A railroad track maintenance assembly, comprising: ∘ A sleeper designed to support at least two rails, said sleeper comprising at least one block, ∘ A pad comprising a semi-plastic damping layer designed to be interposed between said block of the sleeper and a ballast; characterized in that ∘ the damping layer has, in the event that a load test is performed, an EPM index in the range of 10% to 25%, preferably in the range of 10% to 20%, and in that ∘ the sleeper has a length less than 2 m 30, wherein the EPM load test is to be performed on a test element consisting of the damping layer, having an area of 300 mm by 300 mm, and comprising the following test steps consisting of: a) establishing at least one test point on the test element, at a site of the test element against which a contour plate, which has a plurality of raised portions, exerts a pressure against the test element with a maximum protrusion of one of the raised portions during test step c); b) determining a starting thickness D0 of the test element in the unloaded state at the test point in a direction perpendicular to a surface of the test element; c) compressing the entirety of test element, which was not subjected to the load beforehand, for a period of 60 seconds between a flat steel plate and the contour plate, the test element being compressed at the test point to 50% of the starting thickness D0 thereof at the end of 60 seconds and the contour plate being pressed with the maximum protrusion of the raised portion of the contour plate against the test element at the test point; d) continuously maintaining, for 12 hours, the compression achieved in test step (c) at the end of 60 seconds on the test element; e) stopping the compression and fully relaxing the test element in a 5 second relaxation interval at the end of the 12 hours according to test step d); f) measuring the momentary thickness D20 of the test element at the test point, 20 minutes after the relaxation interval according to test step e) has elapsed, in a direction perpendicular the surface of the test element according to test step b); g) calculating the EPM index from the starting thickness D0 and the momentary thickness D20 measured in test step f) according to the formula: 100% times (D0-D20)/D0. ∘ A sleeper designed to support at least two rails, said sleeper comprising at least one block, ∘ A pad comprising a semi-plastic damping layer designed to be interposed between said block of the sleeper and a ballast; ∘ the damping layer has, in the event that a load test is performed, an EPM index in the range of 10% to 25%, preferably in the range of 10% to 20%, and in that ∘ the sleeper has a length less than 2 m 30, a) establishing at least one test point on the test element, at a site of the test element against which a contour plate, which has a plurality of raised portions, exerts a pressure against the test element with a maximum protrusion of one of the raised portions during test step c); b) determining a starting thickness D0 of the test element in the unloaded state at the test point in a direction perpendicular to a surface of the test element; c) compressing the entirety of test element, which was not subjected to the load beforehand, for a period of 60 seconds between a flat steel plate and the contour plate, the test element being compressed at the test point to 50% of the starting thickness D0 thereof at the end of 60 seconds and the contour plate being pressed with the maximum protrusion of the raised portion of the contour plate against the test element at the test point; d) continuously maintaining, for 12 hours, the compression achieved in test step (c) at the end of 60 seconds on the test element; e) stopping the compression and fully relaxing the test element in a 5 second relaxation interval at the end of the 12 hours according to test step d); f) measuring the momentary thickness D20 of the test element at the test point, 20 minutes after the relaxation interval according to test step e) has elapsed, in a direction perpendicular the surface of the test element according to test step b); g) calculating the EPM index from the starting thickness D0 and the momentary thickness D20 measured in test step f) according to the formula: 100% times (D0-D20)/D0.