Brad Kerchof
Norfolk Southern Railway
Abstract:
Correcting Adverse High Rail Profiles to Promote Desirable Wheel Contact and Rail Stability
A half-dozen curves on NS’s Pittsburgh Line west of Altoona had open gage (57-1/4”) and high rails with 3° of outward cant due to severe tie plate cutting. Because of these high rails had existed in this orientation for several years, their profiles had developed a wheel-conformal shape, through wear and grinding, at that canted-out position. Preparation for programmed tie and surface job involved correcting the open gage and removing the cant, improvements that are best accomplished by gaging the high rail. The high rails presented a significant risk to track stability, however, if they were to be set upright with their existing profiles.
NS has experienced a number of rail roll-over derailments that have these characteristics in common:
- The high rail had been allowed to exist for some time in a canted-out position, which resulted in the rail taking on a profile with a gage corner that was lower, and a field side that was higher, than an uncanted rail.
- Track maintenance was performed – either gaging or tie installation – that resulted in the high rail’s orientation being changed from, say, 3° outward to 0° (0° is equivalent to the position established by 1:40 tie plates on good ties).
Correcting the cant resulted in wheel tread contact on the field side, a condition known as severe two-point contact, which is very poor for axle steering and can create very high lateral forces, high enough to induce rail roll. Following these derailments, NS established a policy of not gaging high rails that have this kind of worn profile outward unless the profile is corrected.
This presentation describes the planning and execution of the grinding of these six high rails to achieve a profile that would allow for desirable wheel contact after the rails were set upright, as well as the results that were achieved.