BOSTON (CBS) — A new concept for longer and lower Green Line cars has been released by the MBTA.

The updated design would be able to almost double the number of passengers that could fit on a single car, bringing the capacity to about 400, according to the Boston Globe.

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A single car would be 116 feet long as opposed to the current 74-foot cars. Similar to the Red, Orange, and Blue Lines, seats would face inward.

According to the MBTA, the new cars will also be 100% accessible because they are lower and will not have any stairs. There will be five doors for boarding.

To get ready for the new cars, the MBTA would need to lengthen station platforms, replace some track sections, and eliminate some sharp turns that are too tight for the longer cars.

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The project is expected to cost $3.5 billion across all four phases. The new cars would arrive in 2028.