The paper reports on the measurement of an arching effect over a large diameter flexible culvert. An arch shape culvert, 51 ft (15.5m) in span, was erected and covered by a 44 ft (13.4m) high embankment. An extensive instrumentation program was laid out in order to check the mobilization of an arching effect during construction by measuring displacements, earth pressures, and stresses in the steel. The instrumentation data indicated that a large portion of the load due to the weight of the soil above the structure was transferred to the adjacent area.