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Highways Making order from chaos

Egnatia Complex geology and archeological finds are continuing challenges on Greece's Egnatia highway.

AFrench tourist holidaying in Thessaloniki this summer reported herself highly pleased with a five day coach trip to Istanbul: most of the journey had been on smooth high speed motorway, she said. Until recently a trip across northern Greece involved hours of crawling behind heavy trucks on tortuous winding roads.

After nearly a decade of work the Egnatia motorway project is finally making a major impact.

Some 350km of road is now open - over half the 680km length of the two-lane dual carriageway route.

Most of this 350km is in the flatter, eastern section to the Turkish border but substantial sections of the more difficult mountainous western sector are also running. Many of the 70 tunnels and 40 major bridges are complete, or nearly so.

'We are opening about 80km a year, which is on schedule, ' says Guy Hindley, project director for KBR. The firm was appointed in 1996 to help build the project and to secure funding from the European Union.

Despite good progress, the main project has not been without difficulties, and frequent attention from the Greek press.

The original completion date of 2006 has been put back.

Work must still be finished by 2008 however, because that is when deadlines run out for spending money from the third tranche of the EU Community Support Fund which is financing 50% of the project.

The remainder of the, so far, £3.2bn project comes from the government via European Investment Bank loans.

Delays have been caused primarily by problems of working in the mountains, particularly on some of the more challenging tunnels in exceptionally difficult ground, and hold ups caused by archaeology. The road runs roughly along the route of the eponymous Roman Egnatia highway built in 100BC and also crosses the key territories of Alexander the Great, so the chance of discoveries is high. Numerous ancient sites have been explored, around a dozen needing several years to excavate, holding up work.

'There have also been some contractual disputes which have caused delays, ' says Hindley.

A further revision in bidding procedures is due.

Late delivery of drawings has been another issue and the procurement rules for design are also being changed at present by government. One reason for the delays is simply that Greek design firms, while technically sound, are not as large as many in Europe.

The technical challenges of the mountains especially are great.

The region is the most seismic in Europe, which constrains much of the bridge design and requires additional analysis for failure modes and for soil structure interactions.

For contractors - almost all from Greece, or exceptionally from Cyprus - there are difficulties of access with new haul roads needed on many sites, and difficult winter conditions which can leave the higher sites too icy to work and snowbound for several months.

Inside the dozens of tunnels the weather is less critical but the ground is a problem. The region's geological history has been even more turbulent than its human one and at least as complex.

A series of major thrust plates pushing from the east have been stacked one above the other, creating sudden changes in the rock, from schist to limestone to multi-layered flysch and ophiolitic baslats and dolerites.

The movement has torn the rock in places and left it highly fractured, sometimes pulverised or heavily weathered, and often has folded it over and over, so that the bedding direction can change completely in a metre or two.

On the surface there are large accumulations of erosion debris and the whole area is littered with slips, some ancient and others new and still moving.

In the steepest part of the Pindos mountains this led to a major realignment of a key section near Metsovo. An earlier route line passed mainly through slips in a step valley and when client Egnatia Odos (see box) took over the project this was set on the other side which was more stable.

The difficulties caused are typically shown on one of the shorter of a dozen tunnels on an unfinished part of the central section at Veroia, west of Thessaloniki where the route begins a 5% gradient climb from the plains, across a steep range of hills.

'We suffered a maximum of 400mm of movement vertically and laterally during construction, ' says infrastructure project manager Peter Gibbons.

A massive row of piles with their tops anchored back was used to control the slope higher up and heavy anchoring and grouting stabilised the tunnel.

'Not all the tunnels have problematic ground, ' says Nikos Kazilis, technical director for tunnels on the project. But many do and even in Driskos there were two sections 'squeezing ground' of 200m and 500m lengths respectively in the two bores.

Most of Egnatia's tunnels were either already twin bore or were upgraded following the 1998 Mont Blanc tunnel fire disaster, so they have a safer unidirectional traffic flow.

A few tunnels along is the Anthchori, considered by the project's outside expert consultants Professor Paul Marinos and Dr Evert Hoek to have the most complex geology on the scheme.

'The 680m long tunnel had squeezing ground virtually from the beginning and needed two redesigns, ' says Kazilis. An initial assumption that large boulders in the heavily sheared flysch would act like massive rock proved wrong because they were all 'floating'.

Ground support was increased and temporary and permanent inverts added into the excavation sequence. Most of the excavation is now complete and the tunnel should be ready next year.

While difficult sections are waiting to open, traffic flow will be facilitated by using so-called 'operational Egnatia'.

These are three upgraded sections of the national highway built in the last two years by Egnatia to link completed motorway road sections in three difficult areas, avoiding a difficult landslip section in one case and tunnel problems in another.

Work to be done now includes a major section in the western central area, which has been long held up because of environmental and ecological issues including protection of the European brown bear.

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