Traffic Signs: The Visual Database of Control

2. Traffic Signs: The Visual Database of Control

Traffic signs in Singapore adhere to international conventions, primarily derived from the Vienna Convention on Road Signs and Signals, but with specific local adaptations. For the purpose of the BTT, signs are categorized by function: Mandatory, Prohibitory, Warning, Regulatory, and Information. A nuanced understanding of these categories is critical, as the test frequently presents similar-looking signs to test the candidate’s precision in identification.8

2.1 Mandatory Signs: The Imperatives of the Road

Mandatory signs communicate instructions that must be obeyed. Non-compliance is a traffic offense. These signs are typically circular with a blue background and white symbols, a color scheme chosen to signify positive instruction.9

2.1.1 Analysis of Directional Mandates

The “Turn Left/Right Only” Sign

Visual Descriptor: A blue circle containing a white arrow turning 90 degrees to the left or right.
Regulatory Implication: This is an absolute command. It is not a suggestion or a navigational aid; it indicates that the only legal maneuver at the junction is to turn in the indicated direction. This differs from a rectangular “One Way” sign, which describes the nature of the road.
Assessment Scenario: Question: “You approach a junction with a blue circular sign displaying a white arrow pointing left. What must you do?” Answer: “You must turn left.” Distractors often include “Turn left if you wish” or “One way street to the left”.10

The “Keep Left/Right” Sign

Visual Descriptor: A blue circle with a white arrow pointing diagonally downwards to the left or right.
Regulatory Implication: This sign is crucial at traffic islands, dividers, and road bifurcations. It mandates the side of the obstruction on which the driver must pass. “Keep Left” is the standard default in Singapore’s left-hand traffic system.
Safety Rationale: Failure to obey this sign often results in the vehicle entering the wrong side of the road, leading to head-on collisions.
Assessment Scenario: Question: “On a dual carriageway, you see a sign with a white arrow pointing diagonally down to the left. What does it indicate?” Answer: “Keep to the left side of the road divider”.8

The “Ahead Only” Sign

Visual Descriptor: A blue circle with a white arrow pointing vertically upwards.
Regulatory Implication: Vehicles must proceed straight. Turning left or right is prohibited. This sign essentially functions as a combined “No Left Turn” and “No Right Turn” prohibitory sign but uses positive reinforcement.
Assessment Scenario: Question: “Can you make a turn at a junction displaying this sign?” Answer: “No, you must proceed straight ahead”.8

2.1.2 Priority Mandates: Stop and Give Way

The STOP sign and the GIVE WAY sign are unique in the mandatory category as they possess distinct shapes to ensuring recognition even if the face of the sign is obscured or viewed from behind.8

Sign Name	Shape & Color	Regulatory Requirement	BTT Assessment Logic
STOP	Red Octagon (8-sided) with white text.	The vehicle must come to a complete standstill behind the stop line, regardless of whether the road is clear. “Rolling stops” are illegal.	Q: “The road is clear at a Stop sign. What must you do?” A: “Stop at the stop line and proceed only when safe.” 12
GIVE WAY	Inverted Red Triangle with white background.	The vehicle must yield to traffic on the major road. Stopping is required only if necessary to avoid collision.	Q: “Approaching a Give Way sign, what action should you take?” A: “Slow down, and stop if necessary to let other traffic pass.” 8

2.2 Prohibitory Signs: The Constraints of Law

Prohibitory signs forbid specific actions. They are visually distinct, featuring a white circular background with a red border. Most include a red diagonal bar across a black symbol to indicate the negative command.13

2.2.1 Access Restrictions

The “No Entry” Sign

Visual Descriptor: A red circle with a horizontal white bar.
Regulatory Implication: Entry is prohibited for all vehicular traffic. This is absolute and applies to bicycles, motorcycles, and automobiles. It typically marks the exit of a one-way street.
Assessment Scenario: Question: “You see a red circle with a white horizontal bar. What does it mean?” Answer: “No entry for all vehicles”.11

The “No Motorcycles” Sign

Visual Descriptor: A white circle with a red border and a silhouette of a motorcycle.
Regulatory Implication: Entry is prohibited for motorcycles. This is often found at the entrances to certain tunnels (e.g., parts of the KPE/MCE during pilot phases or specific maintenance lanes) or pedestrianized zones.
Assessment Scenario: Question: “Who is prohibited from entering a road with this sign?” Answer: “Motorcyclists”.12

2.2.2 Maneuver Restrictions

The “No U-Turn” Sign

Visual Descriptor: A white circle, red border, and an inverted ‘U’ arrow crossed out with a red diagonal line.
Regulatory Implication: U-turns are strictly forbidden. In Singapore, the general rule of thumb is that U-turns are prohibited unless a sign explicitly permits them; however, this sign is placed at junctions to reinforce the prohibition where drivers might erroneously attempt the maneuver.
Assessment Scenario: Question: “Are you allowed to make a U-turn at a junction displaying this sign?” Answer: “No.”.2

The “No Overtaking” Sign

Visual Descriptor: A white circle, red border, showing two cars (one red, one black) side by side.
Regulatory Implication: Overtaking is prohibited. This is typically placed on narrow roads, bends, or areas with limited visibility. It acts in concert with double white lines.
Assessment Scenario: Question: “What does this sign indicate regarding passing other vehicles?” Answer: “Do not overtake.”.11

2.2.3 Parking and Stopping Restrictions

The distinction between “No Parking” and “No Stopping” is a frequent source of error in the BTT.

Sign Name	Visual Descriptor	Restriction Detail	Permitted Actions
No Parking	Blue circle, red border, single red diagonal line.	Parking (leaving the vehicle stationary) is prohibited.	Immediate pick-up and drop-off of passengers is allowed. 9
No Stopping	Blue circle, red border, red ‘X’ (cross).	Stopping the vehicle for any reason is prohibited (except emergencies).	None. Even immediate boarding is illegal. 9

2.3 Warning Signs: Anticipating Hazards

Warning signs are triangular with a red border and white background. They do not issue commands but alert drivers to hazards that require a reduction in speed and increased vigilance.12

2.3.1 Road Geometry Warnings

Road Narrows

Visual Descriptor: A triangle depicting two vertical black lines that converge.
Safety Implication: The road width is reducing. This eliminates the safety margin for passing.
Assessment Scenario: Question: “What should you do when you see the ‘Road Narrows’ sign?” Answer: “Slow down, do not overtake, and do not park.”.14

Dual Carriageway Ends

Visual Descriptor: A triangle showing two distinct roadways merging into a single two-way road.
Safety Implication: The physical barrier separating opposing traffic is ending. Drivers will soon be sharing the road with oncoming vehicles, significantly increasing the risk of head-on collisions if lane discipline is poor.
Assessment Scenario: Question: “What hazard does this sign indicate?” Answer: “Two-way traffic ahead; the dual carriageway is ending.”.8

2.3.2 Environmental Warnings

Slippery Road

Visual Descriptor: A car silhouette with skid marks behind it.
Safety Implication: The road surface has reduced friction, possibly due to materials used or frequent oil deposits.
Assessment Scenario: Question: “What driving technique should be used after passing a ‘Slippery Road’ sign?” Answer: “Slow down and avoid sudden braking or acceleration to prevent skidding.”.8

Low Flying Aircraft

Visual Descriptor: A silhouette of an airplane.
Safety Implication: Found near airports (Changi, Seletar, Paya Lebar). It warns of sudden noise that might startle drivers.
Assessment Scenario: Question: “What is the danger associated with this sign?” Answer: “Sudden noise from low-flying aircraft.”.12

2.4 Information Signs: Navigational Aids

Information signs are typically rectangular. Their background color denotes the road type:

Blue: Major roads and routes.
Green: Expressways (e.g., PIE, ECP).
Brown: Places of interest/recreation.
White: Local destinations.11

The “One Way” Sign

Visual Descriptor: A blue rectangular sign with a large white arrow.
Regulatory Implication: Confirms the road is one-way. This is distinct from the mandatory “Ahead Only” sign.
Assessment Scenario: Question: “What does a rectangular blue sign with a white arrow indicate?” Answer: “Traffic travels in one direction only.”.9