2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/36366We present two recently obtained solutions of the Einstein equations with spherical symmetry and one additional Killing vector, describing colliding null dust streams.4 pages, 1 figure, sprocl.sty included, to appear in the Proceedings of the ERES98 ConferenceGeneral Relativity and Quantum Cosmologytext