A closer look at rail flaws: all rail develops metallurgical flaws sooner or later. Sophisticated technology is enabling railroads to locate and remove these flaws before they become a problem

Railway Track and Structures, Annual, 2008

A good rail-flaw detection program usually consists of effective equipment, proven technology and well-trained operators working in harmony. Here's a look at what companies are doing to find flaws before a train does.

[ILLUSTRATION OMITTED]

ENSCO

As a result of a joint development program with the Federal Railroad Administration's Office of Research and Development, ENSCO, Inc., has developed the Joint Bar Inspection System to address industry challenges and needs related to rail-flaw detection. ENSCO says the system is expected to reduce the need for visual or manual joint inspections, as well as provide early detection of cracked joint bars and missing fasteners. JBIS can be applied as an enhancement to existing rail-flaw detection programs, has been installed on hi-rail and inspection car platforms and can operate at more than 50 mph.

According to ENSCO, the system automatically detects the joint bar, takes a high-resolution image and then utilizes advanced image processing techniques to locate cracks and highlight them for inspectors to evaluate.

"Through automatic capture of joint bar images from a moving platform, the system eliminates the need to walk the track and inspect each joint manually. Automated image processing allows users to flag and review high-risk joint bars in the field or office. Current data processing statistics show that 200 miles of cwr can be reviewed in approximately two hours from an office workstation post data collection. In addition, the system produces automated GPS-located joint inventory/joint per mile reports for maintenance-of-way planning, a secondary need that has been identified throughout the industry," said Jeff Stevens, manager of business development, rail technology division, ENSCO.

According to Stevens, the biggest challenge faced by JBIS has been related to reduction of false crack detections by the automated processing algorithm.

"Based on recent test analysis, we have determined the false detection factors that can be reduced or eliminated by the crack detection algorithm include: grease spots, rail gaps, watermarks and rust. Factors that will continue to produce false detection unless addressed by railroad maintenance include frayed bond wires, weeds and grass. Regardless of false detections, the system continues to provide a highly-effective approach for inspecting joint bars at a fraction of the time required by traditional track walking. Combining this technology with other inspection systems such as ENS-CO's V/TI system, which detects locations where joints are experiencing potentially damaging impact loads from traffic, offers additional capacity for significantly reducing the risk of joint failure," said Stevens.

Herzog

"As with most rail-related businesses, Herzog experienced growth in 2006 as well," said Troy Elbert, project manager at Herzog Services Inc. "With our customer base expanding and demand on the upswing with existing customers, we fully expected to see continuing growth throughout 2007."

[ILLUSTRATION OMITTED]

Projects in 2007 included the development of a new database to fully utilize Herzog's DGPS-equipped test systems. According to Elbert, this new Web-based database will integrate a variety of information and will host customer portals for access to client-specific information.

"We continue to improve our test system with new hardware and software to take advantage of the latest technologies. Faster processors and more powerful microprocessors will allow us to do more signal processing and more adaptive recognition software," said Elbert. "In the midst of building new test vehicles, we also have managed to continue new ideas with our transducer array. Most of the successes have come in the form of new materials for cost and weight reduction, and we will continue to press on with new ideas and angles to continue to provide quality products to our customers."

"We were also invited to help with a project in Pueblo, Colo., at the TTCI facility in December 2006. This project focused on emerging technology in non-contact ultrasonic testing. This method, if proven, could lead to faster test speeds by eliminating the mechanical and physical constraints of current Roller Search Unit (RSU) arrays. For instance, we have found the physical properties of the fluid inside the RSU can be a limiting factor on the speed at which conventional RSU-based testing can be performed. At excess speeds, much higher than our standard operating speeds, the centrifugal force of the water distorts the current membrane, or 'tire' to the point of premature failure of the sidewall. We will continue with TTCI on this project to reach a viable solution to the problem of less available track time, which seems to be ever increasing as the rail industry expands to meet the increasing appetite for energy and goods of the American populous," said Elbert.

SPENO INTERNATIONAL

SPENO INTERNATIONAL SA has developed a multi-element phased array unit and a patented carrier trolley. In order to protect the unit from mechanical shocks, the company has also developed a belt system using high-speed sliding probes without having direct contact with the rail, which allows testing on bad track conditions without any risk of damaging the probes. SPENO points out the main advantage of multi-element phased array technology is the flexibility of inspection, while the carrier trolley allows testing at higher speeds and ensures constant contact for ultrasonic testing.