A man attacked two officers and went on a "violent rampage" when they asked if his journey was necessary, police said.
Nelson Nelson, 29, assaulted the pair at Nottingham railway station on Saturday and then charged at police with a makeshift club, British Transport Police (BTP) said.
Nelson, of Aldridge, West Midlands, pleaded guilty to seven charges at Nottingham Magistrates' Court.
Both BTP officers needed hospital treatment for their injuries.
Nelson was asked if his journey was essential as he boarded a train and he "took exception to this" and became abusive, BTP said.
As they tried to take him away he punched both officers in the face, knocking one unconscious.
He dragged the other in to the road, in front of an oncoming bus, and then ran off to a building site opposite the station, the force said.
When more police arrived he charged them with a "plank of wood with nails in it" and hit a police dog "multiple times" with it before he was arrested.
Ch Insp Gareth Davies said: "There is never an excuse for this sort of behaviour, but it's all the more shocking to think this violent rampage began after Nelson was simply asked if his journey was essential."
Nelson, of Stonnall Road, admitted two counts of assault, two counts of actual bodily harm, one count of possession of an offensive weapon and one of possession of a knife, and another count of causing unnecessary suffering to a protected animal.
He is due to be sentenced on 27 April.