The test facility and the AASHO road test pavement experiments conducted are fully presented and discussed. The behavior and performance of 18 slab and beam bridges under regular test traffic and during accelerated fatigue tests are described. Also reported is an analysis of the fatigue strength of the bridge beams. Field tests and laboratory tests on the fatigue strength of the steel bridges are compared. Tests to failure of the ten test bridges are described. The behavior during the test and under failure of a noncomposite steel bridge, composite steel bridge, reinforced concrete bridge, post-tension prestressed concrete bridge and a pretensioned prestressed concrete bridge is described in detail.