Until 1979, highway bridges in Ontario, Canada, were designed to the American Association of State Highway and Transportation Official (AASHTO) specifications, which required the deck slabs to be considered in pure bending. The term deck slab is used in this article to describe the concrete slabs of girder bridges. Extensive research sponsored by the Ministry of Transportation of Ontario (MTO), Canada, and conducted with the help of both laboratory models and field testing of bridges has confirmed that deck slabs, because of an internal arching action, are much stronger than slabs in pure bending. This research also confirmed that the amount of steel reinforcement in deck slabs can be reduced considerably by taking into account the internal arching action.

The Strategic Highway Research Program (SHRP) has investigated more than 60 concrete and structural products. To stimulate the use of selected products by state highway agencies, the Federal Highway Administration (FHWA) is using a "Showcase" to demonstrate these and other new product technologies. Products selected for showcasing include those contributing to the production and performance evaluation of higher quality concrete.

It is a well known fact among highway engineers that more than 40 percent of the United State's 574,729 inventoried highway bridges are classified as structurally or functionally deficient. Specifically, the most serious type of deterioration is in the reduced carrying capacity of 22,064 reinforced, prestressed concrete bridges. In most cases, structural deterioration is triggered by steel corrosion, especiallly in the presence of roadway deicing salts.

The Metropolitan Expressway Public Corporation (MEPC) is now constructing a triple-carriage highway (Bay Shore Route) in Yokohama City, Japan. This project includes a prestressed concrete viaduct over a national highway (Route 357) near Torihama Town. The viaduct is made of continuous, three-span box girders monolighically encased in the caps of the two central piers.

Attempts to improve construction and reduce the costs of bridges and docks in Alaska resulted in the development of numerous design solutions, including those of research and development. Many of these efforts brought about the use of precast concrete deck panels in conjunction with structural steel girders. These individual components of relatively light weight permitted contractors to reduce mobilization and equipment costs at remote sites.