How Are Road Studs Powered?

Road stud manufacturers understand that night driving poses a significant challenge for many drivers, not due to driving skills but rather the safety issues arising from insufficient lighting at night. With the widespread installation of road studs on roads of all types and levels, night driving has become “traceable.” Drivers can follow the light emitted by the road studs to safely navigate the correct path and return home safely.

These unassuming road studs installed on roads go unnoticed during the day, but as night falls and light levels decrease, they begin to shine brightly. Through passive reflection or active illumination, they form prominent light strips, especially in adverse weather conditions, providing drivers with clear road guidance and hazard warnings. So, how exactly are road studs powered? What makes them glow? In this article, Nokin will analyze the different power supply methods for road studs with you.
 

The Principle of Passive Reflective Road Studs

As a traffic device that does not require electrical power, reflective road studs utilize passive reflective technology to reflect light, providing drivers with road contour markings. Unlike active-illuminated road studs, reflective road studs completely rely on external light sources (such as vehicle headlights) to trigger the reflective effect. They offer significant advantages such as zero energy consumption and low maintenance, are unaffected by rainy or cloudy weather, and maintain consistent reflective performance. They are an ideal low-cost safety solution for remote areas or road sections without grid coverage.

Glass Bead Reflective Principle

The optical reflective mechanism of glass beads

The core component of passive reflective road studs is high-refractive-index glass beads, whose reflective principle is based on the optical focusing effect:  

• When vehicle headlights illuminate the surface of the glass beads, the light first refracts through the outer layer of the glass beads  

• The refracted light is focused onto the reflective layer at the back of the glass beads  

• The reflective layer reflects the light back along the original light path, creating a bright reflective point in the driver's field of vision

Impact of key parameters on reflective performance

Two physical properties of glass beads directly determine reflective efficiency:

• Particle size control: Smaller particle sizes (typically 0.3–0.8 mm) enable more concentrated light focusing, enhancing visibility at long distances

• Distribution density: A high-density arrangement of 80–120 beads per square centimeter maximizes reflective output per unit area

Reflective Film Reflection Technology

Multi-angle reflection design using micro-prisms

Reflective road studs use a micro-prism array structure, whose reflective principle differs from glass beads:

• Incident light undergoes multiple refractions and reflections within the micro-prisms

• Even when light enters at a large angle of 60°, it can still be reflected back toward the light source via the prism structure

• The patented prism angle design (typically 35°–42°) ensures stable reflectivity under all weather conditions

Engineering optimization of housing materials

The choice of housing materials directly impacts service life:

• Engineering plastic housing: Made from ABS or PC materials, featuring lightweight design (single unit weight ≤150g), UV resistance (weather resistance rating ≥5), and chemical corrosion resistance

• Metal alloy housing: Made from aluminum alloy or stainless steel, with a compressive strength ≥160MPa, capable of withstanding repeated rolling by 30-ton heavy-duty trucks

Optical Angle Optimization

Scientific setting of the reflective surface angle

The reflective surface of reflective road studs typically forms a 30°-45° angle with the horizontal plane. This angle is validated through optical simulation:

• Ensures effective reflection for vehicles within a distance of 50-200 meters

• Avoids glare caused by direct sunlight on the driver, enhancing driving safety

Curved surface structure with reduced diffuse reflection design

The non-spherical curvature design of the reflective road stud surface (curvature radius 5-8 mm):

• Reduces diffuse light loss during reflection (reducing loss rates by over 40%)

• Concentrates the reflective light beam within a ±15° field of view, enhancing driver visual perception

Active Light-Emitting Road Studs

Solar-Powered Road Stud Power Supply System

As a representative of active luminous traffic facilities, solar-powered road studs achieve continuous nighttime illumination through an energy conversion chain of light energy - electrical energy - light energy. Unlike passive reflective road studs that rely on external light sources, they actively emit light through an internal power supply system, providing more stable road markings in low-visibility environments (such as nighttime, heavy rain, or fog), particularly suitable for high-safety-requirement scenarios like highways and mountain roads.

Solar energy capture

The photovoltaic panel assembly integrated at the top of the solar road stud is the core of energy collection, with the following technical characteristics:

• Material Selection: Mainstream options include monocrystalline silicon (conversion efficiency 18%-22%) or polycrystalline silicon (15%-18%) semiconductor materials. Some high-end products utilize thin-film solar technology (flexible substrates suitable for curved surfaces).

• Optical design: The surface is coated with an anti-reflective film (transmittance improved by over 95%) to reduce light reflection losses.

• Factors affecting efficiency: Light intensity, incident angle (ideal tilt angle is ±5° of local latitude), and temperature (each 1°C increase reduces conversion efficiency by approximately 0.4%).

Energy storage

Technical highlights of the built-in energy storage unit include:

• Battery type: Lithium-polymer battery (energy density 200–300 Wh/kg) or supercapacitor (cycle life ≥100,000 cycles)

• Management system: Integrated BMS battery management chip with overcharge/overdischarge protection, temperature compensation (operating range -20°C to 60°C), and balanced charging functionality

• Endurance: Standard configuration (5W solar panel + 10Ah battery) can maintain normal operation of the LED light for 4 hours per night even under continuous 3 days of cloudy/rainy weather

Smart control

The automatic operation system consists of three major modules:

• Light sensing: Uses a photoresistor or photodiode with adjustable threshold (typical value 50–100 lux), supporting manual/automatic mode switching

• LED driver: Constant current drive circuit (current fluctuation ≤±5%), ensuring stable brightness under different voltages

• Operating modes: Supports three modes: constant on, flashing (60-90 times per minute), and intelligent dimming (adjusting brightness based on radar-sensed traffic flow)

Additional Notes on Power Supply Methods

In addition to solar power, active-emitting road studs can be powered by other methods. In urban roads, some road studs are powered by the grid. This method requires pre-buried cables during road construction, though the initial construction cost is higher, it provides continuous and stable power to the road studs, suitable for high-grade roads with extremely high requirements for road stud operational stability.

In temporary construction sections, road studs powered by disposable lithium batteries are more common. These road studs are easy to install and do not require complex wiring, but batteries need to be replaced regularly, with the replacement cycle depending on battery capacity and road stud usage frequency.
 

Road Studs Performance Comparison of Different Power Supply Methods

Road Studs Application Scenario of Different Power Supply Methods

Highways

On highways, a combination of solar-powered road studs and reflective road studs can be used. On straight sections with high traffic volume and fast speeds, reflective road studs can meet basic road marking requirements at a lower cost. On curved sections, where vehicle direction changes, higher visibility of road studs is required. Deploying solar-powered illuminated road studs can provide clearer road guidance through active lighting, reducing the risk of traffic accidents.

Rural Roads

Rural roads have relatively complex lighting conditions, so when selecting solar road studs, it is necessary to consider the average annual sunshine hours in the local area. For regions with average annual sunshine hours below 1,200 hours, it is recommended to use dual-crystal silicon photovoltaic panels. Dual-crystal silicon photovoltaic panels have higher photovoltaic conversion efficiency, enabling them to collect more energy under limited lighting conditions and ensure sufficient power supply for the road studs at night.

Municipal Engineering

In temporary construction areas of municipal engineering projects, rechargeable road studs can be used. These road studs support rapid charging via vehicle power sources, enabling quick deployment and energy replenishment during construction. When construction areas change, rechargeable road studs are also easy to move and reinstall, meeting the flexibility requirements for road stud deployment in temporary construction.
 

Conclusion

Different road stud power supply methods have their own advantages and disadvantages, and the appropriate choice should be made based on specific application scenarios. If cost is the primary consideration, reflective road studs are a good option; for scenarios requiring long-term reliable operation, solar-powered road studs are more suitable; and on high-grade roads, grid-powered road studs provide the most stable performance.

With the development of smart transportation, road stud power supply systems are expected to integrate with technologies such as 5G and the Internet of Things (IoT) in the future. For example, through remote power monitoring and fault warning functions, real-time monitoring and management of road stud operational status can be achieved, enhancing the efficiency and intelligence of road safety management. Building a road safety system based on intelligent power supply systems will provide drivers with a safer and more convenient driving environment.