This paper and its companion describe an experimental study of some aspects of the upheaval buckling of buried pipelines by means of a small-scale model apparatus. After a discussion of relevant literature, the experimental apparatus is described in detail: it involves a thin-walled steel pipe of diameter 6 mm and length 5 m, buried in a bed of artificial soil. The horizontal and vertical profiles of the pipe are measured by an electrical remote-sensing device. Axial load is imparted to the pipe by a screw arrangement and/or by interior oil pressure; and transverse horizontal loading may be applied through a string and pulley. The arrangements for assaying the resistance of the soil to transverse motion of the pipe are described. Results are presented for several tests involving both axial and transverse loading, and cyclic axial loading. The paper concludes with a short discussion.