Alternative road designs with overtaking restrictions and periodic overtaking lanes, so-called 2+1 roads, are used as low-cost alternatives to increase safety on two-lane roads. However, there are potential implications of these road designs on the quality of service. To ensure acceptable quality of service, there is a need for trac analysis tools to support the design of 2+1-roads. This paper presents an extended version of the RuTSim microscopic trac simulation model including models of characteristic speed adaption, overtaking and merging behaviour on 2+1 roads. Numerical experiments are used to verify that the model reproduces fundamental characteristics of trac on 2+1-roads