Hayden Kiefer, 19, was arrested last month for vandalising Corrimal railway station and exposing himself in public only hours after he was released on strict court bail for assaulting a driver at Thirroul and threatening a man who witnessed it.

The serial graffiti tagger had been so prevalent in Bulli, he left some residents living in fear, police said in a statement to Wollongong Local Court.

Magistrate Michael Stoddart on Wednesday slammed Kiefer's behaviour, labelling it disgraceful.

"You've got no respect for anyone's property or the law," he said.

"The community needs to be protected from people like you."

Police documents outlining Kiefer's crimes reveal officers considered the Thirroul teen a habitual offender who showed "no intention of stopping his criminal activity".

They also revealed residents in at least one Bulli street lived in constant fear of Kiefer and his "gang", who called themselves the Reckless Thoughts Crew (RTC), and feared reprisals if they reported matters to police.

The documents said Kiefer had been known to police through his links to the gang Show No Mercy (SNM or SNEM) before moving to Griffith at the beginning of 2013.

However, he returned six months later and was soon up to his old tricks, posting about his graffiti intentions on social media before carrying out the acts.

Between August 7 and August 15, police recorded Kiefer's tags - SKOPE, PLUS and RTC - scrawled across buildings, bridges, train carriages and brick walls at multiple locations around Bulli and Thirroul.

In November, he attacked a driver sitting at traffic lights in Thirroul before assaulting a witness to the incident. A month later, Kiefer threatened the same witness's older brother in the hope the other man would withdraw his police statement.

He was arrested after being caught vandalising Corrimal railway station and exposing himself to the CCTV camera.

Mr Stoddart ordered Kiefer to spend at least 12 months in jail, to begin from December last year, when he was first taken into custody.