BYLINE: Viko Giljevic

Project Manager, Croatian Railways

Harry Aghjayan

Consultant, Canarail

AT THE START of this year, Croatian Railways accepted the final rebuilt locomotive to be modernised in a two-year programme covering 20 diesel and 15 electric units. The work has been undertaken by two firms in Zagreb, boosting the local economy and increasing their expertise and skills.

After the break-up of the Yugoslav Federation in the early 1990s, studies found that HZ had more motive power than it needed, but much of the fleet was neither efficient nor in good condition. However, two classes of loco were identified which, if rebuilt at a reasonable cost, could provide the basis for a new motive power fleet. The big question was to rebuild or replace.

With support from EBRD and IBRD, HZ began in 1998 to develop a programme that would bring its assets back to good condition, produce locomotives to meet its needs for the next 15 to 20 years, and introduce the latest technology where feasible to reduce fuel consumption, boost reliability and availability and improve crew working conditions. The cost had to be kept below 50% of replacement value, nominally US$900000 for diesel locos and US$800000 for electrics. The work had to be completed in the shortest possible time, ideally within two years or less.

The rebuild specification was developed over the next two years, and made available to potential tenderers. It covered two main elements: general overhaul and modernisation. HZ wanted a full post-production warranty of one year, plus a reliability level of two attributable road failures per 150000 loco-km for the diesels or 200000 km for the electrics. Availability was to be at least 95%, and the contract would include penalty clauses.

As advisor to both HZ and EBRD, Canarail ensured that bank procedures were followed and that the tendering process was fair, open and successful. EBRD’s Transport Team headed by Mrs A Lukasik provided valuable support throughout the entire programme.

Diesel locomotives

In 2001 Turner Rail Services of Aberdeen was selected as prime contractor for the refit of 20 General Motors-built G-26 Co-Cos of 2200hp, which dated from 1973. GM-EMD and TZV-Gredelj of Zagreb were appointed as subcontractors. Six workstations were set up at TZV’s workshop in Vukomerac, to put the stripping, rebuilding and testing onto a production line process as far as possible.

TRS and TZV set up material management sites to control and distribute spares from the UK, USA, Croatia and elsewhere in Europe. TZV’s project team designed certain elements, including a new cab, relocation of the air brake and other control systems, and reworking of the engine cooling system to accommodate AC-drive fans and new bonded radiators.

EMD provided drawings and addressed issues such as fitting an AC alternator for the new auxiliaries, air flows to the motors and radiators, and application of control electronics to replace mechanical relays.

The first rebuilt loco was accepted in July 2002, and the fleet has now accumulated more than 425 weeks in revenue service. HZ has diagrammed the locos to cover over 11000 km per loco per month, mainly on non-electrified lines to the Adriatic coast. Average availability to the end of April 2003 was 97·4%, with the mean distance between road failures reaching 78000 km.

Electric locos refitted

As original builder of the HZ Class 1-141 electric locomotives, Zagreb-based Koncar was selected to modernise them. As with the diesels, the objective was to improve reliability and availability, and to reduce operating and maintenance costs, by the introduction of modern technology.

One key improvement was conversion from diodes and tap-changers to thyristor controls. The traction motor current and voltage control was upgraded with more modern wheelslip protection and automatic speed control, and the dynamic and pneumatic brakes better co-ordinated. An ergonomically-designed air-conditioned cab fulfils modern safety requirements and improves working conditions for the drivers.

An IGBT-based static converter with more outputs was provided to power the auxiliaries, which now have asynchronous three-phase drives. The main compressor has been changed for a screw-drive unit with an air dryer.

A microprocessor control system incorporating a Train Communications Network has replaced the previous relay equipment. As well as simplifying the control circuits, the system provides better displays in the cab and full monitoring of all functions, allowing easy diagnosis and rectification of any faults. Performance data can be downloaded to a laptop for use by maintenance staff.


We believe that the programme has demonstrated how railways and suppliers in Eastern Europe can perform quality work and meet today’s commercial requirements for budget control and schedule compliance. Older locos can be rebuilt economically and effectively, saving some US$20m in capital expenditure compared to buying new.

Success can be attributed to several factors. Risk was minimised by choosing loco types which could be upgraded using elements that had been proven elsewhere, and involving the original manufacturers. All parties worked well together, with complimentary skills. Forward planning was carried out to the greatest level of detail possible, and the skilled personnel of the site teams were all experienced locomotive engineers, technical and project staff.

Potential problems were identified and dealt with at an early stage, avoiding delays during the rebuilding. Technical assistance and training issues were kept out of the production programme, as ’fuzzy’ side issues can affect the relationships between the participants. Without them, responsibilities remain clear and objectives measurable.

CAPTION: The refurbished GM-EMD diesel locomotives (above) include a new cab structure (left) developed by TZV at Vukomerac

CAPTION: HZ’s 15 Class 1-141 electric locomotives have been refurbished by Koncar and fitted with thyristor controls