Detection efforts are focused on covering more miles and getting real time results in order to find every defect.

by Mischa Wanek-Libman, managing editor

Sperry

Sperry has made a number of improvements to its vehicles, technology and process during the last 12 months. According to Markus Nottelmann, Sperry's commercial director, the company has made advancements with customers around the world to test at speeds up to 80 kph, approximately 50 mph. The company will be releasing its new 450-series hi-rail vehicles in the second quarter of the year, which have been optimized for transit and yard testing applications. This new vehicle design is fitted with Sperry's 1900 test system, standard ultrasonics, X-Fire RSUs and the latest vision system technology.

Sperry's 950 series rail-flaw detection truck.

The company has developed a new version of its Roller Search Unit, based on the success of the X-Fire RSU, that can be retrofitted to all existing Sperry platforms, including railbound and hi-rail vehicles and walking sticks. 

"Railroads are continually asking to optimize the rail flaw detection process - accomplishing more testing with increased detection and less disruption to railroad operations," said Nottelmann. "We are continually improving the technology to operate more reliably. Our training and quality programs are proving successful in reducing service failures for our customers." 

Nottelmann notes that globally rail-flaw detection is expanding, despite North American railroads adjustments to programs in response to 2009's changed traffic patterns.

Sperry's Integrated Approach, which combines data acquisition, data analysis, reporting and trending to result in an efficient maintenance schedule, is generating interest among North American railroads, where track time has always been at a premium.

"Non-stop testing presents clear operational benefits in reducing track occupancy," said Nottelmann. "To date, four Class 1 railroads in North America have run pilot programs and we continue to refine and expand the program to adapt to each Class 1's specific requirements. The physical layout of the track, traffic and rail conditions are all taken into consideration when deploying the best solution for any individual railroad."

Sperry has also moved into full production of its B-Scan Walking Stick, which provides a complete 10-channel inspection system for pedestrian testing applications. The test system operates to the same calibration standards as Sperry's railbound and hi-rail vehicles and records GPS location data to supplement milepost and landmark features. The test data is compatible with other existing Sperry inspection systems and can be transmitted directly from the walking stick via built-in GSM/GPRS cell phone data service.

"The greatest benefit of this new test system is the complete auditable record of test in pedestrian testing applications, which satisfies the FRA reporting requirements of the railroads," said Nottelmann. "The B-Scan walking stick is available in three variations: a single-rail walking stick, a dual-rail system and a trolley traveling at up to 10 mph to test any rail, anywhere with optimum efficiency."

Limited track time isn't the biggest challenge facing rail-flaw detection programs. Nottelmann points to the unpredictability of the condition of the rail as the biggest challenge.

"Non-Destructive Testing solutions in other industries have the luxury of preparing the surface of the test piece before inspection. The railroad is a harsh environment and the railroads expect a reliable test at high speeds, regardless of rail condition," said Nottelmann. "The way the Sperry RSU adapts to changing surface conditions and rail wear has always been an advantage. Now, Sperry is leading the way in the real-time analysis of the combined technologies of ultrasonic, induction and eddy-current systems, which can look through and under fatigued and worn rail surfaces to find defects that were previously masked."

Nottelmann continued, "Another big challenge, as it is with many business processes, is to continually automate the rail-flaw detection process to minimize the need for operator interpretation. Sperry has a focused three-phased approach to meeting this challenge: a) ongoing continuous improvement of processes and training applied to the existing fleet; b) implementing new hardware and software solutions that handle a greater percentage of the decision-making process and c) streamlining the rail-flaw detection process through the introduction on non-stop testing in the North American market.

"What railroads want today is reliability. We continue to invest in technology, systems, processes, training and people to ensure that at each level of the rail flaw detection process there is built-in redundancy and intelligence to monitor performance and detect faults, even before they occur.

"We continue to expand our training program to ensure that our operators have all the tools to do the best possible job, day after day. Our operator training and certification standards far exceed industry standards and FRA requirements, and we continually improve the program through recertification and effective audit processes that measure quality and reliability," said Nottelmann.

Herzog

Herzog Services Inc. has developed several new products for the rail-flaw detection market including a joint bar inspection vehicle, base corrosion index and push carts.

Herzog has been working with TTCI to develop a working-prototype ultrasonic joint bar inspection vehicle based on a TTCI study that found 95 percent of broken bars originate from a crack that is centrally located at the top of the bar, which propagates into a failure at the joint if not caught in time.

"We have developed a RSU and software package that will scan the bars for cracks that might not be detected using the standard visual methods," said Troy Elbert, project manager at Herzog. "The first prototype was displayed at TTCI and also has been demonstrated on a Class 1 railroad in the last quarter of 2009. Both demonstrations were successful in proving that detection of ‘hidden' cracks, such as those concealed by the head of the rail during visual inspection, is possible using a UT method mounted on a hi-rail vehicle. Version II corrects/improves some of the mechanical difficulties Version I uncovered and Version II is scheduled to be released in March."

Also in development at Herzog is a Corrosion Index Map. According to Elbert, several railroads have approached the company to develop a method of detecting the amount of corrosion on the bottom side of the rail base.

"It is thought that if when the corrosion reaches a certain ‘depth,' it will cause a stress riser and result in a broken rail. At this moment, we have collected a fair amount of data in order to develop a Corrosion Index Map. We are hoping, with continued efforts from several roads, we can bring this product to market as a useful tool in monitoring areas that are prone to failure due to this anomaly," said Elbert.

Herzog also continues to develop a smaller, lighter and what it calls more capable push cart for inventory rail and crossovers. The company has released a prototype cart for evaluation that includes recordable BScan with milepost entry and GPS.

Herzog is also in the first stage of developing a more interactive GPS-based data review program. Currently, it will provide a "bread crumb trail" of the test data, which can be overlaid on maps, such as Google Earth, that shows the satellite imagery, as well. 

"The bread crumb trail also shows markers and icons for various structures and testing information. This allows us to double-check the accuracy of our DGPS system and operator inputs. The next step will incorporate automated auditing by comparing features in the current test data with those that match up, both by GPS and test features. This will allow our auditing team to scan more tapes easily and effectively," said Elbert.

According to Elbert, railroads have been asking for maximized efficiency with each work window, which means incorporating more services into Herzog's program.

"For instance, it would maximize the effectiveness if we were able to include/add track geometry into our Ultrasonic Testing program. This could provide useful information regarding the track conditions and, along with UT information, could provide more concise data for rail defect trending," said Elbert.

"Track time is and will always be a factor. One solution that we are pursuing this year is to develop a system for high-speed non-stop testing. The theory is to  collect ultrasonic data over a section of track in a continuous mode. All defect identification and verification would be done post-scan and referenced to any precluding tests that we may have performed on the track segment. This allows the test vehicle to move uninterrupted within the available work window to gain as many track miles as possible. This is not a novel idea. However, we feel that with the right approach and management, it could be a successful adventure," said Elbert.

Dapco

Dapco Industries, Inc., added two new products to its line up including a digital signal processing electronics package and a newly redesigned detector car that integrated additional inspection technologies.

Dapco partnered with Texas Instruments and used the latest in DSP technology to develop a new digital signal processing system.

"We are implementing a new system architecture, which represents the next generation of test and inspection instrumentation," said Bob Coakley, marketing and sales manager at Dapco. "The new system architecture will significantly increase our precision and, because of the capabilities of the TI DSP, we will be able to examine defect/signal characteristics much more closely than we could in the past. Moreover, the system will have the intelligence to dynamically and automatically categorize defects, reducing the risk of human operator error."

Coakley notes that while the company continues to work on the railroads' needs relative to enhanced defect detection, a focus has been placed on integrating parallel technology on a detector car.

"Given that a stretch of mainline track is often ultrasonically inspected every 21-30 days via a detector car, we are seeing a new trend where the railroads are now asking for other technologies to be installed onboard detector cars," said Coakley.

In response to this new trend, Dapco has introduced a newly redesigned detector car that has integrated ultrasonic RFD, line scan imaging and rail profile measurement technologies.

"This is the first time that rail profile measurement has been included onboard a detector car, providing clients with the ability to overlay ultrasonic data along with images of the rail, gauge measurement information and rail profile information," said Coakley. "This will offer the railroads a powerful tool in being able to better understand the current condition of their rail infrastructure. When reviewing a section of track - post test, it will offer additional vital information about the condition of the rail surface, rail wear and rail gauge at the time the test was conducted."

He also points out the challenge of keeping up with the ever-changing rail/track conditions and making sure rail-flaw detection technologies change, as well.

"For example, recently several Class 1 railroads implemented new style frogs that have higher guards than have been used in the past. The challenge is that the tradition RFD detector car was not able to test through these new style frogs. This created a situation where the track adjacent to the frog was being classified as a ‘no test area' and the railroad was required to send a second crew back to this location to inspect the rail for defects using manual/portable RFD instruments.

"To eliminate the problem created by the new style frogs, Dapco redesigned its rolling search unit and improved the clearance to allow the detector car to be able to complete the inspection of the adjacent track," said Coakley.

Rail-flaw detection and rail stress monitors

 by Ryan S. McWilliams, Portec Rail Products, Inc.

An optimum rail integrity program requires a proper rail-flaw inspection scenario, the identification and removal/repair of defective wheels and maintaining longitudinal rail forces to safe levels such that the operating risks are minimized.

When one goes back to first principles, we analyze the problem as follows: Rail breaks occur from just two primary conditions converging at the same point. A rail must have some sort of internal or external flaw. Said rail must have an external event disturb it’s geometry, such as wheel impact and/or rail stress.

The simple fact is that most rail flaws would not cause the rail to break if it were not for external forces being imparted into the rail. These forces can come in two primary forms. Wheel impacts are the most obvious of these damaging forces. The second is the longitudinal stress caused by thermal changes in the rail (heat expansion and cold contraction) and by geometric changes such as those caused by rail running down hill, general track maintenance and by curves “breathing” in and out as temperature heats and cools the rail. This rail stress condition is almost never known and even less often monitored.

If these two external forces occur simultaneously as they commonly do, then it provides for a complex probability of determining if a rail will break. This is why there are AAR rules that state a wheel impact of 90,000 pounds is condemnable and the location specific railroad guidelines stating rail neutral temperature (RNT or rail laying temperature) should be approximately 100-degrees Fahrenheit.

The Class 1’s in North America have done a great job in deploying WILD (Wheel Impact Load Detector) systems throughout their network over the past two decades. We are now coming to a time when rail stress monitoring (RSM) is emerging on the horizon. These RSM systems allow the railroads of today to maintain a balancing act between incurring track panel buckling on hot days and rail pull-aparts on cold nights by installing rail at the proper temperature. Due to the rail changing its stress condition on a minute-by-minute basis, we need to continuously monitor this rail stress situation. If we never had a temperature change or, if we never had a train run over the system, then we would be in pretty good shape when it comes to rail stress.

Let’s not forget that all problems have more than one variable and most problems on the railroad have more unknown variables than they have known. If we don’t know the current Rail Neutral Temperature or the size of the rail flaw, then we are simply shooting in the dark and gambling with our own safety. Using technologies such as Ultrasonic’s, WILD’s and RSM’s may only be part of the solution, but they are a great start.