Integral bridges can be defined as bridges without joints. They span from one abutment, over intermediate supports to the other abutment without any movement joint in the deck. The advantages of integral construction are greater durability and lower maintenance costs when compared with jointed bridges.
Integral bridges are not new, masonry arches being a typical early example. The bridges on the first section of the M1 constructed in 1959 are examples in reinforced concrete. Many more recent bridges were built with simple spans and joints at intermediate supports and abutments. A survey of the performance of 200 highway bridges in 1989 confirmed that most bridge joints leak and consequently the areas of the abutments, piers and deck soffits are becoming stained and contaminated with chloride from road salts. The Highways Agency (now highways England)recommends that integral construction should therefore be the first option for all bridge decks shorter that about 60 m.
Semi-integral bridges are without deck joints and have the advantages of full integral construction. Bearings are introduced below the deck and an end wall carries the horizontal forces to the soil.