The man convicted of shooting dead a road worker operating a stop-go sign has lost his bid to appeal his conviction and sentence in the Supreme Court.

Quinton Paul Winders was sentenced to life imprisonment with a minimum period of 17 years for the murder of George Taiaroa in 2013.

Mr Taiaroa was operating a stop-go sign at a single lane bridge near Atiamuri when he was shot in the head.

Winders was sentenced to life imprisonment and ordered to spend at least 17 years behind bars for murdering Mr Taiaroa, who was shot dead while operating a stop-go sign in Waikato.

The Crown said the shooting followed an earlier minor run-in Winders had with Mr Taiaroa in the weeks before he died.

Winders' lawyer Philip Morgan QC questioned the 17-year minimum jail term imposed, saying there had to be 'calculated planning' for such a lengthy sentence. Read more here.

Winders earlier lost a challenge against his conviction and sentence in the Court of Appeal.