How Australian traffic lights work

Australian traffic lights use a three-colour system (red, yellow/amber, green) with arrows and special signals, run by adaptive control systems like SCATS, and coordinated sensors to manage vehicles, pedestrians and public transport; you must stop on red, stop on yellow unless unsafe, and you cannot turn left on red unless a sign explicitly permits it. This article explains how the signals are designed, timed and operated nationwide, how pedestrians and cyclists are accommodated, and what the rules mean in everyday driving.

The basics: colours, arrows and what they mean

Across Australia, traffic signals follow nationally consistent rules and layouts so drivers see the same meanings wherever they travel. The standard vertical arrangement is red at the top, yellow (amber) in the middle and green at the bottom, with additional arrow aspects to control specific turning movements.

• Red: Stop and remain stopped behind the stop line until a green signal or a green arrow for your movement appears.
• Yellow (amber): Prepare to stop; you must stop unless it is unsafe to do so (for example, you are too close to the stop line to stop safely).
• Green: Proceed if the way is clear; you must still give way to pedestrians and to vehicles as required by the rules (e.g., when turning across oncoming traffic).
• Arrows: Green arrows give a protected turn (only your turn moves; conflicting traffic is held). Red arrows prohibit that specific turn even if the full green is on. Yellow arrows warn that the protected turn is ending.

These indications are uniform under the Australian Road Rules and related standards so drivers can quickly interpret movements, including turns that are separately controlled from through traffic.

Phasing and timing at intersections

Signal “phasing” is the order and duration of movements through an intersection. Engineers set these based on traffic volumes, speeds and safety needs, then adjust them dynamically using detection and central systems.

• Amber and clearance: Amber typically lasts about 3–5 seconds depending on approach speed, followed by a short all‑red “clearance” to let vehicles finish clearing the intersection.
• Cycle length: Total cycle times can range from about 60 seconds in low demand to 120–150 seconds in busy peaks; adaptive control can shorten or lengthen cycles in real time.
• Split and sequence: Time within a cycle is split among phases (e.g., through, right turn arrows, pedestrian phases), and the sequence can change to serve the highest demand safely.
• Coordination: On corridors, signals are coordinated so platoons of vehicles get successive greens (a “green wave”), improving flow and reducing stops.

These timings balance safety with efficiency; clearance intervals protect late crossers, while coordination improves corridor travel times and reliability.

Detection and control systems

Australian signals are mostly “actuated,” meaning they respond to actual demand sensed at the intersection, and many are linked to central adaptive systems that optimise timing continually.

• Vehicle detection: Inductive loops in the road, video analytics, radar or magnetometers detect waiting and approaching vehicles to call or extend green time.
• Pedestrian call buttons: Push‑buttons register a request to cross; the system grants a safe crossing phase in the next suitable part of the cycle.
• SCATS adaptive control: The Sydney Coordinated Adaptive Traffic System (SCATS), developed in NSW and used across Australia, adjusts cycle length, green splits and offsets in real time based on detector data.
• Priority and pre-emption: Many corridors provide transit signal priority for buses and trams and, in some jurisdictions, emergency vehicle priority, advancing or extending greens when safe.

By combining detection with adaptive control, intersections can serve varying demand throughout the day without manual retiming.

Pedestrian operation and accessibility

Pedestrian signals are designed to provide clearly understood crossing stages and accessibility features for people with vision or mobility impairment.

• Signals: A steady green walking figure (walk) invites pedestrians to start crossing; a flashing red figure signals the clearance period (finish crossing but do not start); a steady red figure means do not start.
• All‑walk phases: Some intersections use a Barnes Dance (all‑pedestrian) phase, stopping all vehicles so pedestrians can cross in any direction, including diagonally.
• Accessible pedestrian signals (APS): Push‑buttons include a locator tone, tactile arrow and vibro‑tactile feedback, with walk beeps that automatically adjust volume to ambient noise.
• Countdowns: Pedestrian countdown timers exist in some locations but are not a national standard; availability varies by state and site.

Together, these features provide predictable crossing opportunities and support independent travel for people with disabilities while keeping traffic flowing.

How pedestrian timing is set

Engineers set a short “walk” invitation (often a few seconds) followed by a clearance time based on the crossing distance and a design walking speed (commonly around 1.2 m/s, with slower speeds used near hospitals, seniors’ areas or schools). If the clearance has begun, pedestrians already on the crossing have time to finish safely; new starters should wait for the next walk signal.

Bikes, trams and buses at signals

Separate signals and rules help manage non‑car modes that share or cross intersections, particularly in cities with extensive tram networks and growing bike infrastructure.

• Bicycle lanterns: Small bicycle symbols provide bike‑only movements, sometimes with an early start (leading bike interval) or protected turns.
• Tram signals: Dedicated white “T” aspects authorise tram movements independent of general traffic signals, improving tram priority and safety.
• Bus signals: In some jurisdictions, white “B” aspects or priority phases help buses depart stops and clear intersections faster.
• Hook turns: In parts of Melbourne and some other sites, right turns are made from the left lane when signed (“Hook Turn”) to keep trams moving; signals and signs guide the sequence.

These tools give public transport and cyclists safe, efficient passage without unduly delaying other traffic.

Turning rules at signalised intersections

Turning movements are tightly defined to reduce conflicts and confusion. Signs and arrows at each intersection specify what is allowed.

1. Left turns: You may turn left on a green circle when permitted and safe; a red left arrow prohibits the turn. Turning left on red after stopping is generally illegal unless a sign explicitly allows it at that intersection.
2. Right turns: On a green arrow, the turn is protected. On a green circle without a right‑arrow, you may turn right if there is a safe gap and you give way to oncoming traffic and pedestrians.
3. Slip lanes: Left‑turn slip lanes are often controlled by give‑way signs rather than signals; drivers must give way to pedestrians in the marked crossing and to other traffic as signed.
4. U‑turns: At signalised intersections, U‑turns are generally prohibited unless a “U‑turn permitted” sign is present (Victoria is a notable exception where U‑turns are allowed at signals unless prohibited by signage).

Always obey arrows and signs at your specific approach; they override general rules for that movement at that location.

Safety, outages and enforcement

Signals incorporate safeguards and are backed by enforcement to deter risky behaviour, with clear rules for unusual conditions like blackouts.

• Red‑light and speed cameras: Many intersections use combined cameras to enforce stop‑line compliance and detect vehicles speeding through on red.
• Blackouts or dark signals: If the lights are not operating, treat the intersection as uncontrolled and follow give‑way rules (typically give way to the right and to pedestrians), unless police or temporary traffic control is present.
• No overnight flashing: Unlike some countries, Australian signals are rarely set to flashing yellow at night; actuated operation with shorter cycles is preferred for safety.
• Visibility and maintenance: Lanterns, backboards and LED optics are specified for high visibility, and faults are monitored and repaired by state or local road authorities.

These measures help keep intersections safe under normal operation and during disruptions, with clear legal expectations for drivers and pedestrians.

Standards and who’s in charge

Australian practice is anchored by the Australian Road Rules and technical standards. AS 1742 (Manual of Uniform Traffic Control Devices, Part 14: Traffic signals) and AS 2144 (traffic signal lanterns) set layouts and performance. Austroads publishes national guidance for design and timing. State and territory road agencies (such as Transport for NSW, the Queensland Department of Transport and Main Roads, Main Roads WA, the Victorian Department of Transport and Planning, and others) design, operate and maintain the networks, most of which run on SCATS.

Common misconceptions

Some persistent myths can lead to unsafe or illegal behaviour. Here are clarifications to keep in mind.

• “Left on red is allowed if you stop first.” No—only where a specific sign says it’s permitted.
• “Amber means speed up.” No—amber means stop unless stopping is unsafe.
• “Pressing the pedestrian button repeatedly makes it go faster.” No—one press is enough; the system will serve the crossing when safe and efficient.
• “Signals switch to flashing at night.” Rare in Australia; most intersections stay fully operational and adaptive overnight.
• “Countdown timers are everywhere.” Not nationally; some trials or locations exist, but they’re not a universal feature.

Knowing the facts helps everyone share intersections more safely and predictably.

Summary

Australian traffic lights use a standard three‑colour system, arrows and special tram/bus/bike signals, coordinated by sensors and adaptive control (notably SCATS). Pedestrian stages include a green walk and a flashing red clearance, with accessible push‑buttons and, in some places, all‑walk phases. Turning rules are defined by arrows and signs—left on red is only allowed if signed—and timings balance safety with flow through amber and all‑red clearances and corridor coordination. Uniform standards and strong enforcement underpin consistent, safe operation across the country.

How do traffic lights know when to change in Australia?

Detectors are wire loops located just under the road surface. You can see the outline of the rectangular loops at most intersections. The detector loops work by sensing the metal in vehicles.

Can I turn left on a red light in Australia?

No, you cannot generally turn left on a red light in Australia; it is only permitted where a specific road sign, stating “Left turn on red permitted after stopping,” is present at the intersection. At these designated intersections, you must come to a complete stop, then turn left only when it is safe and you have given way to all other vehicles and pedestrians. 
Key Requirements

• Signage is Essential: You can only turn left on a red light if there is a sign explicitly permitting it. 
• Stop First: You must come to a complete stop at the stop line before turning. 
• Give Way: You must give way to any vehicles approaching from the right or turning right, as well as to pedestrians crossing the road. 
• Safety First: Only proceed with the turn if it is safe to do so. 

Important Considerations 

• No Universal Rule: This rule is not standard across Australia. Drivers must look for the sign at each intersection.
• Penalties for Non-Compliance: Failing to stop or give way on a left turn on a red light can result in a fine and demerit points.

What is the sequence of traffic lights in Australia?

Traffic lights have the phasing red, green, yellow, red, and this applies whether they are at an intersection or a pedestrian crossing. There is no red plus yellow, and red always means stop (there’s no automatic free turn like there is in America).

Are traffic lights on timers or sensors in Australia?

They’re actually sensors to monitor traffic flow 🚦 If the sensors notice more traffic on one side of the intersection than the other, they communicate with the lights to adjust their configuration to suit 🛣 That’s why if you pull up to a red light late at night, you’ll see it turns green almost immediately 🤷‍♀️