I n the wake of Larry Hogan's election as governor, Maryland has been inundated with propaganda claiming the Purple Line light rail from Bethesda to New Carrollton will do everything from relieve congestion to revitalize the economy. This is all hogwash.

Light rail is slow, expensive, low-capacity transit that will burden Maryland taxpayers for decades to come. Projections made for the line suffer from what planners call "optimism bias," meaning they are designed to make a bad project look good. Yet even if you believe the numbers, they don't justify the cost.

The original cost projection for the line was about $1.7 billion. The price has now risen to $2.4 billion and will probably go higher. Even at the lower cost, the state's alternatives analysis showed that buses were far more cost-effective at moving people than rail.

The projected 2040 ridership for the line of more than 69,000 daily trips is three times greater than the average light-rail line in the country. Transit ridership is a function of population and job densities and most other light-rail lines serve areas that are much denser than the Purple Line corridor.

New Jersey's Hudson-Bergen light rail serves an area that has four times the population density of urban Montgomery County and a job center with 123,000 jobs, far more than any point on the Purple Line. Yet the Hudson-Bergen line carries only 44,000 trips a day.

The state's ridership projections for Baltimore light- and heavy-rail lines all proved to be two or more times greater than actual ridership. If built, the Purple Line will be no different.

One reason ridership will be low is that trains would be slow. Purple Line trains are expected to average less than 15.5 miles per hour — and that, too, may be an optimistic prediction.

Even if you believe the optimistic ridership numbers, the Purple Line will cause more congestion than it will relieve. The traffic analysis for the draft environmental impact statement (EIS) predicted building the Purple Line would slow average regional traffic speeds from 24.5 to 24.4 miles per hour. Multiply that by the amount of projected traffic and the line will waste 36,000 more hours per day in 2030 than if the line isn't built.

Nor is light rail good for the environment. The draft EIS found trains would use more energy than all the cars they would take off the road.

Proponents claim the Purple Line will stimulate economic development. In fact, a study funded by the Federal Transit Administration found "rail transit investments rarely 'create' new growth, but more typically redistribute growth that would have taken place without the investment."

Urban areas that spent the most, per capita, on transit capital improvements in the 1990s were among the slowest-growing regions in the 2000s, while the ones that grew fastest were among those that spent the least. The tax burden of rail transit does more harm to the economy than good.

The Purple Line is nothing more than corporate welfare for contractors and railcar manufacturers. The best way for Hogan to revitalize Maryland's economy is to cancel the Purple Line, Baltimore's Red Line and similar boondoggles.

Randal O'Toole is a senior fellow with the Cato Institute, a visiting fellow with the Maryland Public Policy Institute and author of "Gridlock: Why We're Stuck In Traffic and What to Do About It."