DB Netz AG

High-quality interface specifications with SysML modelling

This article describes an approach that, starting with a coarse view of the system, leads to a detailed interface specification in clearly defined steps. The approach has been developed in the course of many technical discussions in collaboration with railway engineering experts of Deutsche Bahn AG. It is especially suitable for creating high-quality specifications in the complex environment of railway engineering. The procedure has become standard in the project NeuPro of DB Netz AG. Due to its clear structure, the approach is highly suitable for major projects with large teams of specifiers.

Railway network operators are increasingly facing the challenge of integrating subsystems supplied by multiple manufacturers. Currently, many interfaces lack detailed specifications that manufacturers could use for guidance. As a result, entire systems are normally ordered from a single supplier.

Within the project NeuPro, DB Netz AG follows the objective of achieving higher flexibility by creating standardised interface specifications. Berner & Mattner has developed an interface specification approach in support of this goal. The approach, which is presented in this article, is based on modelling with SysML (Systems Modeling Language). It starts with a simplified view of the overall system and then follows a model-based and redundancy-free path with clearly defined steps to arrive at the final interface specification.

TABLE OF CONTENTS

• Introduction
• The challenge
• The solution path
• Interface contex modelling
• Use case analysis
• Use case procedures – functional decomposition of the interface end points
• Communication modelling
• Technical implementation guidelines