'Safe Software' Need Not Be an Oxymoron

Computer-based controls of transportation systems, industrial plants, sundry machinery, and consumer items became ubiquitous in the last quarter of the twentieth century. The microprocessor -- the heart of the microcomputer, microcontroller, programmable logic controller, and indeed today’s workstations, servers, and even mainframes -- is the enabling technology behind these digital control systems. The behavior of computer-based controls is determined by the combination of kernel, operating system, and application software that the controlling computers execute. Today’s multi-gigahertz and -gigabyte computer-hardware technology has seen a concomitant growth in the size and complexity of software development environments, i.e., in specification tools and languages, compilers and programming languages, and semi-automated tests. The quantitative aspects - size, speed, complexity - of the contemporary versions of these technologies have given rise to the general impression that hardware software architectures and software-development methodologies have changed fundamentally, i.e., qualitatively, from those of the 1960s. This is not the case, even for the vast majority of computer-based control applications in transportation, aerospace, and factory automation. To paraphrase a famous line in a famous film, the methodologies are the same, only more so. The notions safe software, along with those of secure software and trusted software, concern the real-world function, purpose, or ‘meaning’ of computer programs. Though not the stuff of daily headlines (but certainly the stuff of occasional, sensational ones), the correctness of software - it does what it’s supposed to do - has been the subject of great effort from Computing Science’s inception. This paper elaborates the issue of software-correctness, as it manifests itself in safety-critical (vital) transit applications; and describes emerging Best Practices in this area, including the safety-critical project life-cycle and an approach to safety certification. The paper also addresses cultural and economic influences that affect the education and training (a distinction with a difference) of the Software Engineering labor force, and that affect transit properties and their contractors, and provides an example risk assessment of the NYCT Canarsie Line safety-critical Communication Based Train Control (CBTC) transit system.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/oclc/7p
• Supplemental Notes:
  • Full conference proceedings available on CD-ROM.
• Corporate Authors:

  American Public Transportation Association

  1666 K Street, NW, Suite 1100
  Washington, DC  United States  20006
• Authors:
  • Hacken, G
  • Georgiadis, S
  • Cutright, E
  • Ghaly, N N
  • Khalili, N
  • Sabatier, D
• Conference:
  • Rail Transit Conference, 2005
  • Location: Pittsburgh Pennsylvania, United States
  • Date: 2005-6-5 to 2005-6-8
• Publication Date: 2005

Language

• English

Media Info

• Media Type: Print
• Features: Figures; References;
• Pagination: 13p
• Monograph Title: Rail Transit Conference Proceedings, 2005

Subject/Index Terms

• TRT Terms: Control system applications; Digital computers; Education and training; Mainframe computers; Microprocessors; Safety and security; Security; Software; Software packages; Technological innovations; Transportation planning
• Geographic Terms: New York (New York)
• Subject Areas: Data and Information Technology; Education and Training; Railroads; Security and Emergencies;

Filing Info

• Accession Number: 01002139
• Record Type: Publication
• ISBN: 1931594155
• Files: TRIS
• Created Date: Jul 19 2005 10:17AM