The improvement and maintenance of regional and local roads is the statutory responsibility of each local authority, in accordance with the provisions of Section 13 of the Roads Act 1993. Works on those roads are funded from local authorities' own resources supplemented by State road grants. The initial selection and prioritisation of works to be funded is also a matter for the local authority.
In general, dedicated cycle lanes are not provided on local roads for a variety of reasons; including topography, suitability, visibility, traffic volume and type and so on. It is not possible to give a general estimate of costs involved if a local authority were to consider the provision of such lanes, as the estimated costs depend on the factors above and others, including road surface and compliance with standard design requirements.
As the improvement and maintenance of regional and local roads is a matter for the local authority, I would advise the Deputy to contact the Roads Division of his local authority directly, regarding the feasibility of such works.