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The safety and on-time performance of any passenger rail service depends on the people, technologies and processes that are the basis of its operations and maintenance program. Improving on-time performance while reducing costs would seem to be a paradox; however, First ScotRail, which operates passenger rail services for Transport Scotland, is endeavoring to do just that with its fleet of Class 170 diesel multiple units (DMUs).
At First ScotRail we recognize that the current norm of taking trains out of service for distance or time-based maintenance regimes, as opposed to condition-driven maintenance practices, means that trains are sometimes out of service unnecessarily.
Furthermore, unscheduled maintenance, which occurs whenever something breaks unexpectedly, has an effect that is financially detrimental, and even more detrimental from a public relations standpoint. Passengers rightly expect safe, reliable, comfortable transit services and unforeseen breakdowns have a direct impact on customers and revenues, as well as on costs.
First ScotRail's performance requirements with Transport Scotland include availability and on-time performance measures. In order to move toward a more proactive approach to managing our fleet, to optimize its true value as an asset, we have enlisted Bombardier's support in monitoring the performance of a percentage of our Class 170 fleet using Orbita, Bombardier's predictive maintenance capability.
Orbita combines on-board diagnostic technology, data display and knowledge-management software with a control center staffed with experienced people to predict failures and recommend repairs on an as-needed basis before systems or components fail. Advances in on-board IT at the component level, coupled with advances in communications technology, mean that data can be regularly transferred from each system and component on each vehicle to a Knowledge Control Centre staffed with Bombardier's systems engineers. The data is interpreted by these experts, who identify abnormalities and pinpoint pending failures. This then leads to targeted maintenance recommendations, delivered directly to First ScotRail's maintenance team at the depot.
The First ScotRail fleet is fitted with Mitrac on-board equipment that enables each vehicle to communicate information about the health of the subsystems, such as engines, doors and air conditioning. Mitrac produces two types of data: fault/event codes that indicate that something of interest has happened on the vehicle, and environment parameters that are measures of physical conditions such as pressures, temperatures and speeds.
When an event occurs, such as a train stopping at a station, an event code and a data snapshot are transmitted to the Control Centre. There, the data is converted into information and advice, which is sent back to First ScotRail. For a large fleet such as First ScotRail's, thousands of fault/event codes and environment parameter readings can be transmitted from the vehicles daily into understandable and actionable information. Without Orbita, the sheer volume of numbers would be overwhelming, and there would be a risk of missing important insights into how the vehicles and their systems are behaving.
Patterns of codes received quickly flag failures that need to be investigated and fixed. The maintenance personnel receive a message alert stating the precise nature of the problem via a large screen installed in the depot's communication center. A computer/printer link generates a detailed task sheet, relieving them of the need to plow through masses of data in an attempt to interpret the meaning of what is being reported. This contributes to improvement in the overall operational efficiency.
The ability to predict a failure of a component or system greatly reduces costly downtime, whether the issue is service-critical or not. The information provided allows us to have our finger on the pulse of our fleet all the time. Additional benefits are a greater understanding of fleet performance, prior warning of failures, real-time diagnostic information across a whole range of monitored subsystems and components, and optimized predictive maintenance. Operational information can also be obtained, such as passenger loading, location of trains, distance traveled, system condition, environmental conditions, track conditions and power supply fluctuations.
The results are encouraging. In less than two years, it is already delivering tangible results to the operator and passenger alike as it demonstrates the real value which can be delivered by interpreting fleet data to drive a predictive approach to asset management.
Steve McCredie is depot production engineer for First ScotRail in the UK.
author: Steve McCredie, steve.mccredie@firstgroup.com