A teenager spraying graffiti tags in Sydney's inner west was caught "off-guard" and killed instantly by a train he may not have heard coming, a coronial inquest has heard.

Apprentice plumber Tre Toman, 18, was tagging near Lewisham station with two friends on the night of January 11 last year when a city-bound train hit him at the West Street overpass.

A graffiti tag close to the tunnel at Lewisham appeared to show the word "Ontre". Credit:Nick Moir

The Glebe Coroners court on Wednesday heard that Mr Toman loved painting and spraying his "Ontre" tag, which can still be seen along rail corridors and elsewhere around Sydney.

Leading Senior Constable Sarah Jessup, who attended the scene on the night, said Mr Toman was killed instantly when the train cut him in two.