Schematic view of the calculation of the dissipation rates expected from SNRs along the lines of sight observed by JT11. A distribution of SNRs with terminal velocities between 30 and 200 km s⁻¹ is drawn out of a simple description of supernovae explosions within the disc and the spiral arms of the Galaxy (panel a). The SNRs are colour-coded according to their terminal velocities. The lines of sight observed by JT11 (red lines) are analysed to count the number of SNR surfaces they intercept and compute the dissipation rates induced by the associated shocks (panels b and c). This calculation is done taking into account the 3D spatial distribution of SNRs, which is shown in projection in panels a and b. Panel c displays a schematic view of a single SNR located at a position A_j. An observed line of sight connects the position of the sun, S, to the position of the background star, B. The number of surfaces crossed by the line of sight for this single SNR (0, 1, or 2) and their inclination angle, i_j, depend on the position of the point, M_j, along the SB line and its distance to A_j compared to the SNR radius.