It has been proposed to use horizontal cone penetration tests froma tunnel boringmachine to obtain additional information on the soil in front of the TBM. This article gives an overviewof various investigations into the feasibility of such a technique. The execution of the test as well as the interpretation of the measurements are considered. Tests from a medium sized TBM show that horizontal CPTs can be executed in a practical manner, that the measurements can be interpreted and the results used to improve control of the boring process. Tests performed in a calibration chamber show slight differences between CPT measurements taken in a horizontal and a vertical tradition. It has been shown that in medium dense sands the horizontal cone resistance can be 20% larger than the vertical cone resistance. This information can be used to fine-tune the test interpretation@en