Do I need to provide the data underlying my dataset/service on the NAP ITS in an open manner?
It is not mandatory to provide open access to the data underlying your dataset or service on the NAP ITS. Only the metadata and a link to your dataset or service need to be publicly visible on the NAP ITS. The data or service that you host on your own website does therefore not need to be publicly accessible. You may ask for a contract or license for access to your data, whether or not in return for payment. If this is the case, you need to indicate this information in the metadata fields for your dataset ‘Contract or license’ and ‘License type’.
For the NAP type SRTI (Safety-Related Traffic Information), however, it is mandatory that you make the category 'Minimum safety information' publicly available (on your own website) and free of charge. This is stated in the European Delegated Act 886/2013 for SRTI:
‘Public road operators, service providers and broadcasters dedicated to traffic information
shall provide road safety-related minimum universal traffic information to end users prior to the provision of any other non-safety-related traffic information. The information service shall be provided in such a way as to ensure the widest reach of end users concerned by the given event or condition referred to in Article 3.’