ault-finding
occurs on the main line. A number of high-profile failures between 2009 and 2011 demonstrated that split-second decisions can cost hours, and FCC has been working to improve its response times to incidents by providing better information to drivers, allowing faults to be isolated and dealt with more quickly. At the heart of this strategy is the
Train Assisted Faults and Failures System (Taffs), a web-based diagnostics tool developed in-house by FCC and named after its creator, rolling stock inspector Mr Keith Taffs. The system guides controllers or engineers in contact with the stricken train through the most logical steps to fix the fault as quickly as possible. It is also used by depot staff to speed up fault-finding on out-of-service trains. “Before Taffs there was no centrally- based system staff could access out on site or at the control centres,” says FCC’s head of engineering production Mr Jason Long. “So we wanted a one-stop shop that staff could look at regardless of their knowledge or experience that would give them a correct diagnosis of the fault in the shortest space of time.” The Taffs home page links to three main options. The
faults and failures menu provides access to the fault trees. These are step- by-step top-down deductive failure analysis tools that allow the controller to establish the cause of a particular problem by relaying questions to the driver over the phone. Taffs contains around 2000 fault trees, all of them written by Taffs himself, covering almost any possible fault on all six train types in the FCC fleet. “With six train types, we knew early on that having a general fault tree would not be enough for ease of use and correct information to be relayed; it had to be location-specific,” explains Taffs. “One fault tree can link into another and you can look back through the steps you’ve visited. The system has a report button so the user can contact the administrator if they feel a step is missing that needs to be included.” Each fault tree starts with a straightforward ‘yes’ or ‘no’ question. Photographs are included to show the position and illumination of indicators on the driver’s desk, and these can be enlarged by the controller to give a clearer idea of what the driver sees. The controller can bypass certain steps in the fault tree if the driver
has already taken them prior to contacting control.
Having identified the fault, the
controller enters the Safety Management System (SMS) menu, which includes information on how to deal with the fault, including all the rules and regulations that might be relevant to the incident. All of the fault trees link to the SMS at appropriate steps and this section also links directly to the latest version of the Railway Safety and Standards Board (RSSB) rulebook. If the train cannot be moved under its own power, the controller can access the assistance matrix which provides movement procedures for the driver, detailing coupling compatibility between the failed and assisting trains, driving position, maximum speed, and the required braking configuration. Instructions for the movement procedure can also be configured according to the direction of travel, telling the driver which cab should be used to move the train. “We built in the assistance matrix because in the past we’ve had incidents where trains have been coupled but the train crew has been unable to establish whether the formation can run with passengers, what needs to be isolated, and what type of coupling is needed,” says Long. Naturally, developing such a
comprehensive system of fault trees is a laborious task - in the case of Taffs it has taken 10 months of intensive work to write and input all the
Pages from the Taffs diagnostics website
which gives access to the fault trees. 39
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