Former Editor-in-Chief Ryan Avent writes a weekly column about neighborhood and development issues.

It’s easy to focus on the problems and pathologies at the margins of a rapidly growing city. The pains of congestion and growth are frequently more dramatic in the far flung counties, where populations increase annually by astounding percentages and where infrastructure is least developed. At some point, though, you have to realize that one of the best ways to fix the problems at a city’s margins is to keep improving life at the center. If we want to help reduce the pressure to expand, we’ve got to make sure that we keep things running smoothly at the heart of the metropolis.

At the moment, we are not doing the things that are going to allow that to happen over the long-term. It’s nice to think that at some point density and transit might make their way into Prince William County, and it’s fantastic to imagine taking Metro out to Tyson’s or Dulles Airport, but gains made on the transit periphery will be next to useless without a functioning core. As cost estimates for Metro expansions outside the Beltway run into the billions, those same expansions have their value undermined by trains inside the Beltway that slow down and break down under the crush of intense use.

Last year, transit ridership nationwide hit a 40 year high, and Metrorail use has followed a similar trend, growing steadily and constantly over the past decades. On most weekdays, Metrorail easily tops 700,000 daily riders (along with over 400,000 daily Metrobus users), and 2006 alone was responsible for seven of the system’s ten highest ridership days. It’s probable that the coming spring and summer seasons will set additional records.

It’s difficult to imagine what a typical summer weekday might look like without any rail service at all (and it’s scarier still to imagine what might happen to downtown, the third largest central business district in the nation, if rail were offline for an extended period), and yet practically nothing is being done to arrest the growing paralysis on what is an extremely successful but woefully underdesigned transportation system. Metro should be running more trains, more often, for longer hours, but instead finds itself having to reduce capacity to address maintenance needs. When an unexpected incident occurs, the system rapidly bogs down into single-file lines of immobile cars filled with irate passengers. Metro will be able to get along for a short time without any major improvements, but upgrades and expansion take time. If we’re not yet beginning the process of adapting to a busier future, what are we waiting for?