Several groups oversee Metro’s safety and operations in some regard — but experts say none has total authority or the ability to enforce their standards.

» National Transportation Safety Board: The independent federal agency is investigating the June 22 Metro crash but makes recommendations after the fact. Even then, the transit agencies do not have to follow them. In 2006, the NTSB told Metro to replace or retrofit its 1000 Series railcars, which were involved in the latest accident, saying they were not “crashworthy.” Metro did not do so and says it would cost nearly $900 million to replace more than one-quarter of its fleet.