Bridges, overpasses, viaducts, viaducts are all synonymous words. Moreover, they denote very similar construction projects that are widely used by man in their economic activities. To distinguish between these concepts, and this small material is proposed.
Bridge
This is an engineering construction, invented for a very long time. One of the oldest dates from the thirteenth century BC. From ancient times, people began to build bridges to overcome water barriers like rivers, lakes, swamps, etc. Therefore, the word is not only the most used among the proposed ones, but also the oldest. In a broad sense, all the other structures mentioned are bridges, so the answer to the question posed in the title of the article should be “yes”. However, there is a “but.” About him a little later.
Overpass
This is a structure that is being built over another road, but is no longer called a bridge, since there are quite serious differences from it technologically. First of all, they are caused by the fact that when designing an overpass, there is no need to take into account the influence of various natural phenomena associated with the watercourse available under the bridge. Therefore, the principle of creating supports in this case is fundamentally different. We will not delve into technical details, we recall only three factors that the head designers of bridges have a sore head about. This is an ice drift, erosion and a bulk of ships passing under them. An overpass is, in fact, a bridge over an ordinary road. Therefore, we have a different term for this structure. This is a small “but” in the legality of the use of the word “bridge” in determining the overpass.
Overpass
If for the construction of the viaduct it is usually required from two to four spans 10-30 meters long each, then for the construction of the flyover their larger number is usually required. In fact, this is the whole difference between these engineering structures. However, the important point here is that the overpass can cross several types of obstacles at once, for example, it can be a river, a motor road and railway tracks simultaneously, thus combining both a bridge and an overpass.
Viaduct
Consider the following type of bridge. There is another type of obstacle that is fundamentally different from what we have already considered previously. This should include ravines, gorges, hollows. Therefore, the word "overpass" can no longer be used here. This is another type of bridge structure - a viaduct. Consider its features.
The construction of viaducts instead of conventional roads is justified in cases where it is not economically feasible to create a mound. That is, everything is determined by the depth of the ravine, as well as its length in the profile of the available transport highway.
Thus, the difference between a viaduct and an overpass is the absence of a more or less even surface under the bridge. Due to this factor, the uniformity of the supports and spans in this case is no longer suitable. Viaducts are usually very beautiful and majestic structures. For example, the height of one of the pillars of the world's highest Millau viaduct is about 340 meters.
Continuing the theme, we can mention another interesting building, although it has only a distant relation to such concepts as overpasses, roads. We are talking about the so-called aqueducts. This is an analogue of a viaduct, only for transporting water, not vehicles, over the same ravine, river, or other obstacle, usually part of an irrigation system.
Conclusion
Returning to the question posed in the title of the article, we will finally answer it. Yes, an overpass is a bridge by the principle of construction, and no, because it is created not over water barriers, but over a similar road surface. Such is the dialectic.