A U.S. watchdog office urged Congress to empower regulators to extend a Dec. 31 deadline for freight and passenger railroads to adopt new safety technology that could prevent major derailments and other deadly crashes.

A new report from the nonpartisan Government Accountability Office found about two-thirds of railroads, including the largest freight carriers, will need another one to five years to implement the technology known as positive train control, or PTC. Safety experts say it would have prevented a May 12 Amtrak derailment that killed eight and injured more than 200 others.

The report surfaced a week after major freight railroads stepped up pressure on Congress to extend the deadline by warning of crippling disruptions to the national rail system if the Dec. 31 target date remains in place.

Lawmakers have not settled on what kind of extension to grant or on how to write prospective legislation.

The report said Federal Railroad Administration efforts to oversee PTC implementation have not been “sufficient to monitor and report on the progress of individual railroads,” partly because rail operators did not update the agency on plans.

Railroad officials have complained about the cost and complexity of adopting PTC.

The FRA was also slow to act, not forming a PTC taskforce until only seven months before the year-end deadline, the report said.

“Providing FRA with the authority to grant extensions on a case-by-case basis would provide some needed flexibility and could also assist FRA in managing its limited staff resources,” GAO told the lawmakers.

A six-year transportation bill approved by the Senate last month would allow the Obama administration to extend the deadline for up to three years. But it was unclear if the Senate measure would be taken up by the House of Representatives.

In 2008, Congress mandated that railroads implement the technology by the end of 2015. But only a small number of U.S. passenger, commuter and freight railroads will meet the deadline, according to an Obama administration report released last month.