1103 Copyright © 2014, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. Chapter 54 DOI: 10.4018/978-1-4666-4301-7.ch054 The Role of Formal Methods in Software Development for Railway Applications ABSTRACT Formal methods for thirty years have promised to be the solution for the safety certifcation headaches of railway software designers. This chapter looks at the current industrial application of formal methods in the railway domain. After a recall of the dawning of formal methods in this domain, recent trends are presented that focus in particular on formal verifcation by means of model checking engines, with its potential and limitations. The paper ends with a perspective into the next future, in which formal methods will be expected to pervade in more respects the production of railway software and systems. INTRODUCTION The challenges posed by the new scenarios of railway transportation (liberalization, distinction between infrastructure and operation, high speed, European interoperability,...) have a dramatic impact on the safety issues. This impact is coun- terbalanced by a growing adoption of innovative signaling equipments (most notable example is ERTMS/ETCS) and monitoring systems (such as on board and wayside diagnosis systems). Each one of these devices include some software, which in the end makes up the major part of their design costs; the malleability of software is paramount for the innovation of solutions. On the other hand, it is notorious how software is often plagued by bugs that may threaten its correct functioning: how can the high safety standards assumed as normal practice in railway operation be compatible with such threats? The employment of very stable technology and the quest for the highest possible guarantees have been key aspects in the adoption of computer- controlled equipment in railway applications. Formal proof, or verification, of safety is therefore seen as a necessity. Alessandro Fantechi Università degli Studi di Firenze, Italy