Loudoun County officials wondering whether they should pull out of the second phase of the Dulles Metro rail project were told Tuesday that they would save hundreds of millions of dollars if they did. But if Loudoun wanted to replace the rail line with a cheaper bus system, most of those savings would be lost.

The second phase of the Metro rail project includes two stops in Loudoun County. Eliminating those would cut $530 million from the second phase’s $2.8 billion cost, the Dulles Corridor Advisory Committee learned Tuesday.