Among the notable activist projects with which Mees involved himself were legal actions attempting to prevent the construction of expensive transport projects contrary to his views on what constituted good public transport policy. In the late 1990s he questioned the legality of aspects of the largest urban infrastructure project in Australia's history, the CityLink tollway system in Melbourne. Mees unsuccessfully contested the building of a marshalling yard and a new tram "superstop" in front of the main entrance to the University of Melbourne's Parkville campus on Swanston Street, and opposed the building of the proposed Melbourne Metro Rail Project tunnel under the centre of Melbourne, on the grounds that much less expensive options are available to boost capacity on the Melbourne suburban rail network. In the early 2000s he also helped to establish the short-lived Public Transport First Party in Victoria, which campaigned in selected electorates on transport-related issues.