Bridge design

Bridge equipment covers a whole range of devices of very different types, designs and functions, the aim of which is to make a bridge deck capable of fulfilling its function, particularly with regard to users. These devices, which do not have the same durability as the structure itself, are generally not permanently attached to the structure, and fulfil a number of functions. They ensure the safety and comfort of users (roadway quality, transition slabs between embankments and abutments, kerbs and restraint devices, i.e. guardrails, guardrails and barriers), protect the structure and its surroundings (waterproofing, water drainage, protection of embankments by riprap, etc.) and facilitate its smooth operation (support devices, expansion joints). Finally, cornices have a primarily aesthetic role, and any acoustic screens improve the comfort of local residents.

All equipment must be accessible so that its condition can be checked. Compared to the load-bearing structure, equipment is characterized by a shorter lifespan, not only because it is subject to wear and tear or ageing, whether in the case of waterproofing, expansion joints (directly subjected to the effects of traffic) or support devices, but also because over-dimensioning would not offer a better guarantee of durability under certain unfavourable environmental conditions. Provisions must therefore be made to enable them to be easily repaired or, more generally, replaced under good conditions.

Finally, equipment has a real economic importance: it represents 8 to 12% of the total cost of a bridge at the time of its construction, and can, in certain borderline cases, reach 25 to 30%. Above all, they account for around 36% of maintenance costs.