ERTMS/ETCS Hybrid Level 3 (HL3) was designed to achieve higher capacity and increase the robustness of the railway network cost-effectively. This study evaluates the capacity effect of HL3 on a conceptual level by looking at a scenario with two trains and on a network level. Key performance indicators help evaluate the results of implementing HL3: headway for the conceptual model, and capacity utilization and punctuality for the network level. With the implementation of HL3, two central variables influence the capacity: the length of Virtual Sub-Section (VSS) and the share of Level 2 (L2) and Level 3 (L3) trains in the network. For this purpose, we need to answer the following questions:  

• What effects do different VSS lengths have on the performance indicators?
• How does the share of L2 and L3 trains in an HL3 system affect capacity?
• What are other key factors that influence HL3 capacity evaluations? 

The study uses the simulation tool RailSys, an integrated microscopic planning tool developed by RMCon. A case study on the interaction between two trains examines how various lengths of VSS affect the performance indicator headway. The network scale simulations use a real-world infrastructure and a complete timetable. Two cases examine how the performance indicators capacity utilization and punctuality are affected by the share of L2 and L3 trains in a HL3 system.