Study of rail breaks : associated risks and maintenance strategies

Railways are large infrastructures and are the prime mode of transportation in many countries. As it is closely associated with passenger and cargo transportation, it owns high risk in terms of human lives and cost of assets. New technologies and better safety standards are constantly introduced but still accidents do occur. There will always be some risk associated with derailments and collisions but it can be reduced by elimination of the root causes. These causes necessitate an effective maintenance strategy to govern optimization of inspection frequency and/or improvement in skill and efficiency. A detailed study of the defects which emerge both on the rolling stock and rail infrastructure is essential to frame out the correct maintenance strategy. Detection and rectification of rail defects are major issues for all rail players around the world. Some of the defects include worn out rails, weld problems, internal defects, corrugations and rolling contact fatigue (RCF) initiated problems such as surface cracks, head checks, squats, spalling and shelling. If undetected and/or untreated these defects can lead to rail breaks and derailments. There are challenges to the infrastructure maintenance people to perform effective inspection and cost effective rectification decisions. If these issues are addressed properly, inspection and rectification decisions can reduce potential risk of rail breaks and derailments. In-spite of continuous efforts made by all rail operators around the world to reduce costs, a substantial amount of railway budget is spent on inspection and maintenance of rails. It is understood that the consequential cost due to derailment reduces with increase in inspection, lubrication and grinding costs. The challenge is to reduce the maintenance cost which consists of inspection, lubrication and grinding costs and at the same time prevent a rise in consequential cost due to derailment. Risk evaluation has become an important parameter for the management to decide a better and cost effective solution that could meet the budgetary constraints regarding renewal, replacement and inspection frequency of rails and wheels. Thus, before development of any model or any empirical relationship associated with risk, familiarity with risk management tools is required. This study focuses on building up a basic knowledge required for establishing such a relationship. The aim is to reduce costs and risks related to rail operation by effective decisions related to rail inspection, grinding, lubrications, rectifications and rail replacements. Different types of rail defects and degradation processes have been studied. From the literature survey and studies done by the author, it is interpreted that there is a need for better prediction of rail defects over a period of time based on operating conditions and maintenance strategies. The issues and challenges related to rail maintenance are outlined for further research in this area. The maintenance strategy followed by Banverket is also described.Godkänd; 2006; 20071210 (ysko)