AC Transit is pushing ahead with its plan to turn the two center lanes of traffic into separate bus-only lanes on Telegraph Avenue, International Boulevard, and East 14th Street. The agency’s Bus Rapid Transit plan would shrink permanently from four to two the number of lanes for vehicle traffic from downtown Berkeley to the San Leandro or BayFair BART stations. The BRT line would extend to Shattuck Avenue and be 15 to 17 miles long, depending on which of the four possible routes AC Transit ultimately chooses.

AC Transit and supporters argue that the $250 million to $400 million proposal is the best way to convince more East Bay residents to get out of their cars, increase bus ridership, and diminish carbon-dioxide emissions. AC Transit officials say the plan will speed up bus commutes and boost the number of weekday trips from 4,600 to 9,300. Backers of the plan also say it will help spur additional transit-village-like developments.

Proponents also argue that dedicating two lanes to buses will quicken bus-commute times, making AC Transit more attractive for commuters and others. The agency also plans to speed up commute times by allowing riders on these lines to prepurchase tickets at kiosks located on station platforms in the middle of the streets.

But opponents argue that cutting car and truck traffic down to one lane in each direction on three of the East Bay’s major transit corridors will result in nightmarish gridlock. They say motorists will undoubtedly take shortcuts to avoid the massive backups, sending rush-hour traffic onto normally quiet neighborhood streets.

The 31 to 51 center-of-the-street station platforms occupy too much space to accommodate curbside parking in the vicinity, which would result in the elimination of between 945 and 1,300 total parking spaces. In addition, two of the four proposals call for non-rapid buses to share the single north and southbound lanes that is to be used by all other vehicles.

AC Transit has already invested heavily in the BRT-type buses. Since 2002, the agency has spent more than $100 million on 233 European-style rapid buses it purchased from a Belgian manufacturer. The agency also has suffered tough economic times in recent years, cutting bus service by nearly 30 percent as ridership has stagnated.

The transit agency is currently finalizing its environmental impact report. The project requires the approval of Caltrans, the state highway department. The project does not require the official approval of the cities of Berkeley, Oakland, and San Leandro, but AC Transit officials say they will not go forward with the project if the city councils of one or all of the cities come out against it.