notes.husk.org/likes images.

BART ridership will reach half a million daily riders within the next decade and about a third will enter and exit San Francisco’s Montgomery and Embarcadero stations.

They sit on the San Francisco side of the Transbay Tube and the time it takes to board a third of their passengers limits how frequently trains can pass through the tube.

> “[T]o speed up the trains, BART needs to relieve the bottleneck in the Financial District stations. Any big glitch in the system, and the platform gets so crowded now at rush hour that service can actually slow down, as operators wait for the crush of people to sort themselves out.”

BART is considering building additional boarding platforms on the outside of the two existing stations that would let passenger board from both sides of the train. New elevators and entrances will also be added, otherwise the bottleneck would move just move across the platform from the trains to the exits.

With the additional platforms BART would be able to increase capacity in the underwater tunnel from 24 trains and hour up to 30.