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[CNJRoss]

Trains News Wire

 

The quest to counteract ‘loss of shunt:’ Special Report

 

By Bob Johnston | September 5, 2023

 

How a mysterious decades-old problem impacts some Amtrak operations

 

First of two parts

 

EFFINGHAM, Ill, —What happens when electrical current connected with signal systems doesn’t reliably travel from one rail to another when a train passes? Dispatchers “lose” the train — it disappears from their screens — and warning lights don’t flash or gates don’t lower at highway crossings as the train approaches.

 

The phenomenon is called “loss of shunt.” As rail safety issues go, this is one of the most serious anomalies railroads face. What is perplexing is that it may occasionally occur anywhere.

 

SNIP.

 

In mid-August, the latest installment of an ongoing series of tests was staged out of Canadian National’s Effingham yard in southern Illinois. The sessions, attempting to seek a permanent solution for locations where loss-of-shunt issues are ongoing, were attended by participants from CN; Amtrak; the Federal Railroad Administration; the Illinois and California transportation departments, and equipment vendors. More testing is set for September.

 

 

More here.  

[CNJRoss]

Trains News Wire

 

Seeking answers on ‘loss of shunt:’ Special Report

 

By Bob Johnston | September 6, 2023

 

Canadian National takes the lead to fix problem afflicting certain routes

 

Track circuit assistor antennas are mounted over both rails on each truck of a test locomotive to create a circuit for signal detection. Unipart

 

EFFINGHAM, Ill. —The latest round of tests investigating ways to ensure trains always activate track circuits — the process known as “shunt” — involves shunt-enhancing antennas mounted on both trucks of a state-owned locomotive in Amtrak service in California.

 

Here’s how the antennas work on F59PHI locomotive No. 2007: Using electricity supplied by the locomotive in an 11-mile test zone, a specially designed track circuit assistor (TCA) antenna is mounted near each running rail. The TCA antenna induces current into the rails, creating an electrical circuit for signal detection that may not otherwise be reliably transmitted through the train’s wheels. The idea is to create a dependable shunt on the locomotive to obviate the need for axle counts, speed restrictions, or certain types of equipment currently used to address loss-of-shunt issues.

 

Canadian National has been sponsoring the tests over the last several years, with financial and technical assistance from Amtrak, the Federal Railroad Administration, the Illinois and California departments of transportation,and other Class I railroads.

 

In a lengthy statement to Trains News Wire, CN says, “Extensive testing up to this point indicates that the random loss of shunt detection events experienced by single-level passenger equipment in the US is due to the absence of sufficient contact area between the wheels of passenger trains and the rail head. 

 

SNIP 

 

As results of the latest Effingham test are being evaluated, CN says, “Preliminary data collected with both the TCA antenna system active and inactive, conclusively show improvement of the shunting profile with this device. With CN’s leadership, freight rail, passenger rail, lawmakers and regulators are now fully engaged in a conversation about measures to ensure safe signaling by passenger rail.  We are on a path to implement future solutions to ensure enhanced safe operations.”

 

Additional tests are ongoing. Trains News Wire will cover further developments.

 

More here.   

[CNJRoss]

Amtrak is petitioning the FRA for "approval to install on its locomotive fleet, equipment designed to improve shunting of railroad track circuits and reduce the potential for a loss of shunt (LoS) incident (a shunt enhancer antenna).  . . ."

 

Federal Register

 

Petition for Waiver of Compliance

A Notice by the Federal Railroad Administration on 04/19/2024

 

Under part 211 of title 49 Code of Federal Regulations (CFR), this document provides the public notice that on October 17, 2023, Amtrak petitioned the Federal Railroad Administration (FRA) for a waiver of compliance from certain provisions of the Federal railroad safety regulations contained at 49 CFR part 229 (Railroad Locomotive Safety Standards). FRA assigned the petition Docket Number FRA-2023-0095.

 

Amtrak's petition seeks FRA approval to install on its locomotive fleet, equipment designed to improve shunting of railroad track circuits and reduce the potential for a loss of shunt (LoS) incident (a shunt enhancer antenna). LoS within a track circuit causes a signal system or grade crossing system to not detect the presence of a train, significantly increasing the risk of train-to-train collisions and crossing accidents. Known causes of LoS include contaminants on the wheel or rail and locomotive weight, with contributing factors including the number of axles in a train, train speed, wheel profile, and weather. FRA recognizes that a LoS event is a significant safety concern, resulting in both activation failures at equipped highway-rail grade crossings and false proceed signals.

 

Over the last five years, an industry-led working group, the LoS Committee, supported by FRA, has expended significant effort and funding to investigate LoS events, evaluate LoS causes, identify potential solutions, and to test those solutions. The shunt enhancer antenna has been identified, tested, and recommended by the LoS Committee. The LoS Committee confirmed that the shunt enhancer antenna “reliably demonstrate[s] improvement of a vehicle's interaction with the wayside track circuits.”

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