Preventing Derailments atonlinepubs.trb.org/onlinepubs/trnews/rpo/rpo.trn191.pdf · relatively high...
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T RESEARCH PAYS OFF Preventing Derailments at ALLAN M. ZAREMBSKI urnouts, where rail vehicles are physically moved from one track to another, and other special-trackwork areas are geometrically complex and pose a relatively high risk of train derailment. At these locations, the direction of a train's momentum differs from the direction of the track. The high forces created between the vehicle's wheels and the track can lead to derailments. Factors re- lated to switch geometry, track maintenance, vehicle characteristics, and operating condi- tions can increase these forces. PROBLEM From 1984 to 1996, approximately 200 derail- ments occurred at turnouts and other special- trackwork areas of rail-transit systems in the United States. These derailments can have seri- ous consequences. The derailment on the Bay Area Rapid Transit system that occurred on a main-line interlocking in December 1992 re- sulted in injuries to riders and substantial track damage. About $2.2 million was expended to repair track and rolling-stock damage. Fortu- nately, most derailments occur in yards and not on main tracks, where the consequences could be catastrophic. Nevertheless, derailments, wherever they occur, are costly and can result in serious injuries to transit patrons and employees. SOLUTION Under the Transit Cooperative Research Program, sponsored by the Federal Transit Administration and administered by the Transportation Research Board, a study was conducted to identify techniques that can be used to effectively reduce the potential for derailments on special trackwork. Objec- tives of this study were to determine the loca- tion, frequency, and mechanisms of such de- railments; to evaluate, through both field test- ing and computer model simulation, devices currently in use to reduce the risk of derail- ments; to identify the inspection and mainte- nance practices now in use; and to recommend new and modified derailment-mitigation tech- niques. To better understand derailment mechanisms, several types of turnouts on two transit systems were instrumented and monitored under a range of operating conditions. The measurements ob- tained from the tracks and from vehicles trav- ersing them were correlated. A variety of de- vices and maintenance practices intended to reduce derailment risk were examined at the test locations, and their effectiveness in reducing the levels of detrimental forces was measured. A computer-simulation model was used to deter- mine the potential effectiveness of proposed mitigation devices that had not yet been manu- factured and thus could not be physically tested. The model was calibrated using data obtained from the two field studies. The adoption of comprehensive maintenance and inspection standards were found to be highly effective means for reducing derailment potential. Rail lubrication and the use of sev- eral devices, such as extended guard rails and switch-point protectors, were also found to be highly effective. Other findings are noted in the report on Project D-2, "Derailment of Transit Vehicles in Special Trackwork," which is available through the Transit Coop- erative Research Program, Transportation TR NEWS 191 JULY–AUGUST 1997 20
Transcript of Preventing Derailments atonlinepubs.trb.org/onlinepubs/trnews/rpo/rpo.trn191.pdf · relatively high...
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RESEARCH PAYS OFF
Preventing Derailments atALLAN M. ZAREMBSKI
urnouts, where rail vehicles arephysically moved from one track toanother, and other special-trackwork
areas are geometrically complex and pose arelatively high risk of train derailment. At theselocations, the direction of a train's momentumdiffers from the direction of the track. The highforces created between the vehicle's wheels andthe track can lead to derailments. Factors re-lated to switch geometry, track maintenance,vehicle characteristics, and operating condi-tions can increase these forces.
PROBLEM
From 1984 to 1996, approximately 200 derail-ments occurred at turnouts and other special-trackwork areas of rail-transit systems in theUnited States. These derailments can have seri-ous consequences. The derailment on the BayArea Rapid Transit system that occurred on amain-line interlocking in December 1992 re-sulted in injuries to riders and substantial trackdamage. About $2.2 million was expended torepair track and rolling-stock damage. Fortu-nately, most derailments occur in yards and noton main tracks, where the consequences couldbe catastrophic. Nevertheless, derailments,wherever they occur, are costly and can result inserious injuries to transit patrons and employees.
SOLUTION
Under the Transit Cooperative ResearchProgram, sponsored by the Federal TransitAdministration and administered by theTransportation Research Board, a study wasconducted to identify techniques that
can be used to effectively reduce the potentialfor derailments on special trackwork. Objec-tives of this study were to determine the loca-tion, frequency, and mechanisms of such de-railments; to evaluate, through both field test-ing and computer model simulation, devicescurrently in use to reduce the risk of derail-ments; to identify the inspection and mainte-nance practices now in use; and to recommendnew and modified derailment-mitigation tech-niques.
To better understand derailment mechanisms,several types of turnouts on two transit systemswere instrumented and monitored under a rangeof operating conditions. The measurements ob-tained from the tracks and from vehicles trav-ersing them were correlated. A variety of de-vices and maintenance practices intended toreduce derailment risk were examined at the testlocations, and their effectiveness in reducing thelevels of detrimental forces was measured. Acomputer-simulation model was used to deter-mine the potential effectiveness of proposedmitigation devices that had not yet been manu-factured and thus could not be physically tested.The model was calibrated using data obtainedfrom the two field studies.
The adoption of comprehensive maintenanceand inspection standards were found to behighly effective means for reducing derailmentpotential. Rail lubrication and the use of sev-eral devices, such as extended guard rails andswitch-point protectors, were also found to behighly effective. Other findings are noted inthe report on Project D-2, "Derailment ofTransit Vehicles in Special Trackwork,"which is available through the Transit Coop-erative Research Program, Transportation
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Research Board, 2101 Constitution Avenue,N.W., Washington, D.C. 20418. Some of thesefindings are relevant to efforts to reduce therisk of derailments on railroads.
BENEFITS
Use of the recommended devices and procedureswould greatly reduce the incidence of derail-ments both on main lines and in yards, increas-ing the safety of passengers and workers. In ad-dition, economic benefits would accrue throughthe decrease in maintenance costs and downtimeand the increase in the service life of trackworkcomponents. A significant cost savings would berealized through avoidance of a derailment at aturnout, which can result in repair costs of sev-eral hundreds of thousands of dollars.
For further information, contact Dr. A.M.Zarembski, ZETA-TECH Associates, Inc., 900Kings Highway North, Suite 208, Cherry Hill,New Jersey 08034 (telephone 609-779-7795; e-mail [email protected]).
EDITOR'S NOTE: Special appreciation is ex-pressed to Amir N. Hanna and G. P. Jayapra-kash, Transportation Research Board, for theirefforts in developing this article.
Suggestions for "Research Pays Off" topicsare welcome. Contact G. P. Jayaprakash,Transportation Research Board, 2101 Con-stitution Avenue, N.W., Washington, D.C.20418 (telephone 202-334-2952; [email protected].).
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