A railing installation apparatus comprises a support platform adapted to be displaced alongside a road. An installation unit is connected to the support platform. The installation unit comprises a feed conveyor unit feeding rails to a carriage unit. The carriage unit is actuated to orient rails to an installation position against posts, and to twist a series of rails connected at one end to the posts to an overlapping position with rails in the feed conveyor unit for end-to-end attachment of the rails.