From: National Research Council Canada

Good performance and safety of railroads and transit systems requires a harmonious relationship between train wheels and steel rails. Whether carrying freight or passengers, running at high speed or slowly, demands on the wheel/rail interface are tremendous. For example, friction between wheels and rails can fill the air with deafening screeching sounds that upset passengers or communities. Rails can develop cracks or defects that can lead to serious safety concerns, and related maintenance costs could send company budgets off the rails.

The primary method for removing irregularities from worn rails and correcting track issues is rail grinding. Rail grinders are specially equipped trains that perform regularly scheduled maintenance along a system. While rail grinding helps extend the life of a line, at some point aging wheel/rail systems must be updated and replaced.

“Most legacy railway systems do not give sufficient consideration to how the wheels and rails match, so there are usually strong opportunities to improve their performance,” says Eric Magel, Principal Engineer for the NRC’s Resilient Ground Transportation Program. He has proven this in more than 3 dozen wheel/rail optimization projects that span Asia, Australia, the Middle East and South America, among others.

Closer to home, the NRC has been working with ARM to update the technology and services of the San Francisco Bay Area Rapid Transit (BART), a project that started when the district launched its Fleet of the Future Project in 2015. One of North America’s oldest public transit systems, BART is also one of its largest with 131 miles of track and 50 stations, accommodating some 410,000 travellers on an average weekday.

This project is upgrading BART’s revenue service fleet with 775 new cars from Bombardier. With the new cars came a new wheel shape that replaced outdated cylindrical wheels with high-performance, tapered shapes (BT-3) that improve steering, decrease noise and reduce maintenance costs.

Early results showed that reshaping the wheel (and corresponding rail) profiles reduced wheel profile wear by 65% and wheel flange wear by as much as 82%. Wheel/rail-induced noise levels also decreased. “Since we became involved, wheel/rail-generated noise levels have decreased in some locations by as much as 20 decibels,” said ARM President Gordon Bachinsky. The number of noise complaints from riders and residents has dropped, as wellFootnote 1.

“By implementing the NRC’s custom rail templates to match the new fleet and wheel profile, we are anticipating significant extension of life for existing rail on the BART network,” added Bachinsky.

Bachinsky adds that ARM provides not only consulting and engineering expertise in wheel/rail interface, but also contracting and solution-monitoring services. This business model ensures that recommended strategies become reality and that performance is measured. He sees the NRC as an ideal partner for ARM, since the NRC team’s expertise spans all areas that affect wheel/rail interaction: metallurgy, vehicle/track dynamics, contact mechanics and friction managementFootnote 2.

"While we have people at ARM who are quite knowledgeable in this area, the NRC team provides us with critical expertise that guides us in how we carry out the work,” adds Bachinsky. “No one else has the capability to provide us with this kind of know-how.”

An enormous advantage the NRC brings to any such projects is the team’s boots-on-the-ground exposure. Magel points out that they spend considerable time in the field, where they get practical experience on the tracks. “We listen to what Mother Nature tells us, so that helps us go beyond modelling.”

The NRC and ARM will continue their work with BART through a multi-year agreement that includes developing and executing a long-term rail maintenance program. Their key tasks are to provide nightly grind quality assurance/quality control (QA/QC) for the operation of BART’s 2 rail grinders as ARM implements new rail profiles developed by the NRC to match the new wheels. And with scheduled data collection, processing, analysis and presentation, they will track the reduction of rolling fatigue and corrugation.

The bottom line: the NRC-ARM partnership has proven ideal in its ability to provide complementary expertise and services that help ensure that the transition from old to new is done safely, efficiently and cost-effectively.

In 2019, Greg Shivy, BART’s principal track engineer – maintenance and engineering, told Railway Track and Structures (RT&S), a North American rail publication dedicated to covering rail engineering and maintenance of way, that noise complaints dropped by 73 percent in one year after initiating the grinding and wheel reprofiling programs.

Hok Lai, BART principal track engineer - maintenance and engineering, told RT&S in 2021 that “ARM and the NRC’s expertise and services have helped BART effectively manage our rail, reduce railway noise, and make BART a better system for the residents in the Bay Area.”

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