Following a number of main-line derailments involving rail rollover in curves, Norfolk Southern(NS), working with Transportation Technology Center, Inc.(TTCI), established a rail test site in a 7.8-degree curve on a heavy-tonnage coal route to investigate the relationship among wheel/rail forces, track conditions and dynamic rail cant. Wheel force measurements were collected over a 15-month period during 2011 and 2012 under a variety of track maintenance conditions, including tight, standard and wide gage; cut spike and elastic fastening systems; three rail grinding cycles; with and without top-of-rail friction modifier(TOR); and at two different super-elevations. The following conclusions were made based on the lateral-force data associated with each of the track conditions: 1. Very high lateral forces and significant rail cant(close to roll-over)can result from adverse wheel/rail contact. 2. Track maintenance tasks that involve changing gage or rail orientation can have the unintended consequence of causing adverse wheel/rail contact, resulting in high lateral forces. 3. Managing the wheel/rail interface by modifying track gage, rail profiles, elevation, fastening systems and TOR friction control can lower lateral forces. 4. Cut spikes do not provide sufficient vertical rail restraint when subjected to high lateral forces. 5. Elastic fasteners appear capable of handling high lateral forces.
展开▼
