The digital Twin (DT) is a technology that can be used to create a virtual representation or model of any physical entity. With the help of DT it is therefore possible to optimise the performance of the virtualised physical system and have a direct impact on increasing its competitiveness, efficiency and productivity, as the data flow can also be bidirectional. The DT of rail level crossings (RLCs) holds great potential for increasing rail safety. With the introduction of digitised components of the railway signalling system, the development of a suitable DT of RLCs is of great importance. Therefore, the aim of this paper is to define the basic requirements for the DT development of RLCs. The paper first analyses the past practises in the development of DTs in railway applications. Furthermore, essential input parameters of RLCs are defined, including the time of closing and opening of RLCs, the warning time, and the operating and blocking times of RLCs. With the aim of reducing the waiting time of road users in the era of train automation and digitalisation, the optimal location of balises and train speed should also be considered. The defined requirements and parameters form the essential elements of the framework for the development of the digital RLC twin.