Rail grinding on Amtrak Northeast Corridor: NRC and Amtrak developed a strategy to get effective grinding done in a minimum amount of time

Railway Track and Structures, June, 2004 by John Pielli, Peter Sroba, Eric Magel

In February and March 2004, Amtrak conducted a high-speed railgrinding operation on its 1,015 miles of track on the Northeast Corridor between Washington, D.C., and Boston. The key objectives of this program were to remove the minor fatigue cracking that typically develops on the high rail between normal grinding cycles and to apply rail profiles that promote improved wheel/rail interaction with the mixed traffic that operates over them.

By regularly maintaining rail through grinding, Amtrak inhibits rail fatigue failure, increases asset life and improves ride quality for passengers.

Poor transverse profiles on the rail will lead to increased wear in curves, hunting in tangent track, and rail surface cracks (Figure 1).

Amtrak grinds the rail to specific profiles designed by the National Research Council of Canada that control wear and simultaneously reduce the wheel and rail contact stresses. In combination with regular rail grinding programs, these profiles increase the life of the rail, increase the life of the wheels on the rolling stock and improve the ride quality of trains and, therefore, increase the comfort level of passengers.

When you reduce the risk of rail surface cracks propagating to severe levels, the safety of trains and passengers improves.

[ILLUSTRATION OMITTED]

Strategy-Northeast Corridor

The Northeast Corridor is a busy section of track with up to 415 trains within a 24-hour period on the Main Spine Outside Terminal Regions, some running at speeds of up to 150 mph. Track time is limited to short windows of three to five hours at night to get most maintenance work completed.

Amtrak followed a best practice guideline to develop and deliver a high-speed and high-production rail-grinding program on the NEC. The National Research Council of Canada was sponsored by the Federal Railroad Administration under a program aimed at understanding and enhancing the performance of the wheel/rail system on Amtrak's NEC.

Amtrak wanted to be absolutely sure that the grinding of a profile onto the rail would not induce poor ride quality for passengers nor require speed restrictions. The proposed profiles must improve the system performance, increase safety and increase the asset life.

Engineered rail profiles

NRC used proprietary software to develop rail profiles to improve the performance of the wheel/rail when matched with the profiles of typical worn Amtrak wheels. These rail profiles were designed to improve wheel life, as well as improve the stability of trains in tangent track and through curves. A family of four rail templates was designed, including two tangent profiles. The "tangent-field" profile was designed to produce a wheel/rail contact biased towards the field side of the rail (Figure 2) while the "tangent-central" produces a central contact band on tangent rail.

In order to allow uniform wear along the entire tread of all wheels and reduce the occurrence of wheel hollowing, each of these profiles was applied to approximately half of all tangent track on the NEC (Figure 3). The field contact profile also helps reduce hunting in long tangent areas where trains travel at high speed (up to 150 mph).

The curve high rails were to be ground to a sharp curve profile (HS) or a mild curve profile (HM) depending on the curvature and the cant deficiency of the track. These profiles were designed to produce more conformal contact with the wheel flange/tread transition to improve truck curving performance and reduce wheel flange wear.

Comprehensive inspection

A comprehensive hi-rail inspection of the track on the NEC was carried out in December 2003 by a team of experts with John Pielli, director track maintenance and compliance, Amtrak; David Rippeth, rail grinding manager, Loram Maintenance of Way, Inc.; and Mike Palloni and Pete Sroba, NRC engineers, present. The profile for each curve and tangent section was evaluated using the NRC Bar Gage with the proposed profile templates and to see if the rail surface had cracks and if trains were hunting in the area.

On this inspection, Loram and NRC developed specific grinding patterns to produce the target profiles in tangent and curves. The patterns needed for Amtrak were different from the ones used on heavy haul to ensure metal was not wasted from the rail. These patterns also allowed most locations to be planned for grinding with a single high-speed pass at 10 mph. Locations where there was rail surface fatigue damage and evidence of hunting were programmed for a slower grinding speed of six mph to remove more damaged material and to produce the desired profile.

[FIGURES 1 & 2 OMITTED]

Grinding plan and implementation

The pre-grind inspection was used to develop a grinding plan. The grinding plan consisted of the following:

-- Each track location feature (i.e., track number, tangent or curve).

-- The degree of curvature.

-- The track length.

-- The grinding pattern for each rail.

-- The grinding speed.

-- The time to complete each segment.

-- The number of shifts to finish each subdivision.