They’re purple, but not for TCU

Streetlight on McAlister Road in Fort Worth, March 18, 2024Photo bySouthside Matt

Since moving in 1910 to Fort Worth from Waco, Texas Christian University and the city have enjoyed a close relationship. It is this relationship that has made Fort Worth a favorite of ESPN’s College Gameday program during college football season. The university has made itself Fort Worth’s “hometown university” and has consistently drawn residents from the city to sporting events, even in years when the teams have not performed as well as hoped for.

To promote the university and its sports teams, the city has made available light poles for signs and has often publicized events through city proclamations and other official acts.

With the way that “Horned Frog Pride” flows through the city, one entering Fort Worth, including those who are returning to their home city with that pride in mind, would not be surprised to find purple street lights. This is what many are finding throughout the city, and many are associating this with the city’s relationship with the university.

TCU sports have brought moments and seasons of great anticipation. The football team has had some great seasons and even been national champions on two occasions. The baseball team has made its way to Omaha, Nebraska, for the College World Series tournament on six occasions. Their men’s and women’s basketball, volleyball, and equestrian teams have also all developed respectable programs in their respective sports.

The purple lights, though, are not to celebrate TCU, even with the appearance of the Horned Frogs in the 2022-23 College Football Playoff Championship Game. Instead, they are a side effect experienced by early adopters of LED street lights in an attempt to provide a clearer, white light.

Starting around 2008, various cities throughout the nation, and internationally, began moving from lights that used sodium for illumination and that produced a yellowish-orange light. The new lights selected were illuminated through light-emitting diodes (LEDs) that produced a whiter light and also were more economical. Fort Worth was one of these cities to adopt the new lights.

McAlister Road west of I-35W in Fort Worth, March 18, 2024Photo bySouthside Matt

Encouraged by the U.S. Department of Energy (DOE), lights that include LEDs add the qualities of being more durable and longer-lasting than other types of lighting. “LEDs are one of the most energy-efficient lighting technologies that currently exist” as reported by Scientific American.

White is actually a mixture of all colors together, despite what you might find using a bunch of crayons to develop white. This is why physics classes use a prism to split the white light into the array of colors, as so eloquently displayed through the cover for Pink Floyd’s album “Dark Side of the Moon.”

Cover image from Pink Floyd's album "Dark Side of the Moon"Photo byCapitol Records

To create the appearance of white light, some early methods used only blue LEDs but covered them with a fluorescent substance, phosphor. This is not dissimilar from LED vehicle headlights that provide a white light for the driver but appear blue or purple to oncoming traffic.

Over time, the phosphor begins to wear off. This reveals the blue light coming from the actual LED, but the effect caused by the remaining phosphor as well as the red and yellow light that is still emitted through the phosphor combines to create the purple hue. As the phosphor continues to wear, the effect is enhanced continuing the purple effect to become deeper.

The purplish hue caused by this effect, often considered to be within the spectrum of blue-tinged light, does provide better peripheral vision. On the flip side of this, though, is that an object seen in the peripheral vision actually can be lost in the background once it moves into focus. Particularly for drivers, this can create a road hazard.

Similarly, the blue- and violet-saturated light can make it difficult to distinguish between colors, causing everything to appear to be of a blueish or blackish shade. It is this effect that leads to objects seeming to blend together and become harder to see.

The loss of the phosphor also can dim the lighting. So, while the purplish hue can make things look more attractive, particularly to TCU fans, it also can make the area darker and more difficult to navigate visually.

Since 2021, this experience has been reported in several states including Florida, Utah, and Massachusetts as well as Texas. It has also been reported in other countries such as Ireland and Canada. Authorities in all of these areas have taken measures to replace these lights as they begin to turn to expose the purple color.

Logo for MyFW appPhoto byCity of Fort Worth

In Fort Worth, this is generally done through citizen reporting of lights that are experiencing this. Greatly expanded since being introduced, the MyFW app, available on both the Google Play Store and the Apple App Store, provides a quick and easy layout for citizens to use to submit such reports. The app also allows citizens to add pictures so that the city can view the affected area from the citizen’s standpoint and determine the severity of the issue immediately.

For those who do not wish to use the app, the city has also provided other methods for reporting concerns. Texting is available at 817-835-MYFW (6939). Citizens can also call the city customer service line at 817-392-1234. Email is another option, using the address 1234@FortWorthTexas.gov.