When driving through rainy and foggy sections at night, do the flashing solar road studs on the road surface quietly change the force with which you step on the accelerator? This seemingly minor traffic facility actually affects the core of traffic safety and engineering decisions - will solar road studs increase or decrease vehicle speeds, or will they have no impact at all?
The answer to this question is directly related to the layout choices of road designers, the safety control of managers, and the driving experience of every driver. According to relevant research, the guiding role of road signs on driving behavior may be magnified by 1 to 2 times in complex road conditions. Next, NOKIN will provide you with a detailed analysis of the impact of solar road studs on vehicle speed, offer design suggestions for different scenarios, and ultimately reveal the truth behind the connection between "road studs and vehicle speed" for you.
To determine whether solar road studs affect vehicle speed, it is first necessary to clarify their core function - as an "enhanced version" of road markings, their essence is to convey road information through light signals rather than directly interfere with vehicle speed.
Road studs are mainly divided into two types, and their light-emitting principles and application scenarios are significantly different:
They have no built-in power supply and emit light by reflecting vehicle lights. They are commonly found on urban roads with abundant street lamps.
Equipped with built-in LED lights and solar panels, they can emit light independently without external light sources and are suitable for rural areas, mountainous regions or tunnel sections without street lamps.
The core value of solar road studs lies in enhancing "visual recognition". The specific functions and performance parameters are shown in the following table:
|
Function Type |
Application Scenario |
Nighttime Visible Distance (Manufacturer Data) |
|
Lane marking |
Urban main roads and expressways |
Passive type: approx. 50–80 m; Active type: approx. 200–300 m |
|
Curve guidance |
Mountainous curves and continuous curved sections (flashing mode) |
Up to 350 m |
|
Construction warning |
Road maintenance and temporary control areas with high-contrast colors (red/yellow) |
Approx. 250 m (active type) |
|
Edge indication |
Rural roads and bridges without guardrails (white active type) |
Approx. 220 m |
Regarding the correlation between solar road studs and vehicle speed, multiple studies have provided clear data support. The core conclusions can be summarized into three points:
A 2023 study revealed that among nearly 10,000 vehicle speed samples collected, the variation in average road speed after installing solar road studs was all within ±3km/h, failing to reach a statistically significant difference.
The research also points out that the key factors truly influencing vehicle speed are the road conditions themselves, such as the design of the confluence area, the curvature of the curve, the slope, and whether there is street lighting. The influence weight of these factors is 3 to 5 times that of road studs.
The results of a driving simulation experiment show that on complex sections such as curves and downhill sections, active luminous road studs can enable drivers to perceive road changes earlier.
The driver's reaction time for identifying curves is shortened by 0.8 to 1.2 seconds.
The average deceleration distance before entering a curve increases by 15 to 20 meters, effectively reducing the risk of cornering.
After installing flashing solar road studs on sections without street lamps at night, drivers' "driving confidence score" increased by 40%, but the cruising speed did not rise significantly.
This is because the "clear boundary" provided by road studs mainly reduces drivers' hesitation due to unclear road conditions rather than encouraging acceleration.
Why can solar road studs guide deceleration in some scenarios but have no effect in others? Behind this lies the dual effect of visual perception and driving psychology.
solar road studs transform the "geometric shapes" of the road (such as the direction of curves and lane widths) into intuitive visual cues through continuous light signals. For instance, the road studs at the bends are arranged in a curve, allowing drivers to predict the road direction from 100 meters away and thus release the accelerator in advance to slow down.
This kind of "early perception" is not about forcing deceleration, but rather making driving operations more composed and reducing situations such as sudden braking or speeding through corners.
A study by an Italian university pointed out that dense solar road studs visually form "road boundaries", making drivers subconsciously feel that "the lane range is clearer", and thus voluntarily slow down to avoid crossing the line.
This effect is particularly evident in "space-constrained" scenarios such as narrow Bridges and construction sections, which can reduce vehicle speed by 5 to 8 kilometers per hour.
If the road studs are improperly designed, they may also indirectly affect the stability of vehicle speed. For instance, some low-quality active road studs have excessively high brightness, which can cause "glare" in rainy or foggy weather, making it difficult for drivers to see the road conditions clearly for a short time. This may lead to situations such as "sudden deceleration" or "unconscious acceleration to avoid".
However, this situation is a "design error" rather than an inherent influence of the road studs themselves. It can be effectively avoided by standardizing the light intensity parameters.
The impact of solar road studs on vehicle speed is highly dependent on the "usage scenario". Its effect varies significantly under different road conditions:
solar road studs only serve as auxiliary signs and have almost no impact on average vehicle speed. They can only enhance lane change safety during peak hours when changing lanes.
Active luminous road studs can increase the "road condition recognition distance" from 30 meters to over 200 meters, reducing the low-speed situation where drivers are reluctant to drive due to "unclear vision", making the vehicle speed more stable without causing speeding.
solar road spikes (especially in flashing mode or yellow/red) can enable drivers to perceive risks 0.5 to 1 second in advance, reducing the average speed of cornering by 6 to 10km/h and lowering the rate of scratches in merging areas by 30%.
High-contrast color (such as red) active road studs combined with flashing mode can enable drivers to perceive the construction area from 500 meters away, slow down in advance, and reduce the overspeed around the construction area by 45%.
To maximize the safety value of solar road studs while avoiding negative impacts on vehicle speed, the following design and layout principles should be followed:
Prioritize the use of white solar road studs in always-on mode to avoid excessive stimulation.
Yellow cat's eye road studs are used, with low-frequency flashing (3-5 times per second) to enhance warning.
Use red solar road studs that flash at medium frequency (5-8 times per second) to clearly signal the prohibition.
The spacing of solar road studs on different sections of the road varies greatly, as detailed in the following table:
|
Road Section Type |
Transverse Spacing (from Lane Edge to Road Studs) |
Longitudinal Spacing (between Adjacent Road Studs) |
|
Urban main straight roads |
20–30 cm |
5–8 m |
|
Mountain curves |
15–20 cm (denser on the inner side of the curve) |
2–3 m |
|
Expressways |
25–30 cm |
10–15 m |
|
Temporary construction sections |
10–15 cm |
1–2 m (continuously laid) |
Road studs must be used in conjunction with road markings, street lamps, and traffic signs, and cannot replace direct speed control facilities such as speed limit signs and speed bumps.
Select solar road studs that meet standards, with light intensity controlled between 200 and 500cd (to avoid glare), and a pressure resistance of ≥100kN (to withstand heavy vehicles).
Clean the surface of the cat's eye road studs every 3 to 6 months (to prevent dust from blocking), and inspect the solar panels and batteries every 1 to 2 years to ensure the lighting effect.
When applying solar road studs, three types of risks need to be guarded against to avoid adverse effects on vehicle speed control:
Some cat's eye road studs may cause "visual interference" to drivers at night due to excessive brightness or improper flashing frequency (such as more than 10 times per second), which may lead to temporary distraction and subsequently cause speed fluctuations. The solar road stud manufacturer suggests that you can control the light intensity of the road studs at 200-500 CD and the flashing frequency ≤8 times per second.
If cat's eye road studs are wrongly arranged in the "speed bump style" (such as continuously and densely arranged on a straight section of road), it will make drivers mistakenly believe that there is a speed bump ahead, leading to unnecessary sudden braking and increasing the risk of rear-end collisions instead. The layout of road studs must strictly match the function of the road to avoid transmitting incorrect information.
In winter, snow cover and in summer, high temperatures and intense sunlight may cause the cat's eye road studs to lose their luminous function or get damaged. In snowy areas, it is recommended to choose road studs with a protrusion height of ≥15mm to reduce the risk of being buried by accumulated snow. In high-temperature areas, ABS material that can withstand temperatures above 120℃ should be given priority.
In most scenarios, solar road studs do not cause a significant increase in average vehicle speed. Their essence is an "information transmission tool" rather than a "speed control facility". On risky sections such as curves, downhill sections, and construction sites, the actively illuminated road studs can provide visual prompts to prompt drivers to slow down in advance and operate with caution, effectively reducing the risk of accidents caused by speeding. The impact of road studs on vehicle speed ultimately depends on "design rationality and scene matching degree". Road studs that are properly laid out and regularly maintained can enhance road safety without interfering with normal vehicle speed.
