Modern traffic lights are the core infrastructure for regulating traffic flow, alleviating congestion, and preventing accidents. Whether on urban main roads or highways, they are essential for maintaining traffic order and ensuring the safe passage of vehicles and pedestrians.
Compared to traditional fixed-timing signals, modern traffic signals incorporate intelligent control, energy-saving technology, and adaptive adjustment functions. For example, while traditional signals can only switch colours according to pre-set timings, modern models can adjust signal durations based on real-time traffic flow, significantly enhancing通行 efficiency.
To explain the operational mechanisms of modern traffic signal lights in plain language, helping road managers, procurement parties, and interested users understand their technical highlights and practical value, providing reference for traffic facility upgrades or procurement.
LED Lighting: Modern traffic lights predominantly utilise LED lights, which offer three key advantages over traditional incandescent bulbs: first, energy efficiency (reducing energy consumption by over 80%); second, longevity (lasting over 50,000 hours, reducing replacement frequency); and third, high brightness (remaining clearly visible even in rain or fog), coupled with rapid response times that shorten drivers' reaction times.
Colour Configuration: The basic configuration includes red, yellow, and green universal signals. Additionally, there are specialised guidance lights, such as left/right turn arrow lights (indicating lane direction) and flashing lights (used for warning scenarios, such as malfunctions or temporary controls).
Hardware Core: Centred around a microcontroller or programmable logic controller (PLC), it is responsible for receiving data, performing calculations and analyses, and sending signal switching instructions to the lighting modules.
Software Support: Equipped with professional traffic signal control systems (such as SCATS or SCOOT systems), it incorporates timing algorithms or adaptive logic, which are key to achieving intelligent regulation.
Common detector types: Includes radar sensors (detecting vehicle speed and quantity), video cameras (using AI to analyse traffic density), and loop detectors (buried under the road surface to detect the passage of metal vehicles).
Core functions: Real-time collection of traffic data, such as lane queue length, pedestrian count, and vehicle travel speed, and feeding this data back to the control unit to provide the basis for signal adjustment.
Weather-resistant housing: Made from UV-resistant and impact-resistant materials (such as polycarbonate), it withstands external influences like heavy rain, high temperatures, and vehicle scrapes, ensuring stable operation of internal components.
Auxiliary components: Some traffic lights are equipped with reflective panels (to enhance visibility in low-light environments) and solar panels (to power traffic lights in areas without grid power, achieving green energy efficiency).
(1) Fixed Timing Control: Suitable for stable traffic flow scenarios
Operating Mode: Based on historical traffic data, pre-set signal cycles are established, such as a total duration of 90 seconds, with 40 seconds for red light, 40 seconds for green light, and 10 seconds for yellow light, cycling through the sequence.
Applicable Scenarios: Areas with minimal traffic fluctuations, such as suburban roads or roads surrounding residential communities, where frequent adjustments to signal durations are unnecessary.
(2) Adaptive Control: The ‘Smart Feature’ of Modern Traffic Lights
Data Collection: Detectors (radar/cameras) continuously capture traffic flow information in real-time, such as 20 vehicles queuing on the northbound lane and only 5 vehicles on the southbound lane. This data is transmitted in real-time to the control unit.
Algorithm Processing: The control system analyses the data using built-in algorithms to determine current traffic demand — extending the green light for the northbound lane when there are more vehicles and shortening the red light for the southbound lane when there are fewer vehicles.
Real-Time Adjustments: Duration is updated every 1–2 signal cycles, for example, extending the northbound green light by 15 seconds while shortening the southbound red light by 15 seconds, dynamically adapting to traffic changes (e.g., differences between peak and off-peak hours).
Red light: When the control unit sends a ‘stop’ command, the red LED lights up, prompting vehicles and pedestrians to wait. In some low-traffic areas, traffic lights use a flashing red light mode, equivalent to a ‘stop and observe before proceeding’ warning signal.
Yellow light: As a transitional signal between red and green, it typically lasts 3–5 seconds. When the control unit calculates that the current signal phase is about to end, it triggers the yellow light to remind drivers to slow down and stop, rather than accelerate to rush through.
Green light: The control unit activates the green light when it confirms that there is no conflicting traffic flow in the current direction (e.g., the opposing red light is already on). Arrow green lights are specific to certain lanes; for example, when the left-turn arrow green light is on, only left-turning vehicles are permitted to proceed, preventing lane conflicts.
Interconnected Intersections: Modern traffic lights are connected via 5G/4G networks to form a ‘signal network.’ For example, multiple traffic lights on a major road are synchronised by a control centre to create a ‘green wave band’—when drivers maintain a constant speed, they encounter consecutive green lights, reducing stops and waiting times.
Pedestrian signal coordination: When pedestrians press the request button near the crosswalk, the detection system transmits the ‘pedestrians waiting’ information to the control unit. The system prioritises shortening the vehicle green light duration and triggers the pedestrian green light in advance to ensure safe crossing.
Emergency Vehicle Priority: Linked with the emergency dispatch system, when an ambulance or fire truck approaches, the control unit quickly switches the signals—the direction of the emergency vehicle becomes green, while the opposite and side directions become red, creating a ‘green channel’ for the emergency vehicle.
LED lighting consumes 50%-80% less energy than incandescent bulbs and has a lifespan of over 50,000 hours, reducing labour and material costs associated with bulb replacements; weather-resistant housings also lower maintenance frequency, making long-term use more economical.
By adjusting signal durations based on real-time traffic data, red light times on congested lanes can be shortened during peak hours. For example, during the morning rush hour when there is heavy traffic heading into the city, the system automatically extends the green light duration for that direction, reducing waiting time by 20%-30% compared to fixed timing.
High-brightness LED lights combined with anti-glare design ensure clear signal transmission even in low-visibility conditions such as heavy rain, fog, or at night; Some signal lights are also equipped with countdown displays, allowing drivers and pedestrians to anticipate signal changes in advance, thereby reducing sudden braking or reckless driving.
The control unit can upload operational data (such as bulb failures, power outages, or detector abnormalities) in real-time to the management centre. Staff can diagnose issues remotely without visiting the site and even remotely repair some software faults, significantly reducing fault resolution time.
A combination of ‘adaptive control + arrow lights’ is used. During morning rush hour, priority is given to extending the green light duration for inbound lanes, while during evening rush hour, the focus shifts to outbound lanes. Simultaneously, inter-intersection coordination creates green wave zones to enhance arterial road traffic efficiency.
Integrated with pedestrian detectors, the system automatically extends pedestrian green light durations during school commuting hours (e.g., from 20 seconds to 30 seconds) and activates flashing yellow lights to prompt vehicles to slow down. At night, the system switches to low-power mode to avoid bright lights disturbing residents' rest.
Use ‘traffic control signals,’ such as a 5-second green light and 10-second red light cycle, to prevent vehicles from queuing too long on ramps and blocking mainline traffic; traffic lights near toll stations adjust green light duration based on queue length to reduce congestion.
Signal lights equipped with solar panels charge batteries during the day via solar panels and switch to low-power mode at night (e.g., flashing red/yellow lights), meeting basic traffic control needs without requiring grid installation, thereby reducing construction costs.
Regularly clean the surface of LED lights to prevent dust or grease from obstructing light and affecting visibility;
Inspect detector status: clean camera lenses and repair damaged loop detectors beneath the road surface;
Test backup batteries (for power outages) to ensure the traffic lights can operate for 1–2 hours after a power failure.
Analyse historical traffic data (e.g., peak hours, accident-prone areas) to adjust control logic, such as extending yellow light duration at accident-prone intersections;
Regularly update control software to support new features (e.g., AI pedestrian detection, emergency vehicle coordination upgrades) to maintain the ‘intelligence’ of traffic lights.
Reduce traffic congestion and lower daily maintenance costs for labour and materials; remote monitoring functions simplify management processes and improve the efficiency of traffic facility control.
Reduce waiting times; arrow lights and countdown timers provide clear guidance, reducing violations or accidents caused by unclear signals, and enhancing the driving experience.
Pedestrian request buttons and coordinated signals ensure safe crossing; high-visibility signal lights allow cyclists to clearly determine the appropriate time to cross even in complex traffic flows.
Modern traffic lights operate through a closed-loop logic of ‘detection → control → signal output,’ leveraging LED lighting, adaptive algorithms, and synchronised systems to achieve more efficient, safer, and more energy-efficient traffic management than traditional signals.
If you have needs for road infrastructure upgrades or bulk purchases of traffic signal lights, we recommend choosing modern models with intelligent control and durability. We can provide customised solutions, offering full support from product selection to installation and commissioning. Please feel free to contact us for consultation to jointly enhance traffic efficiency and safety standards.
