Motoring organisations believe the Stillorgan "Quality Bus Corridor" will make Dublin's traffic problems worse.
"There is a huge difference between a QBC and a bus lane, and it is precisely because we are getting a bus lane instead of a QBC that there is such an emotive response," Mr Conor Faughnan said.
The AA spokesman said those promoting the scheme were determined to target motorists without giving them any realistic alternative. He predicted enormous delays.
A QBC, he explained, was defined in the Dublin Transport Initiative (DTI) report of 1994 and was welcomed by the AA. He insisted the AA is still very much in favour of the QBCs "as originally outlined".
The report envisaged converting motorists to public transport through a number of measures, such as high-frequency buses along the corridor, with feeder buses taking commuters to the corridor from other areas.
It dictated that the form of transport offered as an alternative to motorists should involve a "stylish, comfortable, environmentally-friendly bus" with a high level of service, both from staff and machines.
It also said there should be integrated ticketing: if you are to travel from Dundrum to Drumcondra, thereby changing buses, you should be able to buy a through ticket on the first bus.
Similarly, if you need to get off the bus at any stage, to ensure the children get safely to school, for example, you should be able to get on the next without having to buy another ticket.
There should also be interchange facilities for those who get a feeder bus to the bus corridor, with weather-proof shelters. Bus information displays should be in "real time" at each stop to give customers immediate information on the availability of a bus.
But most importantly, in terms of enticing commuters from their cars, there should be park-and-ride sites.
Mr Faughnan said many driving into Dublin along the Bray-Stillorgan route would transfer to a bus if there was somewhere to leave the car.
He said enormous delays were in store, with motorists being squeezed off the road and given no alternative.
"If they could, say, go and use the park-and-ride sites at Foxrock or at Belfield then we would say, OK, it is a QBC, but it is not. What is happening is that the motorist is being seen as the problem and anything that is bad for them is a good thing," he said.
Mr Faughnan added that the bus lane, as opposed to a QBC, was simply a strip of roadway and some changes at intersections where buses had priority.
"We are being given a bus lane on the Bray Road. It is giving priority to buses by just forcing motorists off the road, and it is being sold as a QBC," he said.
He said two previous QBCs were on the Lucan and Malahide routes, which were dual carriageways until they got very close to the city and traffic had dispersed. Traffic on the Bray Road, however, tended to go all the way to St Stephen's Green before dispersing.
Mr Faughnan said it was important, however, to realise that the AA did not want the QBC shelved; simply that before it operated there should be park-and-ride sites to enable existing car-users to switch; integrated ticketing; quality bus shelters displaying "next bus" times and stage times, proper timing for buses rather than just arrival and departure time at the terminus.
"In the dark mornings of autumn and winter the tailback for traffic entering Donnybrook village in the mornings routinely reaches back to RTE. Cut the capacity of Donnybrook in half, as the bus corridor is set to do, and that tailback will reach beyond UCD, increasing journey times for that two-mile stretch of road from 30 minutes to 50 minutes," he said.
Other motoring organisations have also criticised the planned QBC. Mr Cyril McHugh, of the Society of the Irish Motor Industry (SIMI), said the move was designed to "punish Dublin motorists and frustrate traffic".
He added that the Dublin Transport Office was taking the cheapest option and painting a white line on the road.
