Based on a different principle than the beam is the arch bridge. In the beam bridge the load is transmitted vertically to the supports. The arch bridge pushes outward against its supports. They must be heavy to resist the horizontal thrust of the arch. The arch may be fixed, with each end rigid, two-hinged, with a hinge at each support, or three hinges at its crown. The hinges permit movement because of loads or temperature changes.

Arch bridges differ according to the way in which they carry the horizontal roadway. In the deck arch the road is carried above the arch which supports it. In the half-through arch the road cuts through the arch. Its middle section is hung from the arch, and its outer sections are supported by the arch. In the through arch the road is suspended from the arch. An arch bridge of rectangular shape is the rigid frame. It is used from shorter spans, such as in highway and railway grade separations. Its horizontal span is made in one piece with the vertical supports. The rigid frame is made of steel or reinforced or prestressed concrete.