SAFETY STANDARDS FOR TRANSPORT SYSTEM DEVELOPMENT- COMPARISON, EFFORT AND CHALLENGES

摘要

The technical and economical relevance of safety and reliability in transportation systems - in all branches of transport - has long been increasing. This has partly been a result of the increasing number of systems responsible to the assurance of safety in modern vehicles. According to current standards, a risk analysis must be conducted for every new transportation system before its employment can commence. The goal of this analysis is to identify and quantify all possible risks, or events that could potentially lead to dangerous situations, as related to the operation of the system. Hence, the degree of fulfillment of these safety standards must be properly documented and kept as a proof of safety for the system. This article compares the norms, standards and guidelines of various certification methods for manufactures and operators for air, rail and road transportation, and reveals existing weak points in their usability.The most important norm in the extensive landscape of standards is surely still the IEC 61508. This very generally formulated norm describes the requirements that electrical, electronic and programmable systems related to the safety of a transportation system are needed to meet. Among the operations under the umbrella of this norm are today's transportation systems and their subsystems (i.e. driver assistance systems, etc.).A comparison of the dominant transportation modes - roads, rails and air - clearly demonstrates that the degree of fulfillment of several parts of the standard depend heavily upon the varying intrinsic properties of the mode of transportation and thus should be viewed accordingly. Differing modes of transportation may therefore require more detailed, branch-specific norms in order to be properly assessed for certification.In light of this, various committees from the automotive and railroad industries are at work adopting the IEC 61508 in order to regulate the certification process as concerning safety and risk analysis for their specific branch of the transportation sector.The rail sector has, in the last few years, made a more or less large step in the direction of an industry-wide standardization with the formulation of the European CENELEC norm 5012x. Even though the EN 50126 norm addresses the rail industry and its suppliers with a method of consequently employing safety management, it is doubtful whether its usability is improved as compared with the IEC 61508, which builds its foundation.Likewise, in the automotive industry there have been aspirations for some time to standardize safety-related hardware and software. In the mid 90's, for example, MISRA drafted development guidelines designed to facilitate the standardization of safe software in the automotive sector. Building on that, the FAKRA drafted an adapted version of the IEC 61508 for the automobile sector (ISO WD 26262), in order to drive the standardization of safety-influencing activities.The purpose of the contribution is to give a clear and well structured overview on existing standards supporting the development of safety relevant transportation systems.