Railway Standard (en-50128) 474x5x

RAILWAY STANDARD (EN-50128) Presented By: Maryam Zahid [16I-1020] Tooba Yonus [16I-10] Malik Danial Zafar [16I-10] Vania Ammad [16I-1035]

Contents • Introduction • Relationship with other standards • Safety Integrity Levels • Roles and Requirements at SIL levels

• Standards applied to software. Why? • Standards applied to software. How? • Example Application of SIL • Problem of representing software SIL

Introduction

Relationship with other standards

Safety Integrity Levels

Roles and Requirements at SIL levels • Different actor involved in different phases of SDLC • Project Manager (PM) • Requirements Manager (RQM) • Designer (DES) • Implementer (IMP) • Tester (TST) – component and overall testing • Integrator (INT) – integration testing • Verifier (VER) – static verification • Validator (VAL) – overall satisfaction of requirements • Assessor (ASR) – external reviewer

Why standards are applied to SDLC ? • A hazard is a state or set of conditions of a system that,

together with other conditions in the environment of the system will lead inevitably to an accident • Testing not enough • Application of standards on the basis of SIL levels in SDLC allows developers to reduce the probability of a failure leading to an undesired event

How are the standards applied to SDLC ?

1. Software Design and Implementation

2. Verification and Testing

3. Integration and Overall Software Testing

4. Software Analysis Techniques

5. Coding Standards

6. Dynamic Analysis and Testing

7. Functional and Black Box Testing

8. Static Analysis

9. Components

10. Test Coverage for Code

11. Object Oriented Architecture and Detailed Design

Example Application

Step # 1: Fault Tree

Step # 2: Probability of Failure Assigned to root nodes

Step # 3: Overall Probability of Failure calculated

Problem representing software SIL • Difficult to accurately represent a complex system using

Fault Tree • Hazard rates cannot be demonstrated by quantitative analysis • General techniques do not exist • Estimation is questionable