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Another day, another ranking: The percentage of D.C. households without a car grew the third-fastest among America’s 30 largest cities between 2007 and 2012, reports Streetsblog. That’s all the more impressive considering that D.C. was already the city with the second-most car-free households in 2007. Now, nearly two in five households in the city do not have cars.

But that figure could be even higher, and those car-free households better served, if not for consistently flawed assumptions by the government. Consider these two examples of the faulty projections that are putting too many dollars into suburban infrastructure and not enough into cities and public transit.

First, a chart posted yesterday by Matt Yglesias, from a report last month by the State Smart Transportation Initiative:

The colored lines represent the U.S. Department of Transportation’s forecasts in various years of the increases in vehicle-miles traveled—-in other words, how much people are driving. The black line is the reality. In other words, the actual amount that people drive keeps falling short of the DOT’s projections, yet the DOT keeps on projecting that it’ll grow at the same rate it’s been projecting. In the last few years, as driving has actually declined, the DOT has kept its growth forecasts exactly the same. These forecasts, naturally, influence the federal government’s allocation of transportation dollars to highways and transit projects, and favor the highways.

Second, Ben Ross recently highlighted the problematic system used to plan the future of the D.C. Metro at Greater Greater Washington. In proposing an expansion of Metro for 2040, the Washington Metropolitan Area Transit Authority considered and rejected several ideas that would have served District commuters, like a Brown Line with stations in Bloomingdale and Brightwood. Instead, it adopted a plan that offers new downtown and suburban connections, which will make life easier for many people working downtown, but particularly for Virginians. And the new line that’s actually being built right now, the Silver Line, adds stations only in Virginia.

Why is Metro’s expansion so focused on suburbanites? Ross says the answer has a lot to do with the fact that WMATA is required to base its plans on the Metropolitan Washington Council of Governments’ official land-use forecast. “This forecast, in practice, is prepared by cobbling together the master plans adopted by local governments, which are not anyone’s best guess of the future, but mostly reflect the desires of locally dominant political forces,” Ross writes. The reasons are complicated—-they have to do with zoning and politics—-but the effect is a skewed projection of who will need more Metro service. The official forecast, Ross says, predicts 95 percent population growth in Stafford County by 2040, and just 28 percent growth in D.C., whereas the District is actually growing faster.

Yes, D.C. and the surrounding jurisdictions are growing less reliant on cars. But they’re also up against a stacked deck. If the various federal and regional and local government entities were working off better projections, the expansion of urban transit might be happening a lot faster.