The 18th Workshop on Algorithmic Approaches for Transportation Modeling, Optimization, and Systems (ATMOS) is an annual event that aims at bringing together researchers and practitioners who are interested in all aspects of algorithmic methods and models for transportation optimization; it is part of the ALGO conference cluster. This year, ATMOS took place on August 23 and 24 at Aalto University in Helsinki. It featured 16 talks in six sessions on railway optimization, robust optimization, timetabling and line planning, individual traffic, game theory, and vehicle scheduling. Ralf Borndörfer, Marika Karbstein, Christian Liebchen, and Nils Lindner won the ATMOS 2018 best paper award for their article "A Simple Way to Compute the Number of Vehicles That are Required to Operate a Periodic Timetable". The price was sponsored by TomTom, while MODAL sponsored the conference. The photo shows (from left to right) PC chair Sabine Storandt (Universität Würzburg), Nils Lindner (ZIB), Ralf Borndörfer (ZIB/FU/MODAL), and Andreas Linscheid (TomTom). Congratulations!