AROUND 80% of electrification work has been completed on Hellenic Railways’ trunk line between Athens and Thessaloniki, and the project is due to be finished by the end of 2005.

If that date is met, nearly 10 years will have elapsed since signature of the contract to wire the 517 km route at 25 kV 50Hz. Bids were called in 1995, and the deal was concluded in the following year with a consortium that now consists of Balfour Beatty Rail SpA, Bombardier Transportation and ABB Hellas. The group is working for Ergose SA, the Hellenic Railways subsidiary responsible for major projects and new construction. The contractors set out from the north and worked south to Larissa, from where work is proceeding towards Athens.

The work forms part of a major programme to upgrade the route between the capital and the largest city in northern Greece for high speed running, with much of the line rebuilt to permit 200 or 250 km/h. In some cases spectacular sections of new double track alignment replace sinuous single track on the present route.

Originally, the contract was to be completed in 60 months, but delays to the civil engineering work triggered renegotiations which saw a further 52 months added. At 2003 prices, the contract is worth €91m, according to Dr-Ing Carlo Catteneo, Director of Marketing & Sales at Balfour Beatty Rail SpA.

There are 11 substations, two of which have been completed. All are similar and include two 15MVA transformers. Two types of contact wire are being used. Around 50 km is being wired for trains to run at a line speed of 200 km/h, with the rest suitable for 250 km/h. A bronze messenger wire with a cross section of 95mm2 is used, and the contact wire has a cross section of 107mm2. Both are tensioned at 14 kN using a single tensioning device for both conductors.

Composite insulators are used with a glass fibre and epoxy resin core and silicon sheds, similar to those used on high speed lines in Italy. Poles have a flanged base and in contrast to those in Italy have more spaced C-irons to give a higher stiffness. Aluminium contact line cantilevers are of the inclined strut type with a horizontal upper frame. Conductive droppers are formed of a bronze string with a 12·5mm2 cross section, with copper terminals for both the string and the messenger wire.

TABLE: Table I. Athens - Thessaloniki 25 kV 50Hz electrification

Height of contact wire over rail top mm 5750

Maximum span length m 63

Pole to rail distance mm 2280

Tensioning length mm 1200

Encumbrance mm 1400

Overlapping On 3 spans

Droppers per span 7

CAPTION: Newly-completed 25 kV 50Hz electrification on OSE’s Athens - Thessaloniki trunk line