get everyone on the right bus at the right time and leave.
"If one at the front is taking longer to fill up then the ones at the back will be stuck.
"It would make more wrongs than it would solve rights."
Mike Appleyard, Buckinghamshire County Council's Cabinet Member for Education and Skills said: "We are currently in the phase of collecting information to decide whether the proposals are viable or not. We have not made any decisions.
"However the council is having severe difficulties balancing its budget, costs are going up and the government restricts our ability to increase council tax, so we have to look at all options to see which areas of savings can be supported."