There are four designs Caltrain wants you to vote on. One of the designs will be chosen for the new electric fleet, to replace the current diesel trains.
The agency says the new system will increase capacity, improve train performance, and offer a quieter ride.
"By converting Caltrain from a diesel-based service into an electrified system, we'll be reducing regional traffic congestion and greenhouse gas emissions," Caltrain said in a video.
But the project has hit a bump. Transportation Secretary Elaine Chao is holding up a $647 million federal grant.
Electrification supporters point out California's Republican Congressional Delegation is opposed to electrification because it paves the way for the state's high-speed rail, something they oppose.
Click here to choose your favorite design. Voting is open on the Caltrain site until midnight on Friday.
Click here for more stories about Caltrain.
Watch Kristen Sze's full report starting at 4 p.m. on ABC7 News.