One in 10 Dublin Bus services will no longer travel directly into the city centre under a proposed restructuring of the network, the National Transport Authority (NTA) has said.
TDs and senators have also called on the NTA to extend the public consultation period on the proposed Bus Connects projects beyond the proposed September 28 deadline, saying it would affect communities across the city, many of which feared losing services.
NTA chief executive Anne Graham told the Dail Transport Committee the new system was designed to provide an improved service, but that some people would be forced to interchange from one bus to another to access their final destination.
She said around 10pc of existing services would no longer travel directly, but this was a "trade-off".
"It's a trade-off in terms of growing orbital services," Ms Graham said.
"We believe it will deliver a better bus service for the city and region.
"It will be easier to understand and provide for better connectivity.
"A review of the network is needed. There will be a 27pc increase in bus services.
"Not everybody can be better off under the network, but the vast majority of people in the region will benefit."
Dublin Bus completes around 136 million trips every year, and there was a concern that those living in outlying areas would lose most, Social Democrats TD Catherine Murphy said.
"You said there was winners and losers and there are some very big losers in this," she said.
"You want to discourage the car user and make the bus service more attractive, but what I see is the real losers are on the fringes.
"There's way too much detail which is absent. The closer you get to the city, the greater the gain is. The further from the city, it's more attractive to use your car."
Among the issues raised at the committee were the relatively short window for the public consultation process, which could be extended, the NTA said.
Also raised were the impact on lower-income groups, questions about how the elderly and people with disabilities would access services, the number of passengers who would be required to interchange and the location of interchange stops.
Separately, the committee heard that construction of the MetroLink will result in a "Berlin Wall" being erected through south Dublin.
The Rethink MetroLink Dublin South City group said the high-speed line will close roads and pedestrian crossings in Ranelagh and Rathmines, add to safety risks for cyclists and affect families with young children and those with disabilities.
It has sought a meeting with the NTA on the project.