Implications of Future Heavier Trucks for Europe’s Bridges

Eugene J. OBrien, University College Dublin
Bernard Enright, Dublin Institute of Technology
Colin C. Caprani, Dublin Institute of Technology

Document Type Conference Paper

Transport Research Arena Europe 2008, Ljubljana, Slovenia


European Road freight transport increased by 38% between 1995 and 2005 and this strong growth seems likely to continue. To address this growth without compromising the competitiveness of European transport, some countries are contemplating the introduction of longer and heavier trucks, with up to 8 axles and gross weights of up to 60 t. However, many roads authorities are concerned about the implications for Europe’s bridge infrastructure. For bridge loading, it is the combination of gross weight and truck length that determine load effects such as bending moment and shear force in the deck. A probabilistic analysis is required to assess whether these proposed trucks will lead to greater maximum lifetime load effects. If this was found to be the case, it would necessitate the strengthening of a great number of vulnerable bridges throughout the continent or it could even prevent the introduction of heavier trucks. This paper reviews the factors governing traffic loading on short/medium span bridges. There is considerable conservatism in the Eurocode traffic loading model. Hence, bridges designed to this or similar modern codes of practice can be shown to be safe in the presence of significant numbers of longer and heavier trucks. Even more significantly, using data from one of Europe’s most heavily trafficked highways, it is shown that the critical loading events are often special permit trucks such as cranes or low-loaders with up to 12 axles. Hence, characteristic load effects are unlikely to be affected by the introduction of longer and heavier trucks.