Railroads will get three more years to implement positive train control (PTC) following the passage of a transportation bill in the House and Senate this week.

On Tuesday the House passed short-term legislation for a transportation measure that includes extending the deadline for PTC, a safety requirement designed to prevent train collisions, to Dec. 31, 2018. A day later, the Senate approved the measure, HR 3819, which now goes to the White House for sign-off.

The extra time comes through a measure that extends for three weeks the operation of public transit and highway programs while Congress continues work on a long-term authorization bill.

Transportation leaders lobbied for an extension of this year’s Dec. 31 PTC deadline that requires railroads to install the safety system across portions of freight and passenger systems. In August the Federal Railroad Administration reported that most railroads would not be compliant by the deadline. Railroads, which could face civil and criminal penalties by continuing to operate if not PTC compliant, said they would suspend service if the deadline was not extended.

The Association of American Railroads (AAR) said the industry has made “substantial” progress in implementing PTC but holding the 2015 deadline would be “devastating” and lead to halting freight rail transportation and significant economic pain. AAR said halting rail service could cost the U.S. economy $30 billion and force 700,000 out of work.

PTC is required to be implemented on Class I railroad main lines over which any poisonous- or toxic-by-inhalation hazardous materials are transported, and on any railroad’s main lines over which regularly scheduled passenger intercity or commuter operations are conducted.

Railroads have invested significantly to comply with what has been an evolving safety measure. The Rail Safety Improvement Act of 2008 mandated that PTC be implemented across a significant portion of the rail industry, but the final rule addressing requirement wasn’t approved until two years later.

Freight railroads have spent close to $6 billion on PTC development, testing and installation, the AAR says. An estimated $4 billion more will need to be spent before the technology is fully operational across the United States.

AAR President and CEO Edward R. Hamberger lauded the bipartisan votes by lawmakers in the House and Senate to pass HR 3819 and extend the deadline.

“This provides the certainty American industries and businesses need to serve the millions of Americans who rely on rail every day,” he said. “The extension means freight and passenger railroads can continue moving forward with the ongoing development, installation, real-world testing and validation of this complex technology.”

Michael Melaniphy, president and CEO of the American Public Transportation Association, said the extension avoids a situation that could have put more cars on the road if passenger rail systems were shut down.

“By implementing a realistic timeline for PTC, the disruption of Americans who take nearly 2 million daily trips on commuter rail systems every weekday was avoided,” he said in a statement. “This extension prevents the shifting of these daily commuter rail trips onto overburdened roads, which could have contributed to an unsafe commuting environment.”