Federal transportation officials committed Tuesday to funding a $1.3 billion grant for a project set to bring subway service to Los Angeles’s Westside.

That money is expected to cover more than one-third of the total cost of the third and final phase of Metro’s D (formerly Purple) Line extension, which will add two new train stations and 2.5 miles of track to the rail line.

Once complete, the elongated D Line will carry riders from Union Station to the Veterans Affairs campus at the base of Brentwood—a trip that can sometimes take more than an hour by car—in under 30 minutes.

This potentially game-changing transit line has been in the works for at least two decades, and the long-awaited federal funding announced Tuesday ensures it stays on track to open before this decade ends.

But the first part of the line is already open, and has been since 1996. And with the first phase of the extension expected to open in just a few years, Metro is preparing the train line to handle an influx of new riders.

Whether you’re a new rider or a Metro pro, here’s a guide to the D Line—and the big changes in store for the train.

Where does it go?

Right now, the D Line runs about 6 miles between Downtown LA and Koreatown, stopping in Westlake along the way. It stops at eight stations total and shares track with the B (formerly Red Line) for six of those stops.

The two lines diverge at the Wilshire/Vermont station in Koreatown. At that point, the Red Line hooks north toward Hollywood, while the D Line continues west to stops at Wilshire/Normandie and Wilshire/Western.

What places can you get to from there?

In Downtown LA, the D Line passes through the Civic Center, Historic Core, and Financial District—offering easy access to the El Pueblo de Los Angeles Historical Monument and Olvera Street, City Hall, Grand Park, the Los Angeles Music Center, the Museum of Contemporary Art, Pershing Square, Grand Central Market, the Angels Flight Railway, the historic theaters of Broadway, the Broad Museum, the Los Angeles Public Library, the U.S. Bank Tower, and the Wilshire Grand.

To the west, the train also stops near MacArthur Park and the Wiltern Theatre, as well as the many historic buildings and tasty restaurants that line the Wilshire Corridor.

How often does it come?

The D Line runs roughly between 4:30 a.m. and 1 a.m. on weekdays. On Fridays and Saturdays, the line runs later, until about 2:30 a.m. Trains are scheduled to arrive at intervals between 10 and 20 minutes on weekdays, coming more often during peak morning and afternoon commuting hours. On weekends, they come every 12 to 20 minutes, with more frequent arrivals in the middle of the day.

Riding Metro Fares: All Metro trains and buses cost $1.75 for a one-way ride (which includes free transfers to other lines for up to two hours). How to pay: To board trains, you’ll need a TAP card, which can be purchased at any rail station and from vendors around LA County. TAP cards can be loaded with a stored dollar amount or can be purchased in the form of a monthly, weekly, or daily pass. Discount programs: Metro offers several discounted options for students, seniors, and people with disabilities. There’s also a subsidized fare option for low-income riders.

When will the line be extended?

The extension is set to be completed in three phases (though work on all three is happening simultaneously).

The first will bring the line west through Mid-Wilshire to the eastern edge of Beverly Hills at Wilshire and La Cienega boulevards. Already more than halfway complete, it’s expected to open in 2023.

Construction on the second phase started in 2018. Still running mainly along Wilshire Boulevard, this segment will go through the heart of Beverly Hills, ending up at the intersection of Constellation Boulevard and Avenue of the Stars in Century City. It’s scheduled to open in 2025.

The third phase will bring the line to the Veterans Affairs campus just west of the 405 freeway, with a stop near UCLA in Westwood along the way. Metro expects to complete this segment by 2027 (the full extension is one of 28 projects the agency aims to wrap up in time for the 2028 Olympics).

Taken together, these three project segments will add seven new stations and 9 miles of track to the D Line, more than doubling its current length.

Wait a minute, wasn’t this supposed to be a “subway to the sea?”

Los Angeles officials once envisioned a project that could whisk riders from Downtown to the beach, but Metro ultimately balked at the costly and complicated prospect of tunneling all the way to the coast. Instead, the E (formerly Expo) Line was extended from Culver City to Santa Monica, providing riders with a scenic, but mostly above-ground, connection to the ocean.

How long will the ride take?

A trip along the entire 9-mile extension is projected to take about 15 minutes. Add that to the 13 minutes that a ride on the existing line lasts, and that’s roughly a 28-minute trip.

Will the schedule change?

As construction moves forward on the three segments of the D Line extension, Metro is also working on a separate project that will allow B and D Line trains to move in and out of Union Station more efficiently.

A new turnback facility bordering the Arts District would allow 30 trains to pass through the station every hour, greatly diminishing wait times for riders. During peak hours, Purple Line trains could arrive as frequently as every four minutes.

The agency may need to run more trains to keep up with demand. Metro projects that just the seven new stations on the full extension will attract nearly 50,000 riders every weekday. The project is expected to result in 78,000 new daily trips across the whole system.

What will the new stations look like?

Since it’s a subway, the extended Purple Line will be an all but invisible addition to the city for those who don’t ride it. But the station entrances will be above ground, and Metro has released renderings of all seven new stations on the project website.

Seen above is the Wilshire/Fairfax station, which Metro originally planned for the northwest corner of the intersection, close to Johnnie’s Coffee Shop. After some lobbying from LACMA, however, the station entrance has been moved to the south side of Wilshire at the corner of Orange Grove Avenue—across the street from the museum. LACMA has also agreed to finance a second entrance on its side of the street.

As with all Metro stations, the new stops will include unique art installations

What other lines connect with it?

The D Line already links up with the A (Blue), B, E, and L (Gold) lines, so transferring to the route is easy to do. Once Metro’s Regional Connector project wraps up in 2022, the A, E, and L lines will merge and become two lines rather than three. Both will connect to the D Line at Union Station and the 7th Street/Metro Center station in the Financial District.

Further on in the future, the D Line could also intersect with the under-construction Crenshaw/LAX Line and a proposed transit route through the Sepulveda Pass.

Metro also aims to have the latter project done by 2028, though it’s still very much in the planning stages. Extending the Crenshaw/LAX Line north of the Expo Line, where it will initially end, will take a little longer. That project has a projected 2047 completion date, but West Hollywood officials are pushing to move the project forward sooner.