I'll kick it off with an example. This is Sarbanes Station
, aka the Silver Spring Transit Center
, in downtown Silver Spring, Maryland. It is currently under construction.
It's being built adjacent to the existing Silver Spring Metro station, which is the busiest DC Metro station in Maryland. The Metro station won't change, but the new transit center will integrate a large regional bus station with separate areas for local, commuter, and intercity buses. It will also provide improved connection to the existing Silver Spring MARC commuter rail station, and add a new elevated light rail station for the Purple Line, which hasn't been built yet. It will also have a taxi stand, a bikesharing station, direct access to a major regional bike trail, and an attached commuter store.
This image shows the existing Metro station in the lower right corner, with the existing MARC station behind it in the upper right. The new building is the curvy concrete one, which will have three levels. The top level is a taxi stand (the building is on a hill so the top level is actually flush with the ground at the rear of the site), the middle level is for intercity buses, and the bottom level is for local buses. This image is missing the light rail station, because it will be added later.
Here's a similar view. The small unlabeled building on the sidewalk in the lower center is the commuter store.
This image shows how the Purple Line light rail platform will be added. It will be elevated directly above the trail and commuter store, in the space between the bus garage and Metro station.
The design for Sarbanes Station that was ultimately chosen and is currently under construction was the 3rd version. Unfortunately, the previous 2 were better.
This was the original design, from the late-1990s. It was much more grand, as you can see. The problem with this design is it did not integrate light rail. The light rail station that will be built is located exactly where the grand stair is in this version.
In the early-2000s, this 2nd design was proposed. It would have had a large central atrium waiting room. This was eventually abandoned because, I think, cost.