Field measurements were carried out on a steel culvert in Poznan in Poland. The steel culvert is a pipe arch with a span of 8.9 m, a height of 7.76 m, and a soil cover of 1.8 m. This road culvert and a parallel pedestrian steel culvert were used to replace a severely corroded concrete railway bridge. The steel culverts were erected and backfilled without closing busy track railway. The steel culverts were instrumented to measure steel stress and deformations during backfilling and load testing. Two locomotives with a total weight of 2360 kN were used for load testing. The measured steel stress and displacements during load testing were recorded with the locomotives placed at various locations (static) and also during braking. The steel stress and deformations from live loading were small compared with the steel stress and deformations during backfilling. The measured steel stress from live loading was less than 7 MPa, and displacements were less than 0.5 mm. The measurements also show that long-span pipe arches perform well without longitudinal thrust beams and circumferential stiffening ribs. Long-term measurements were also taken in the period after the end of construction from March 1998 until December 2000 and indicated very good performance of the structure. The structure received a prize for engineering excellence due to innovative construction and aesthetic appearance.