Author: Paul MacDonald, Kildare National Roads Office The Trans-European Transport Network (TEN-T) is a combined road, rail and maritime transport network which integrates the European Union. It was initiated in the 1990s with the unification of Europe and was developed from the existing transport infrastructure with the motorway network being an important element of the TEN-T transport network. The development of Europe’s motorway network commenced on an experimental basis in the 1920s  in Italy, France and Germany. With the end of the Second World War, when Europe was divided between the western European states and the eastern bloc states, the widespread development of Europe’s motorways commenced in the western states during the 1950s. The motorway developments were driven by the inherent safety and economic advantages of an integrated road network. The design and construction characteristics of these motorways required pioneering approaches to ensure they facilitated safe transport, were resilient in operation and were visually integrated into the landscape. The close co-operation between western Europe and the United States at the time, in terms of sharing design and construction standards, thus ensured that project risks were mitigated on new schemes. This process was facilitated through the international site visits which took place between engineers within western Europe and the Atlantic region. The major motorway developments took place in those western European states with the greatest populations including West Germany, France and the UK. Given that Germany is located at the centre of Europe, many of the key TEN-T routes are those autobahns which were developed in West Germany during the post-war years.

Rhine Alpine TEN-T Route: A3 Hollandlinie autobahn, Germany/Holland

The A3 Hollandlinie project involved the development of the A3 autobahn route from the Dutch-West German border along the Rhine Valley to the Ruhr industrial region. The A3 linked the Netherlands to the Ruhr region onto Bavaria and into Austria. The A3 Hollandlinie project was part of a joint Dutch-West German road improvement project linking Utrecht in Holland to the Ruhr with the Dutch and German sections completed under a joint road administration framework. This was indicative of the post-war international co-operation in road planning within western Europe. The key challenge for the A3 Hollandlinie project in terms of route selection was the combination of topography and geology along the valley of the Rhine. The new route was located on the eastern bank of the Rhine between the river marsh lands and the higher valley ground just further east. In order to ensure adequate foundation support, the route required a cut into the higher ground terrain particularly near the Dutch-West German border, where the earthworks cut straight through the Eltener mountain and the vertical road profile reached a maximum height of 82m above sea level.

A key constraint for the A3 autobahn (Rhine-Alpine TEN-T Route): Rhine River marshlands

Initially the scheme included for six interchanges from the border to the end point at Oberhausen in the Ruhr; however, three extra interchanges were also included for near the industrial areas to accommodate future development. The scheme was completed in 1965 and today the original A3 autobahn forms part of the important north-south Rhine Alpine TEN-T motorway linking from Holland and Germany into Switzerland and Italy.

Rhine-Danube TEN-T Route: A3 Regensburg-Passau autobahn, Germany

The construction of the A3 autobahn from the Ruhr area into southern Germany followed on from the pre-war autobahn works in the area. The pre-war autobahn was located near the Bavarian Forest mountains just north of the Donau River between Regensburg and Passau, near the German-Austrian border. In the 1960s the route selection for the new A3 route considered a new corridor south of the Donau River on less undulating terrain. This route was discounted, however, given the impact on prime agricultural lands and its proposed location beside the existing regional route No 8. The location of the new A3 autobahn north of the Donau enabled parts of the older route to be integrated into the new scheme. The pre-war autobahn did not cross the meandering Donau as it had been designed with sharp curves and higher gradients to avoid the need for a river crossing. The pre-war route consequently reached a maximum vertical altitude of 535 metres at the Bavarian Forest mountains. These geometric features were not considered acceptable, however, for the new A3 in terms of driver comfort and noise prevention objectives. Therefore less severe geometric features were adopted for the new A3, which shortened it by three kilometres and reduced the highest elevation point to 515m. Two new bridge crossings were required at the Donau. The integration of the new A3 route into the scenic landscape was a key aesthetic consideration which influenced the geometric features chosen for the route. This ensured political support for the project in West Germany and Austria given the sensitivity of the alpine mountain region. The horizontal curves on the A3 autobahn were generally greater than 1,100m in radius while 40 per cent of curves were 4,000 to 5,000m in radius. The use of these large curves combined with gradients of one to two per cent resulted in a natural flowing road alignment appropriate for the landscape. While this achieved the aesthetic objectives for the A3, the long curves did however create a possible risk of aquaplaning for cars during rainfall at the flatter transition points. This safety challenge was addressed by specifying a minimum longitudinal gradient of 0.7 per cent which ensured that surface water drained effectively. Today the original A3 Nurnberg- Regensburg-Passau autobahn forms part of the important east-west Rhine-Danube TEN-T link from Germany into Austria, Hungary and Romania.

Scandinavian-Mediterranean TEN-T Route: A7 Hamburg-Wurzburg, central Germany

The division of Germany after 1945 created a challenge in terms of spatial planning of autobahn routes in West Germany. The elongated shape of West Germany was best served by a central spinal route with the A7 autobahn being the key north-south link running from Denmark and the northern lowlands of West Germany down into the southern mountainous region. The A5 autobahn linked to the A7 at Bad Hersfeld in the centre of the country and formed an important link to Frankfurt and Basel in Switzerland. The key challenge for the A7 autobahn in terms of route selection was the topography of the Rhon mountains which ran diagonally from Heidelburg over to the border with East Germany. The route crossed the Rhon mountains diagonally at the Sinn River valley. The A7 route options were further constrained by land use either side of the crossing point where the road had to negotiate the narrow corridor between a military base and the Bad Bruckenau tourist spa resort. In terms of interchanges, the pre-war cloverleaf interchange at the A7/A3 autobahn junction included sharp horizontal curves, one of which was found to be inadequate for the new geometric standards, hence the need for a direct link from the A7 autobahn southbound to the A3 autobahn eastbound. In terms of environmental impacts, the maximum gradients were specified at four per cent to ensure that vehicle noise on steeper gradients was minimised for residents in the Rhon mountains. Today the A7 autobahn forms a key link in the Scandinavian to Mediterranean TEN-T network which links the Scandinavian countries to Denmark, Germany and Italy while the A7/A3 junction links the Scandinavian-Mediterranean, and the Rhine-Danube Ten-T routes together.

Rhine Alpine TEN-T Route: A3 Brussels-Liege, Belgium

The development of motorways in Belgium were driven by increased traffic volumes which quadrupled from 1949 to 1965 and led to an exponential increase in accidents. The 1951 highway plan focused on industrial links, particularly between Antwerp port and the industrial region at Liege. The plan also aimed to integrate the Belgian motorways into the original Trans-European Network as proposed by the European Economic Community at the time. The spatial layout of Belgium with Brussels at its centre led to an emphasis by planners on radial routes coming from Brussels. This approach changed towards planning for a grid road system which bypassed urban areas in the late 1960s, this reflected the debates in the United States at the time which influenced the thinking of engineers such as Henri Hondermarq, the head of the Belgian road authority. The Belgian engineers visited the US to learn about concrete slip-form pavement technology, in use at the time on the US interstate system. The A3 Brussels-Liege route was constructed using the same concrete slip-form pavement in the 1970s. The A3 autoroute now forms part of the Rhine-Alpine TEN-T Route.

Atlantic TEN-T Route: A10 autoroute Paris-Bordeaux, France

In France the A10 autoroute motorway was proposed in the late 1950s as a key transport link from southwest France to Paris. The northern section from Paris to Tours was initially proposed on a western route option near Chartres and Le Mans in 1958. In July 1967 the transport ministry announced an alternative eastern route between Paris and Tours which was closer to the city of Orleans. The rationale for this alternative A10 route was based on the economic imperative of developing the Loire Valley region at Orleans and Tours. The second section of the A10 autoroute from Paris to Bordeaux had two main alternative route options. The first route was closer to the Atlantic coast linking Poitiers to Bordeaux. The second option was further inland through the historic district of Charente. The two options divided public opinion in the region. In 1973, Minister Michel Feves confirmed the Atlantic coast route option for the A10. This outcome had resulted from: strong lobbying by the coastal communities for the coastal route; the greater traffic volumes which would be served by locating the A10 route near the coastal region; and the potential to link to other coastal autoroutes. With the decision to locate the proposed A10 near the Atlantic coast, consideration was given to constructing a long bridge over the Gironde coastal estuary; however, this was discounted due to the excessive cost of this structure. The A10 route was finally located parallel with the Gironde estuary thereby avoiding the need for a bridge crossing north of the city of Bordeaux. The A10 autoroute forms the main section of the Atlantic TEN-T route linking Spain to France and Germany.

North Sea Mediterranean TEN-T Route: M6/M40 motorway, UK

In 1945 the UK adopted a new motorway design standard based on a customised combination of the American, German and Italian geometric standards. The first motorway in Britain was the M6 Preston bypass which was a key link between Scotland and England. The key challenge for the M6 Preston motorway project in terms of cross section was the debate over whether to provide two or three lanes as traffic studies were only being developed as an academic discipline at the time. The decision was taken to build a two-lane motorway; however, the M6 Preston bypass was at capacity within eight years of opening and required an upgrade to three lanes. This was the inevitable outcome given the lack of predictive traffic models for the scheme. The engineers copied some of the cross-sectional features of the pre-war German autobahn system which many British officials would have seen in Germany in 1945. This included the use of soft grass shoulders. These soft shoulders required pavement upgrading to hard shoulders five years later as heavy vehicles became immobilised in the shoulders and water penetrated to the carriageway subgrade leading to pavement deformation. The use of temporary macadam running surfaces, to allow for post-construction settlement, was also revised due to damage caused by heavy vehicles in low temperature conditions. The permanent surface course was applied within 12 months of the road opening. The public relations on the M6 Preston bypass was considered to be exemplary, particularly the use of models of the scheme to inform the general public. Another key motorway project on the TEN-T Network was the M40 motorway from London to Birmingham. The M40 was designed as a three-lane motorway from Junction 1 near London to Junction 8A near Oxford. The concrete pavement surface was machine grooved to increase skid resistance and disperse rainwater to prevent the risk of aquaplaning. The use of pioneering motorway transport networks also created a challenge in terms of driver behaviour due to excessive speeds on the new routes. This led to the introduction of a maximum speed limit of 70 miles per hour on motorways in the UK. Today the M6 and M40 motorways form part of the North-Sea Mediterranean TEN-T route linking Britain to Belgium and France. The peripheral status of Britain as an island underlines its need for an efficient TEN-T road network linking to the European mainland.

North Sea Mediterranean TEN-T Route: N7/M7 motorway, Ireland

In Ireland, the N7 national route linking Dublin and Naas was the first section of dual carriageway constructed in the country. It was built in sections during the late 1960s. The first motorway in Ireland, the M7 Naas bypass, extended from the Dublin-Naas dual carriageway to provide traffic relief for Naas and was opened in 1983. The N7/M7 national route to Cork and the M1 motorway to Belfast constitute the North Sea-Mediterranean TEN-T network on the island.


The widespread development of Europe’s motorways after 1950 was important for the later development of the Trans-European Transport Network which integrates the European Union. The challenge of designing and building these motorways was addressed through the framework of evolving engineering standards, based on the operational performance of the motorways. The development of Europe’s motorways led to the evolvement of not only of the TEN-T motorway network but also a new body of engineering knowledge in relation to highway design and construction within the Atlantic region.