Just days away from a lapse of the current highway program authorizations, Congress is poised to pass another short-term patch before Oct. 29, and farmers and ranchers are urging them to include an extension of the positive train control implementation deadline. Without an extension, railroads are warning a nationwide Class I rail shutdown is very likely.

Positive train control is a GPS-based train control system designed to prevent collisions and over-speed derailments. Under the Rail Safety Improvement Act of 2008, railroads are required to implement PTC systems by the end of this year on mainline tracks that carry "toxic by inhalation" (TIH) materials like anhydrous ammonia-a key fertilizer ingredient-as well as passenger traffic.

Congress plans to continue the highway program authorizations through Nov. 20. Between now and then, lawmakers are optimistic they can finalize a long-term transportation bill.

The Senate this summer passed the Developing a Reliable and Innovative Vision for the Economy (DRIVE) Act (H.R. 22), while the House Transportation and Infrastructure Committee last week approved the Surface Transportation Reauthorization and Reform (STRR) Act of 2015 (H.R. 3763).

Both bills cover six years and include an extension of the PTC implementation deadline beyond Dec. 31, but farmers and ranchers say Congress can't wait until November to act on the issue. BNSF, Union Pacific and other large rail carriers have been working on PTC since the mandate was put in place in 2008, but it's a very large, complex system made up of multiple independent technologies, many of which didn't exist seven years ago.

Without an extension of the positive train control deadline, freight railroads have indicated they will suspend shipments of certain chemicals, such as chlorine used to purify drinking water and anhydrous ammonia used in fertilizer, well before the end of the year.

"A shutdown of rail service is very real, and rail customers are already starting to feel the impacts," the American Farm Bureau Federation and 132 other organizations wrote last week to Congress.

"We have received notifications that disruptions will begin next month to complete shipments that are in transit and that railroads will not accept new shipments. With a shutdown just around the corner, rail customers must start putting contingency plans into motion, including adjusting production schedules and workforce levels."

The House on Tuesday, Oct. 27, will consider a bill (H.R. 3819) to extend surface transportation programs through Nov. 20. The must-pass legislation includes a Farm Bureau-supported three-year extension of the PTC deadline.