Translink staff and passengers were assaulted 115 times in the first eight months of 2018, the company has said.
Figures made available to BBC News NI recorded 69 physical attacks, including sexual assault.
There were also 46 incidents of people being verbally threatened or abused
The majority of incidents targeted Translink's bus and rail employees, with more than 72 incidents reported. The union Unite said assaults against workers were "rampant".
The man, who was on the service from Great Victoria Street in Belfast to Coleraine, allegedly attacked the employee at Antrim Station at about 11pm.
A train conductor's story
I was assaulted in 2016 and was left with bruised ribs and black eyes, and was off work for months after with stress.
It isn't nice when you have to sell a ticket to the person who left you in hospital.
It is hard when you know every time you pull up at a stop that the person who assaulted you is about to get on.
There are two members of staff on the new Gliders (Belfast buses) but on the train there is no protection.
We dread coming into the Christmas market time with huge crowds and people drinking.
They will all be put on a train with one person working on their own. We need more staff and more security on the train.
It wears you down where you don't want to go to work because you're afraid of what happens.
"These attacks can be quite serious and threaten lives," said Davy Thompson, Unite regional coordinating officer.
"Bus and rail drivers, inspectors and other public transport workers are entitled to go about their day's work in peace and to be shown basic respect.
"All too often the travelling public end up paying the price for these assaults - in recent months a number of public transport services have had to be withdrawn after repeated attacks on drivers.
"Translink management must ensure the safety of their staff and whilst we acknowledge that the company has improved the level of support offered to affected workers, unfortunately in way too many cases staff end up out of pocket due to the long-term impact of such assaults on their health".
There has been an upward trend in the total number of reported attacks against Translink's staff and passengers since 2014.
Almost 700 incidents have been recorded in the past five years.
A Translink spokesperson said: "The safety of our customers, staff and the wider public is our top priority.
"With about 3,800 employees and 14,000 services operating daily, we delivered over 81 million passenger journeys last year and have a very strong safety track record.
"We have a range of measures in place to enhance safety and deter anti-social behaviour such as staff training, working closely with the PSNI, security personnel in main stations, body cameras and CCTV."
Body cameras for staff were introduced at the beginning of 2017 in an attempt to deter people from engaging in anti-social behaviour but also to act as an evidence-gathering mechanism in the event of such behaviour.
The PSNI have also issued an appeal for people to act responsibly when using public transport.
Ch Supt David Moore said: "We work closely with our colleagues in Translink to help promote safety in the workplace and educate passengers to stay safe when travelling.
"Officers provide visibility across all bus and train stations to help deter criminal activity.
"Regular meetings take place with Translink employees to discuss both staff and passenger safety, the importance of recording and reporting incidents and keeping security measures updated.
"Passengers should feel safe when travelling on both buses and trains, but there is an onus to behave responsibly and respect those using public transport.
"If police are made aware of an offence committed on either bus or train, officers will investigate robustly and bring those responsible before the courts.
"Everyone deserves to be safe in their place of work and we are asking for the continued support of the whole community in showing zero tolerance to abuse of Translink staff."