Thursday, February 06, 2014

What's the diagnosis?

Written by  Mischa Wanek-Libman, Engineering Editor

High-tech track inspection gives railroads a clear picture of their maintenance needs.

Automated track measurements assess overall track structure and individual components and, over time, can illustrate infrastructure health trends to aid in maintenance planning. Companies that provide track assessments run into shared challenges, but each works to find solutions through research and working closely with customers to develop a clear understanding of a railroad's needs.

Assessment challenges

By far, the most pressing challenge faced during track measurement is adequate work windows.

Larry Mahon, area operations manager for Balfour Beatty Rail, a division of Balfour Beatty Infrastructure, Inc., which is responsible for maintenance on the trio of main lines that make up the Alameda Corridor, says, "On some days, the heavy volume of traffic makes thorough and complete inspections more difficult than usual. Because of FRA regulations, we can't inspect all three tracks at once unless there's

a second qualified inspector in the vehicle and the track centers are no more than 39 feet apart. On the Alameda Corridor, the track centers are 15 feet apart, but there are 143 power switches and each has to be inspected monthly. With traffic the way it is, it's a challenge making thorough track inspections and walking to each switch."

Eric Sherrock, senior staff engineer at ENSCO, Inc., explains, "With high traffic volumes on freight lines and the growth of passenger services around the country, as well as ever increasing demands placed on railroad workforces, the time available for the range of various inspections required is becoming more difficult to schedule."

Sherrock also notes that with regards to track components, the identification of rail breaks, which continue to be identified as a leading cause of track-related derailments, prior to a derailment is of critical importance to the industry, especially with the impending implementation of positive train control and the eventual decrease in reliance on track circuits.

ENSCO sees railroads trending toward comprehensive track inspection in a single pass from vehicles equipped with several complimentary inspection systems, such as the full-sized self-propelled inspection vehicle the company delivered to WMATA in 2012 that is capable of simultaneously measuring track geometry, rail profile, platform edges as well as third rail geometry and temperature. The vehicle is also

able to record video and thermal images of the tunnels and conduct ultrasonic rail-flaw inspections, all while capturing foot-by-foot track measurements in a single pass.

Joe Palese, senior director, engineering & technology at Harsco Rail, which provides the Automated Switch Inspection Vehicle, also sees a need for more comprehensive inspection technologies to take full advantage of track time.

"With track time being limited, most customers require inspection to occur at track speeds. Customers want inspection at track speed and for it to be autonomous as opposed to dedicated inspection," he says. "Harsco Rail has been investigating and developing technologies that can be deployed on hi-rail vehicles for easy on/off to take advantage of short work windows. In addition, Harsco Rail has been investigating deploying these systems on other work equipment (grinders, tampers and UTVs) to take advantage of the allocated work window."

Nordco, Inc., has incorporated track permit validation into its testing software of its skid-mounted and vehicle-mounted Flex Inspection System. The permit validation allows for proper work window management and adds an extra layer of safety for the inspector.

"Our testing software now includes a track permit validation enhancement," says Bob Coakley, director of sales and marketing at Nordco. "When the operator receives the track time information from the railroad, either/both the mile poles or times are entered in the system. Shortly before the track permit parameters are met, e.g., 10 minutes before time expiration, the operator receives a warning message. This allows the operator to either quickly exit the track or call for a track permit extension. The testing software automatically shuts down if the operator does not respond to the warning message."

Holland LP says a challenge in track measurement is the validation of rail cant measured by track geometry test vehicles. Holland's TrackSTARĀ® fleet measures rail cant along with track geometry on one foot increments. Bob Madderom, vice president and general manager with Holland LP, says it has become standard practice for railroads to measure and report on rail cant exceptions from automated track geometry cars.

"Essentially, we now have the capability to identify rail cant exceptions in the normal course of our reporting for all measured track," says Madderom. "Rail cant measurement has become a very important measurement of condition of track. Differential plate cutting on wood ties in heavy tonnage or poorly maintained track can be a problem. Also, rail cant variation on concrete ties is an effective way to identify potential areas of worn pads, or worse, rail seat deterioration (RSD).

In addition to utilizing rail cant to identify potential tie problems, systems such as Georgetown Rail Equipment's (GREX) Aurora Automated Tie Inspection system can be used to measure tie surface characteristics, such as plate cutting, to accurately report tie condition.

GREX's Aurora system uses high-speed cameras and lasers to provide a tie condition assessment and report, which can be customized to meet specific customer needs.

"GREX develops exclusive tie grading models for each customer using sophisticated algorithms that embed unique grading characteristics specific to that customer. These unique characteristics are identified during a walking calibration process with the human tie inspector. Aurora then 'learns' these grading attributes and begins to mimic the expert inspector, mirroring the grading results," says Lynn Turner, vice president marketing and sales for GREX. "This output, in a 3-D digital track image along with the statistical analysis of tie condition, allows a critical and thorough reporting and assigns each tie an exact GPS location signature.

Incorporating rolling 39-foot defects, joint tie defects, and clusters of failed ties into customized reports are typical of customer-presented challenges that GREX engineers have developed solutions for. It is no coincidence that customers who have invested the most effort into Aurora have realized the best performance."

Advantages of automated measurements

"One of the most significant advantages of autonomous inspection technology is that every movement of the host train offers an opportunity to evaluate the track, allowing for more frequent inspections without track time being consumed by dedicated inspection vehicles. The use of autonomous inspection technologies can result in earlier detection of track defects, allowing for maintenance practices to be preventative rather than reactive, ultimately reducing the number of track related derailments," says ENSCO's Sherrock.

Plasser American defines the track network as a dynamic system under constant change from varying factors such as rail traffic, the nature of the subsoil, temperature fluctuations or precipitation. To plan maintenance work efficiently, it is necessary to know the current state of the track and, above all, recognize possible deteriorations.

Plasser, which offers a range of track measuring machines, recommends regular measurements carried out by multi-function track recording cars several times a year to obtain the relevant data, which includes at least track geometry, rail profile and rail surface, complemented by driver's view and track component video images.

Plasser's multi-function track recording cars integrate various measuring and video systems, which in combination, as used on MTA's Track System in New York City, allow for comprehensive analysis of the track and the track structures. Collecting as much data as possible in one run reduces track occupation time and provides tremendous operational and economical advantages. Video systems installed on a multi-function track recording car support and reduce track walking inspections.

Plasser's high-speed, high-tech multi-function track recording cars have provided railroads worldwide with accurate track data for many decades. The data recorded by the multi-function track recording cars can be directly input into the guidance systems of Plasser's tamping machines, increasing track quality and productivity.

The company says the recorded data, merged into a railroads track and asset database provides the means for long-term analyses, providing planning offices a valuable instrument. Rates of deterioration, derived from exception reports and track quality indices indicate which type of action would be the most suitable and economical solution to restore the target geometry of the track and to retain it as long as possible.

Robert Grant, director of engineering sales for NxGen Rail Services, a Sasser Family Holdings Co., believes that condition-based maintenance of track and rolling stock will provide significant savings, as well as improvements in safety as railroad maintenance activities continue to become proactive. NxGen Rail Services says it provides maintenance planners with a "holistic view of their asset" by using machine intelligence to report precise locations of defects, enabling planners to examine them from different points of view to better understand the causes of the problems and design better solutions.

"Technology has evolved and the benefits of incorporating automation through machine vision into inspection processes are well documented and proven," says Tom Keogh, president of Rail Radar. "Rail Radar's 3-D system uses industry proven machine vision techniques to improve the efficiency, effectiveness and objectivity of the track inspection process [and] capitalizes proven technology through data acquisition, through image analysis and through data analysis, with input from the railroad's maintenance and track experts."

Harsco's Palese says the data gathered during the inspection of any component can also be turned into a wealth of information for understanding component degradation and failure.

"This allows for developing maintenance practices to pro-long the life of the components. Addressing the most critical components first is of paramount importance," says Palese.

Balfour Beatty's Mahon believes that despite advances in automated technology, eagle-eyed inspectors still have their place in the process. "There's no substitute for good visual track inspections," he says. "Geometry cars will find things the eye may miss, but they can't find things that a walking person will. It all comes down to working with the dispatching center to make sure everyone understands the requirements so the FRA regulations are met."