18/08/2025
Unwritten Rules, Road Markings, and the Realities of Heavy Vehicle Operation in Singapore
The safe operation of vehicles, particularly heavy ones such as prime movers, buses, and lorries, depends not only on codified regulations but also on many unwritten rules that experienced drivers instinctively follow. These rules, though absent from textbooks, are essential in real traffic.
With the introduction of foreign driving instructors for Class 4 and 5 licences, an important question arises: will they follow altered rulebooks written by scholars who may not grasp the realities of heavy vehicle driving on Singapore’s roads? Drivers of prime movers and buses often face conditions where textbook instructions collapse. To stay safe, they must adapt or bend rigid rules, such as keeping to the leftmost lane in a roundabout, stopping at a green light when visibility is poor, or using a straight lane to make a turn in tight spaces.
Many of these adaptive practices, the unwritten rules, have been ignored, erased, or never codified. Trainee drivers are often taught idealised three lane roundabout models that do not exist in Singapore. Once an entrance or exit reduces to two lanes, the rules collapse. Fast moving vehicles naturally overtake slower ones, creating conflicts unrecognised in manuals.
Examples like the Fountain of Wealth roundabout and Exit 10B of the Woodlands checkpoint show drivers crossing double white lines not to break rules but to maintain safety and efficiency. Humans adapt; robots following programmed obedience would stall or create hazards. This gap between theory and practice shows why lawmakers, policymakers, enforcement officers, and even judges often lack full understanding of ground realities.
Another concern is the erosion of critical road markings. White thermoplastic arrows, especially when extended to six metres, provide advance warnings of junctions and split-second decision support for larger vehicles. A lorry driver in a straight lane but needing to turn relies on the first long arrow to decide whether to stop or proceed safely.
Yet in recent years, many of these markings have been erased, replaced by eighteen metre Mandatory Give Way to Bus zones, often without reinstatement. This creates risks not only for human drivers but also for autonomous vehicles that rely on clear markings.
The seriousness of this has not been fully recognised. Lawmakers overlooked it. Enforcement officers are not aware. Even judges may not grasp its impact. In 2022, case 216102837711, a judge asked if speed limit signages were mandatory, and the Traffic Police officer replied no. By 2024, rules changed, making them mandatory. Such transitions show how unwritten practices and shifting standards create inconsistent enforcement and uneven justice.
Judges must not be allowed to suspend or revoke licences when laws or markings have changed without notice to drivers. They are not equipped to make decisions on road design or evolving regulations, especially when unwritten rules and marking practices are not codified or communicated.
Recommendation:
Unwritten rules must be retrieved, documented, and shared among lawmakers, law enforcers, policy writers, prosecutors, and judges. Critical markings such as extended arrows must be reinstated where appropriate, including in bus lanes. Responsibility should rest with the LTA Traffic Engineering Department, working with Traffic Police, autonomous vehicle testing units, and seasoned Class 4 and 5 instructors who understand real conditions.
Without reform, Singapore risks a transport system governed by incomplete rules, blind to practical realities, and unsafe for both human and autonomous drivers.