Metro does not have bumpy tiles along the edges of nearly a quarter of its platforms, despite a more than 20-year-old push for the transit agency to install them at all stations to help prevent visually impaired riders from falling onto the tracks.

The agency plans to install some tiles with bumps, known as truncated domes, at 10 more stations by mid-2015, during other major station repairs. But an estimated $6.6 million hasn’t been set aside in Metro’s $5 billion rebuilding campaign for the remaining 11 stations.