WASHINGTON (AP) — The railroad industry is playing down expectations that a safety technology that could have prevented recent deadly train crashes will be in operation across the United States by the end of the year.

Indeed, freight and commuter rail officials speak as if there never was any plan to complete their work on the technology known as positive train control, or PTC, by Dec. 31.

Congress required in 2008 that railroads adopt PTC and gave them seven years to do the job. When it became clear that wasn't enough, Congress gave them another three years. The discussion then was that a few...