INTRO: Chris Jackson reports from Nebraska

REPRESENTATIVES from Alstom Transport and BNSF Railway inaugurated a locomotive test shop at Alliance, Nebraska, on August 24. The event marked the successful introduction of condition-based maintenance to BNSF’s fleet of AC-motored diesel locos used on coal trains from Wyoming’s Powder River basin.

Alstom is responsible for maintaining BNSF’s 434 EMD-built SD70MACs and 40 DC-motored SD40-2s under a 12-year contract awarded in November 2002. Together these account for around half of the locos allocated to Alliance. Others are maintained at the site by BNSF and GE. To date BNSF has outsourced maintenance of around 60% of its 5900-strong fleet.

Maintenance is carried out by BNSF staff under the leadership of a team of 37 Alstom engineers and supervisors. The company is paid for managing the work and supplying all spares on a power-by-the-mile basis, with availability and reliability targets gradually tightening through the life of the contract.

Winning the BNSF contract was an important step in the development of the Train Life Services business, which now accounts for more than 20% of Alstom Transport’s annual turnover.

The Powder River SD70MACs are among the hardest worked locomotives in North America, with three or four locos typically working in distributed power mode to handle coal trains of 15000 to 20000 tonnes. Each duty cycle takes the locos away from home for an average of 11 days, with trains roaming as far as Georgia and northern Florida via run-though agreements between BNSF and other Class I railroads.

Monitoring drives maintenance

In 1999 Alstom business began a research project to assess the benefits of condition-based maintenance. As well as avoiding waste when components are replaced before they are life-expired, moving from a periodic maintenance regime to CBM offers scope to improve availability and eliminate many on-the-road failures by predicting accurately the life of critical components.

Alstom looked at various monitoring technologies, several of which have since been adopted for its service contracts. The Reliability Centre at Alliance brings together many of these techniques to assess the condition of the locomotives as they cycle through the servicing facility every six months. Operational since February, the centre is currently working two shifts per weekday, but this will be stepped up to three shifts by mid-2006. With teams of two machinists and one electrician, the centre is currently assessing an average of five locos per week.

A fixed multi-channel vibration analyser is used to monitor the condition of the diesel engine and auxiliary equipment, backed up by a portable unit to locate possible imbalances and bearing failures. Electrical circuits are tested with a multi-channel meter, and thermography is used to identify damaged wires or faulty joints by the heat that is generated. Ultrasonics are used to detect air leaks, and the exhaust gases are tested for opacity to ensure compliance with environmental protection standards.

An early priority has been to check the condition of the ’Top 10’ components leading to the most frequent or signficant failures, and to set simple red/yellow/green condition thresholds. As an example, all main alternators have been assessed since January 2004 and 81 replaced, leading to a 65% reduction in corrective maintenance costs.

In the longer term, Alstom expects to build up a comprehensive history for each loco, tracking all key components and drawing trends across the fleet. This will allow the development of a ’fragmented overhaul’ programme, where major sub-systems and key components are replaced or overhauled on a cyclic basis during regular servicing, rather than at major strip-downs every six years (Fig 1).

This workload balancing process will involve creating standard manageable tasks to even-out the loading on the workshop staff and optimise servicing times. The changes are expected to improve locomotive performance and utilisation, and to cut costs by forecasting accurately the demand for spare parts, manpower and workshop capacity. This will have spin-off benefits in terms of just-in-time delivery of spares and reduced capital stock holdings. There should also be a significant reduction in the need for reactive and unscheduled work to deal with loco failures.

CAPTION: ABOVE:An SD70MAC is assessed in the new Reliability Centre at Alliance, Nebraska

RIGHT: Checking the condition of the diesel engine and main alternator bearings using a portable vibration sensor

CAPTION: Fig 1. Indicative profile of maintenance costs, based on the FRA 92-day inspection cycle showing how Alstom and BNSF expect the move from cyclic to balanced overhauls to reduce overall maintenance expenditure