why are some street lights blue or purple

Nations worldwide in cities and along roads and highways have begun noticing something oddly different that is, street lights not glowing white or yellow but a purple hue. On the surface, the purple color can be viewed as either futuristic or artistic. This color change is, however, hardly ever deliberate. And in most instances, it is indicative of some technical issue with the lighting technology.

We are going to discuss in this article why certain lights in the streets are purple, why they change color, and why it is important to the safety and management of infrastructure.

The LED Street Lighting emergence.

In the last ten years, several cities have substituted the conventional street lights with the LED street lights. LEDs have a number of benefits over the previous lighting technologies like the high-pressure sodium lamps:

• Lower energy consumption
• Longer lifespan
• Reduced maintenance costs
• Efficiency in lighting.

These advantages have enabled the use of LED lighting to become the standard light of the contemporary roadways, parking lots, and the open areas. But with the application of both LED technology at massive scale, some manufacturing flaws and material problems have become more evident.

Among the most notable of those problems is the problem of the purple street light.

Why do some of the Streetlights Go Purple?

Street lights are mostly purple due to the degradation of the phosphor layer in LED bulbs.

It is best to know how the white LED lighting works in order to comprehend this problem.

The manufacture of White LED Lights.

White LEDs do not produce white light as compared to traditional bulbs. Rather, they are based on a mixture of elements:

1.Blue LED chip – gives out blue light.

2.Phosphor coating – transforms some of the blue light into others.

3.Mixed spectrum – the light that is present is white to the human eye.

Under normal conditions, the blue light is adjusted to produce a balanced white color by phosphor layer.

What Will be the Result of the Phosphor Layer Failure.

When the phosphor screen starts to wear out, crack, or become detached off the LED chip, then the conversion process no longer functions correctly. Consequently, an increased amount of the blue or violet light gets out of the diode.

This change makes the light in the street look purple, blue or violet instead of white.

That is, when the street light is purple, it is a common case when the LED part is malfunctioning.

Ordinary Reasons of Purple Street Lights.

Phosphor degradation in LED streetlights can be caused by a few factors.

1.Manufacturing Defects

There were batches of LED fixtures made using lower quality phosphor or low quality adhesion between layers. Such elements disintegrate and result in obvious color changes over time.

That is why in some cases there is purple light on the whole neighborhood or highway.

2.Heat and Environmental Stress.

Lighting systems used outdoors are used in very rugged conditions. Extreme temperatures, moisture and UV exposures are known to cause the phosphor layer to break down faster.

The coating can also crack or delaminate off the LED chip after years of operation as a result of heat buildup and weather exposure.

3.Material Aging

Although there is good quality of manufacture, there is degradation of LED components with time. With aging, the optical property of materials varies resulting in changes in color temperature.

The old LED fixtures will thus tend to get a purple hue towards the end of their life.

Are the Street Lights in Purple Streets Hazardous?

Although the purple street lamps can be aesthetically appealing, they can pose a number of safety and visibility issues.

Reduced Visibility

White light gives a balanced light which assists the driver and pedestrians to distinguish objects, road signs and hazards. Street lights become purple in color, which makes the color distribution strongly biased in the blue wavelength.

This minimizes the general visual acuity and may increase the difficulty of discerning colors and other details in the dark.

Lower Color Rendering

The CRI is used to measure the quality of lighting. In case of the phosphor layer failure, CRI becomes very small.

It implies that objects, vehicles, and people can be distorted or more difficult to recognize when using purple lighting.

Glare and Eye Strain

The drivers may experience discomfort and glare due to blue-heavy light. The glare can be too much and this could decrease the reaction time and chance of young person being involved in accidents due to the glare.

This is why, most lighting engineers insist on the replacement of defective fixtures in the shortest time possible.

Reasons the Issue Baccalaureate Went Viral.

The phenomenon of the purple street lights appeared to increase its visibility over the recent years due to the rapid adoption of LED lighting across the whole world.

In the initial adoption stage, there were manufacturers who made high numbers of LED fixtures using phosphor materials which degenerated earlier than anticipated.

Due to the large number of lights (thousands) installed in many cities using the same production batches, failures could be observed across whole areas at the same time.

Though the affected fixtures are a rather small proportion of the total number of LEDs placed in the world, the strange purple glow renders the issue very noticeable.

The way Cities and Utilities are Correcting the Issue.

Purple street lights are normally treated by municipalities and lighting providers by offering programs of replacement of the fixtures.

Common solutions include:

• The replacement of faulty LED modules.
• Replacement with superior fixtures.
• Enhancing manufacturing quality.
• Installation of more stringent control of quality.

The advanced phosphor materials and the better packaging design to avoid premature degradation are employed by many manufacturers.

Is Prevention of Purple Street Lights Possible?

Yes, the issue can be prevented to a large extent by the use of improved engineering and maintenance methods.

Install LED Superior emitters.

The high-quality LED lighting systems have been developed in such a way that they contain longer-lasting phosphor and enhanced bonding layers to stand the test of time.

Periodic Inspection and Maintenance.

Regular checks will be used to detect the occurrence of color shifting before it spreads.

Select Quality Suppliers.

Products of lighting of renowned manufacturers are usually subjected to a lot of testing in terms of heat resistance, color stability and durability.

The Future of LED Street Lighting.

LED technology is the most efficient and sustainable form of lighting that is present even with the occasional purple street light.

Modern LED systems provide:

• Up to 70% energy savings
• Lifespans exceeding 50,000 hours
• Reduced light pollution
• The ability to be compatible with smart city infrastructure.

With the ever-improving materials and manufacturing processes, the problems with phosphor degradation are becoming more rare.

Final Thoughts

Purple street lights might seem strange, but it is normal to be a result of the LED components failure instead of design. The change of color is as the phosphor coating within the LED breaks down, and the blue or violet light prevails.

As striking as the phenomenon itself is, it may lower the quality of lighting and cause safety issues to drivers and pedestrians.

Luckily, with the replacement of older fixtures by cities and the advances in the manifestation of LEDs, the use of purple street lights will become even rarer in the future.