ABSTRACT
I. Introduction ...................................................................................................................... 210
II. History and Statistics ....................................................................................................... 210
III. Railway Vehicle Derailment Mechanisms and Safety Criteria ...................................... 212
A. Flange Climb Derailment......................................................................................... 212
1. Wheel Climb Process ........................................................................................ 212
2. Flange Climb Safety Criteria ............................................................................ 214
a. Nadal Single-Wheel L/V Limit Criterion ................................................... 214
b. Weinstock Criterion .................................................................................... 216
c. Duration Based Criterion ............................................................................ 217
d. AAR Wheel Climb Duration Limit (U.S.) ................................................. 218
e. FRA Wheel Climb Distance Limit (U.S.) .................................................. 218
f. Proposed TTCI Wheel Climb Distance Criterion ...................................... 218
B. Application of Flange Climb Derailment Criteria .................................................. 220
1. Flange Climb due to Low Flange Angle .......................................................... 220
2. Increase of Flange Length Can Increase Flange Climb Distance Limit.......... 221
3. Flange Climb due to High Coefficient of Friction at
Wheel-Rail Interface........................................................................................ 221
4. Flange Climb of Independently Rotating Wheels ............................................ 221
C. Derailments Caused by Gauge Widening and Rail Rollover ................................. 223
1. The AAR Chapter XI Rail Roll Criterion ........................................................ 224
2. The Gauge Widening Criterion......................................................................... 225
3. Effect of Hollow-Worn Wheels on Gauge Widening and
Rail Roll Derailment ......................................................................................... 226
D. Derailment Caused by Track Panel Shift ................................................................ 228
1. Causes of Track Panel Shift.............................................................................. 229
2. Panel Shift Criterion.......................................................................................... 229
E. Derailment Caused by Vehicle Lateral Instability .................................................. 230
IV. Prediction of Derailment.................................................................................................. 231
A. Assessment of Wheel/Rail Parameters .................................................................... 231
B. Dynamic Simulation of Vehicle-Track Interaction ............................................... 232
C. Track Tests ............................................................................................................... 232
V. Prevention of Derailment................................................................................................. 233
A. Wheel/Rail Profiles .................................................................................................. 233
1. Addressing Wheel Flange Angle ...................................................................... 233
2. Removing Hollow-Worn Wheels...................................................................... 233
B. Independently Rotating Wheels............................................................................... 234
C. Installation of Guard Rail or Restraining Rail on Sharp Curves............................ 234
D. Optimising Bogie Suspension and Bogie Yaw Stiffness ........................................ 234
E. Lubrication ............................................................................................................... 235
F. Track Geometry Inspection and Maintenance......................................................... 235
G. System Monitoring................................................................................................... 235
References..................................................................................................................................... 235
Railway vehicle derailment can cause significant casualties and property loss. Avoidance of
derailment is vital to railways for both safety and economic reasons.
