Real Time Kinematic (RTK) is a system that uses the Global Navigation Satellite Systems (GNSS) for accurate positioning in real time. The idea of RTK is to receive GNSS signals with a stationary reference at a known position and using these measurements to correct the positioning data for a rover on another site where you want to determine the coordinates. The Swedish National Transport Administration operates the Project “Stomnät i Luften (SIL)”. The project aims to create a national strategy for the RTK-based core network to achieve a more efficient process for the Transport Administration's commitments to construction projects. Within the National SWEPOS network, the distance between reference stations is typically 70 km. For example, at construction work, additional reference stations are deployed around an actual working area. The purpose of this report is to answer three main questions on how performance is affected by the combination of dense and sparse reference networks, how an optimal densification of the reference network should be designed and how accuracy is affected by the construction project spatial scale We show by simulations that the best locations of reference stations to minimize the measurement error is next to the road. A denser network means we can combine large and small triangles in the network. The best measurements are achieved when the inner triangle is given in principle all weight. In practice it may be reasonable to add some weight to even the outer triangle for robustness reasons. For small construction projects, around 5 km, the simulation shows that the vertical measurement error from the RTK system is 3 mm and an expected total vertical measurement error is around 8 mm when including the contribution from the local rover. For large construction projects, about 70 km, the corresponding values are 5 mm and 9 mm respectively For these situations, there is much to gain in accuracy if the installation of the rover can be done in a way that the “local effects”, such as reflections and partial blockage is minimized . The contributions from the local effects will, however, vary greatly depending on the particular position and assembly. For regional construction projects the vertical measurement error from the RTK system is 10 mm and an expected total vertical measurement error is around 12 mm.