The teenager was killed after his black Harley Davidson was involved in a collision with a grey Land Rover Freelander outside the former hospital on Thursday afternoon. A Liberty Bus was stationary at a stop nearby.
One of the messages left read: ‘We all miss you man. Come back to and make us laugh again.’
Another said: ‘Please tell us this isn’t true.’
Police said no arrests had been made and the incident was not being treated as a crime. The bus driver and other witnesses were interviewed at the scene. A 45-year-old woman who was driving the Land Rover was treated at the scene by paramedics but was not taken to hospital.
The road was closed for more than seven hours and re-opened just after midnight.
In a statement Liberty Bus said they had provided CCTV footage from their vehicle to the police.
Police are appealing for anyone with any information to contact them on 612612 or call Crimestoppers on 0800 555 111.