What is the capital of Texas? Austin. But only politically. Texas has no true capital in the sense of London or Paris — we have several major metro areas, and no single one dominates.

What is the center of Houston? Downtown, perhaps. But not really. There’s more retail in the Galleria, more health care in the Medical Center, and new centers growing up in places like the Woodlands. Houston is a metropolitan area with multiple centers, and it’s getting more so.

So how do we build transit for a place with many centers?

Here’s a clue. This is a swatch of Germany, one of the most multi-centered countries in the world. At the top is Frankfurt, and at the bottom is Stuttgart. Here’s what the map shows:

• Black lines are the national passenger trains network, the DB. The thin lines are branches, served perhaps by a local train every hour or two. The thick lines carry not just local trains but intercity and international trains, to places as far away as Paris and Warsaw.
• Green lines are commuter trains, called S-Bahn in Germany. The S-Bahn connects major cities to nearby cities and the suburbs. These run all day, every day, every 15 minutes to half an hour. For the most part, these systems use the same tracks as DB trains. In Frankfurt and Stuttgart, though, they run in subway tunnels in the city center. In Karlsruhe, the S-Bahn is operated using light rail vehicles which share tracks with DB trains on most of the system but run on city streets in Downtown. Here we see four of these networks; three are connected at their outer ends.
• Blue lines are light rail, called U-Bahn, serving city cores, outer neighborhoods, and inner suburbs. Both Frankfurt and Stuttgart have light rail systems that run in subway in the center, then in reserved lanes further out.
• Red lines are streetcars. They use the same technology as light rail, but to a different end: they run in city streets to serve close in neighborhoods and circulate people in the core. In this region, there are six such networks, in addition to two suburban lines that use the same urban networks.

Why use four different rail systems? Because they all serve different purposes. The Germans have concluded that a light rail system isn’t suited for getting you to a different city, and a commuter train system isn’t suited for getting you from one urban neighborhood to another.

But the key is linking these systems. The white dots on map are high speed rail (PDF) stops, and almost all of them are also major intermodal hubs, usually located at downtown train stations. Here’s one, at Frankfurt Hauptbahnhof:

All of the different modes I’ve mentioned are here. Transferring from one to the other is simple. Once you arrive at this hub, you can get anywhere in Frankfurt easily. This isn’t the only hub like this. Every city center on this map has one. So do the airports: Frankfurt airport is served by S-Bahn trains to Frankfurt and to other local cities like Mainz and Wiesbaden. It’s also served by high speed trains to German cities like Stuttgart, Cologne, and Hamburg and international trains to Vienna.

But while the system is set up to make transfers easy, it’s also designed to minimize them. There was already a streetcar line from the Hauptbahnhof into Downtown (PDF) when the S-Bahn opened, but planners didn’t want to force transfers. So the S-Bahn keeps going, diving into its downtown tunnel and stopping right where the jobs and the stores are. Multiple systems run parallel, providing different kind of service.

Perhaps the most important part of the system doesn’t show on the map. Consider the immediate Frankfurt area: there are half a dozen different agencies operating rail transit. But the passengers don’t need to care about that. You can ride light rail in Frankfurt, transfer to the S-Bahn, ride to Mainz, and get on a streetcar for the end of your trip (PDF), all with a single ticket. That’s three different operators, but there’s one blanket agency that coordinates ticketing and rider information.

Here’s the kicker: this map covers about the same area as the greater Houston region. Here’s the comparison:

Like the Frankfurt area, we’re a region of multiple centers. Of course, we don’t have nearly the same transit system. But our system is growing. We should take some lessons:

• Provide multiple systems to meet multiple needs. Don’t make suburban passengers ride through 12 stops to try to serve urban passengers as well. And don’t make urban passengers walk out of their way to a station so that the trains can run faster for the suburban passengers.
• Link systems. Wherever two transit systems meet, there should be an easy connection between them. And at key places there should be important nodes that bring all the systems together.
• Make the experience seamless for the passenger. Put all of the systems in one online trip planner. Make sure the person sitting at the ticket window in the transit center has all that information as well. And sell the passenger one ticket for their entire trip.

In a few years, it may be possible to do the same kind of light rail-commuter rail-streetcar trip I described above in traveling from Houston to Galveston. Will we make it as easy?

Tell us in our forums.