How about Workington North. The station opened in November 2009 and closed in May the next year, - just 180 days. It took 6 days to build and apart from the bare rectangle of land that was the gravel car park, to a casual visitor there is no trace of its previous existence. Arguably it wasn't a 'significant' investment in pure financial terms, but it was presumably greatly appreciated by the residents and businesses of the area.
It was built from scaffolding, so is stretching the definition of "infrastructure" a little!