Highway Structures

Transport networks are supported by a wide range of different structures. They form a vital part of transport infrastructure and the smooth running of the network is dependent on them operating and remaining in a safe condition, available for use.

Over the last decades many structures have started to show signs of deterioration as a result of increases in both the volume of traffic and the weight of vehicles and material degradation as a result of environmental conditions.

For structures in need of repair there are a variety of options available to engineers. These range from weight and lane restrictions to major repairs and strengthening or even replacement. Selecting the most appropriate option requires detailed knowledge of the condition of structures, which is obtained from inspection and testing to diagnose the cause and extent of problems and to identify any hidden reserves of strength. Detailed knowledge of options is required to enable them to be properly evaluated. Finally, it's necessary to have an understanding of the broader impacts of any action that may be undertaken - in particular, disruption to traffic.

The deterioration of traditional materials used in highway structures has led to an increase in the use of new materials, specifically fibre-reinforced polymers. The introduction of new materials requires knowledge of their structural behaviour, particularly when used in combination with other materials, and their long-term durability.

Over recent years there's been increasing emphasis on managing the structures stock as a whole, rather than individual structures. This enables decisions to be taken which provide the optimum benefit to the structures stock. These systems take account of both current and future needs and consider the social and environmental impacts of any decisions as well as the economic costs.

TRL has been undertaking structural research for over 30 years and is responsible for much of the research that underpins the standards and advice on design, construction and maintenance of the structures on the trunk road network. Capabilities include the following:

• in-depth knowledge of the content of the standards and advice notes for highway structures - TRL has undertaken much of the research that underpins these documents and helped produced the documents themselves
• TRL's large-scale testing facilities are used to determine the performance of full-scale structural components and to quantify reserves of strength in a number of different types of structural detail and on components removed from redundant structures
• TRL has undertaken load testing on-site on in-service structures to determine their actual performance and on redundant structures which have been tested to failure
• inspection, testing and monitoring of structures - TRL has undertaken studies to evaluate new testing methods both in the laboratory and on-site
• knowledge of the deterioration mechanisms in different types of structure - much of this is based on long-term studies that have been undertaken in TRL's facilities on-site
• understanding of the effectiveness of different repair methods, based on monitoring the performance of repairs in service as well as field and laboratory trials
• experience of management systems through participation in international projects on structures management and the development of a management system undertaken in conjunction with practising bridge engineers
• acoustic monitoring of structures using SoundPrint®

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