On three separate occasions, Muhammad Fuad Kamroden assaulted or used criminal force on other drivers after getting into a dispute with them.
In the most serious incident, he punched a lorry driver, leaving the victim with facial fractures that required surgery.
Fuad, 35, yesterday pleaded guilty to two counts of using criminal force, one count of voluntarily causing hurt and one count of voluntarily causing grievous hurt.
Two other charges involving harassment will be taken into consideration during sentencing at a later date.
On Aug 12, 2016, Fuad and the lorry driver, Mr Pek Lian Hui, were in a car park at the National University of Singapore at 8.20pm when Fuad sounded the horn because he felt Mr Pek was driving too slowly ahead of him.
A heated dispute ensued when Mr Pek, 52, a contractor, alighted from his lorry and approached Fuad. Fuad punched him several times in the face, head and stomach, and stopped the assault only after his mother and a passer-by intervened.
Deputy Public Prosecutor Bjorn Tan said the incident left Mr Pek bleeding heavily from his injuries. A medical report later showed he had suffered fractures on his face and multiple facial abrasions, as well as swelling and tenderness. He received surgery to fix the broken bones four days after the assault.
This charge of voluntarily causing grievous hurt carries a jail term of up to 10 years, as well as a fine or caning.
While Fuad was on bail, he got involved in a second road rage incident. On Dec 2, 2017, Fuad, who was working as a private hire driver, side-swiped a taxi which was driving towards a pick-up point in Clarke Quay, along River Valley Road.
When both drivers alighted from their vehicles, an argument broke out. Fuad pointed his middle finger at the taxi driver, Mr Mohamed Iqbal Mohamed Shariff, 46, and pushed his left cheek, causing him to lose his balance. Mr Iqbal suffered bruising on his face and was given three days of medical leave.
In the third road rage incident which occurred in February this year while he was still on bail, Fuad punched another taxi driver, Mr Tio Seng Sing, 71, in the face after cutting in front of his cab on a motorbike. The incident happened in Selegie Road.
In yet another incident in May last year, Fuad pushed a man's shoulder, face and left elbow after the man accidentally bumped into him while walking in the opposite direction at VivoCity.
DPP Tan urged the court to sentence Fuad to 18 months and 6 weeks' jail.
In his mitigation plea, Fuad's counsel said his client had been seeking help for anger management issues since last year but added that "these things take some time". Fuad is expected to be sentenced on Sept 4.